Công bố quốc tế trong lĩnh vực kiến trúc, xây dựng (Tuần 4 tháng 7-2021)
Trong số này chúng tôi xin giới thiệu tới quý độc giả những nội dung chính của các công bố quốc tế đăng tải trên ScienceDirect và Springer Nature do Cục Thông tin khoa học và công nghệ quốc gia (NASATI) mua quyền truy cập như sau:
Quy hoạch đô thị:
– Khuôn khổ tích hợp các phân tích đa chức năng vào quy hoạch cơ sở hạ tầng xanh
– Đánh giá lợi ích kinh tế của việc chuyển từ một tòa nhà đơn lẻ sang cách tiếp cận cộng đồng để tái phát triển đô thị bền vững: Nghiên cứu điển hình về khu vực lân cận Lisbon
– Các khái niệm sinh thái cảnh quan trong quy hoạch: xem xét các phát triển gần đây
– Các ngành học thuật và khoa học cốt lõi làm nền tảng cho đô thị bền vững thông minh theo hướng dữ liệu: khuôn khổ liên ngành và xuyên ngành
– Các thành phố bền vững thông minh dựa trên dữ liệu của tương lai: điện toán đám mây và trí tuệ nhân tạo để lập kế hoạch chiến lược, ngắn hạn và liên kết
– Quy hoạch đô thị tính đến nhu cầu của người khuyết tật với các nghiên cứu điển hình
– Ứng dụng quy hoạch và thiết kế đô thị dựa trên công nghệ GIS
– Thiết kế cảnh quan sân vườn đô thị xanh và trải nghiệm người dùng dựa trên công nghệ thực tế ảo và mạng nhúng
– Về thiết kế các thành phố bền vững: ô nhiễm giao thông cục bộ và cấu trúc đô thị
– Cách thiết kế định hình các hành vi lựa chọn không gian trong đô thị công cộng và không gian trong nhà chung
Khoa học và công nghệ trong lĩnh vực kiến trúc, xây dựng:
– Kinh tế tuần hoàn trong ngành xây dựng: Tổng quan về nhận thức của các bên liên quan của Hoa Kỳ, những thách thức chính và các yếu tố thúc đẩy
– Làm thế nào để đổi mới mở nâng cao năng suất? Khám phá hệ sinh thái xây dựng
– Đánh đổi tính bền vững trong việc áp dụng in bê tông 3D trong ngành xây dựng
– Mô hình chia sẻ năng lượng sáng tạo cho các tòa nhà
– Các chiến lược thông gió trong các khu dân cư ở Greenlandic
– Dự báo khoảng thời gian dựa trên mạng nơron về giá vật liệu xây dựng
– Đánh giá môi trường và kinh tế trên các tòa nhà in 3D bằng bê tông tái chế
– Đánh giá vòng đời (LCA) của các cụm công trình tự nhiên và thông thường
– Ảnh hưởng của độ cứng kết nối đến các đặc tính động lực học và hiệu suất địa chấn của các tòa nhà gỗ cao nhiều lớp
– Sự phát triển và viễn cảnh tương lai của cường độ năng lượng trong lĩnh vực xây dựng toàn cầu 1971-2060
– Các vấn đề về thiết kế: những hiểu biết mới về việc tối ưu hóa tiêu thụ năng lượng cho các tòa nhà dân cư
Vật liệu xây dựng:
– Tiềm năng sử dụng tro bã mía làm cát thay thế cho bê tông bền
– Phát triển chất kết dính thủy lực thay thế dựa trên gạch mịn: ảnh hưởng của kích thước hạt và tỷ lệ thay thế
– Sử dụng phụ gia điều chỉnh độ nhớt để giảm sự khuếch tán trong vật liệu gốc xi măng: ảnh hưởng của khối lượng phân tử
– Sợi tre có đặc tính kỹ thuật và hiệu suất phù hợp làm chất gia cường cho hỗn hợp nhựa đường
– Cách tiếp cận mới chống tạo bọt cho vữa bằng phương pháp khoáng sinh học
Xin trân trọng giới thiệu!
QUY HOẠCH ĐÔ THỊ
1. A framework to integrate multifunctionality analyses into green infrastructure planning
Landscape Ecology volume 36, pages1951-1969 (2021)
Green infrastructure (GI) has become an integral part of the process leading toward urban sustainability because it provides multiple ecosystem services that contribute to urban ecosystems and human health. Planners and managers have therefore attempted to understand and improve GI multifunctionality.
This study has characterized and mapped GI multifunctionality in the Fengtai District of Beijing based on the ecosystem services (ES) perspective and has developed an adaptive model to improve its multifunctionality. The study has aimed to: (1) assess and map GI multifunctional degree, (2) characterize GI multifunctional types, and (3) propose adaptive solutions based on characterization of GI multifunctional types.
Biophysical models and social questionnaires were used to quantify and map ES, ES hotspots, and ES bundles to identify the degree of multifunctionality and characterize GI multifunctional types. An adaptive model was designed to improve GI multifunctionality for local planning and design practice.
Three GI multifunctional degrees were mapped, and areas with high multifunctional degree were found to account for only 5.55% of the study area. Seven GI multifunctional types were identified by the distinct heterogeneity of their compositions and function sets. These types of GI also implied different improvement strategies for GI planning and design practice. The adaptive model offers integrated solutions for preserving, restoring, and embedding levels that correspond to the characterization of GI multifunctional types.
The ES-based framework proposed in this paper integrates multifunctionality analyses and can be helpful to urban planners and designers in adaptive GI planning.
2. Evaluating the economic benefits of moving from a single building to a community approach for sustainable urban redevelopment: Lisbon neighborhood case study
Previous studies demonstrated how urban sustainability assessment systems can support the decision-making process to enhance the sustainability performance of an existing urban area. Nevertheless, although these systems were conceived to evaluate environmental, social, and economic dimensions of sustainability, the economic dimension is still underrepresented, particularly in terms of alternative project solutions’ economic feasibility. Therefore, this paper used a neighborhood redevelopment project in Lisbon (Portugal) to propose the economic evaluation of alternative sustainable solutions from single buildings to fully integrated community strategies. For this purpose, it estimated and compared the net present value, the internal rate of return, and the payback time of three alternative renovation strategies: creation of green space areas for urban agriculture; installation of photovoltaic systems; and installation of water harvesting systems. The results showed that community strategies can maximize the economic benefits over time by taking advantage of scale economies and synergies between buildings. In addition, the paper highlighted the possible economic benefits of combining alternative renovation strategies. Finally, it discussed policy and regulatory considerations, providing recommendations for future versions of urban sustainability assessment systems.
3. Landscape ecological concepts in planning: review of recent developments
Landscape ecology as an interdisciplinary science has great potential to inform landscape planning, an integrated, collaborative practice on a regional scale. It is commonly assumed that landscape ecological concepts play a key role in this quest.
The aim of the paper is to identify landscape ecological concepts that are currently receiving attention in the scientific literature, analyze the prevalence of these concepts and understand how these concepts can inform the steps of the planning processes, from goal establishment to monitoring.
We analyzed all empirical and overview papers that have been published in four key academic journals in the field of landscape ecology and landscape planning in the years 2015-2019 (n - 1918). Title, Abstract: and keywords of all papers were read in order to identify landscape ecological concepts. A keyword search was applied to identify the use of these and previously mentioned concepts in common steps of the planning cycle.
The concepts Structure, Function, Change, Scale, Landscape as human experience, Land use, Landscape and ecosystem services, Green infrastructure, and Landscape resilience were prominently represented in the analyzed literature. Landscape ecological concepts were most often mentioned in context of the landscape analysis steps and least in context of goal establishment and monitoring.
The current literature spots landscape ecological concepts with great potential to support landscape planning. However, future studies need to address directly how these concepts can inform all steps in the planning process.
4. The core academic and scientific disciplines underlying data-driven smart sustainable urbanism: an interdisciplinary and transdisciplinary framework
Computational Urban Science volume 1, Article number: 1 (2021)
A new era is presently unfolding wherein both smart urbanism and sustainable urbanism processes and practices are becoming highly responsive to a form of data-driven urbanism under what has to be identified as data-driven smart sustainable urbanism. This flourishing field of research is profoundly interdisciplinary and transdisciplinary in nature. It operates out of the understanding that advances in knowledge necessitate pursuing multifaceted questions that can only be resolved from the vantage point of interdisciplinarity and transdisciplinarity. This implies that the research problems within the field of data-driven smart sustainable urbanism are inherently too complex and dynamic to be addressed by single disciplines. As this field is not a specific direction of research, it does not have a unitary disciplinary framework in terms of a uniform set of the academic and scientific disciplines from which the underlying theories can be drawn. These theories constitute a unified foundation for the practice of data-driven smart sustainable urbanism. Therefore, it is of significant importance to develop an interdisciplinary and transdisciplinary framework. With that in regard, this paper identifies, describes, discusses, evaluates, and thematically organizes the core academic and scientific disciplines underlying the field of data-driven smart sustainable urbanism. This work provides an important lens through which to understand the set of established and emerging disciplines that have high integration, fusion, and application potential for informing the processes and practices of data-driven smart sustainable urbanism. As such, it provides fertile insights into the core foundational principles of data-driven smart sustainable urbanism as an applied domain in terms of its scientific, technological, and computational strands. The novelty of the proposed framework lies in its original contribution to the body of foundational knowledge of an emerging field of urban planning and development.
5. Data-driven smart sustainable cities of the future: urban computing and intelligence for strategic, short-term, and joined-up planning
Sustainable cities are quintessential complex systems—dynamically changing environments and developed through a multitude of individual and collective decisions from the bottom up to the top down. As such, they are full of contestations, conflicts, and contingencies that are not easily captured, steered, and predicted respectively. In short, they are characterized by wicked problems. Therefore, they are increasingly embracing and leveraging what smart cities have to offer as to big data technologies and their novel applications in a bid to effectively tackle the complexities they inherently embody and to monitor, evaluate, and improve their performance with respect to sustainability—under what has been termed “data-driven smart sustainable cities.” This paper analyzes and discusses the enabling role and innovative potential of urban computing and intelligence in the strategic, short-term, and joined-up planning of data-driven smart sustainable cities of the future. Further, it devises an innovative framework for urban intelligence and planning functions as an advanced form of decision support. This study expands on prior work done to develop a novel model for data-driven smart sustainable cities of the future. I argue that the fast-flowing torrent of urban data, coupled with its analytical power, is of crucial importance to the effective planning and efficient design of this integrated model of urbanism. This is enabled by the kind of data-driven and model-driven decision support systems associated with urban computing and intelligence. The novelty of the proposed framework lies in its essential technological and scientific components and the way in which these are coordinated and integrated given their clear synergies to enable urban intelligence and planning functions. These utilize, integrate, and harness complexity science, urban complexity theories, sustainability science, urban sustainability theories, urban science, data science, and data-intensive science in order to fashion powerful new forms of simulation models and optimization methods. These in turn generate optimal designs and solutions that improve sustainability, efficiency, resilience, equity, and life quality. This study contributes to understanding and highlighting the value of big data in regard to the planning and design of sustainable cities of the future.
6. Urban planning for physically disabled people’s needs with case studies
Spatial Information Research volume 29, pages173-184 (2021)
The aim of this study is to provide urban planning procedures tailored to the needs of disabled people. For this, it analyzes the problems of disabled people, especially physically disabled people, for living in Iran’s cities. It also analyses various planning and design characteristics of buildings in Iranian cities. Research methods of this paper are problem-oriented theoretical studies, case studies, a weighted sum method, and a Benchmarking technique. The methods assist to provide relevant standard indicators and a theoretical framework for the comparison of the cities to an optimal alternative. A case study strategy to gather data for certain comparisons and present a disabled-oriented model of urban planning has been performed. The weighted sum method dedicates quantitative scores and performs the comparison and judgment. Finally, this paper concludes that the cities in Iran are not appropriate to the physical and administrative needs of the disabled. This study finds that buildings in Iranian cities often lack the necessary standards for the needs of the disabled. The outcomes of this research concerning urban planning for disabled people will assist better disabled-oriented urban planning, design, and development everywhere in the world.
7. Application of urban planning and design in Yan’an new area based on GIS technology
Arabian Journal of Geosciences volume 14, Article number: 593 (2021)
Based on GIS technology, this paper analyzes the three-dimensional data of urban landforms in Yan’an New District, and studies the problems of mountain terrain in Yan’an new area as a whole, the difficult problems in terrain reconstruction, the location of water system in the new area, and so on. The landscape vision and dynamic three-dimensional visualization of planning results in the new area. The planning of new area has real-time interactive feedback with GIS technology in the whole stage from planning conception, sketch to final scheme expression, which is really combined with the scheme design, which provides help in real-time adjustment and modification of the scheme. This method of decomposing urban planning problems into GIS processing and establishing corresponding models and making planning suggestions can become an application mode to solve planning problems in the future.
8. Green urban garden landscape design and user experience based on virtual reality technology and embedded network
Environmental Technology & Innovation, Available online 29 June 2021, 101738
With the development of electronic science and technology, green landscape planning and design in urban landscape design has become a new trend and direction. The emergence of virtual reality assisted design technology and platforms has brought more innovation space for landscape designers and greatly reduced Time and workload. The mature application of virtualization technology and embedded network technology in various fields provides technical support for perfecting the concept of virtual reality. Based on virtual reality technology and embedded network, this thesis discusses green urban garden landscape design, and constantly strengthens user experience, expands the extension of garden landscape design. On the one hand, the development of virtual reality technology and embedded network makes garden landscape design the imagination of the teacher can be brought into play and realized. On the other hand, in the virtual scene, the landscape architect integrates the characteristics of different types of elements to design creative and innovative, open and shared garden landscapes. Using the Internet platform as a medium, refer to and learn from more representative works, and stimulate more creative landscape design concepts.
9. Simplified evaluation metrics for generative energy-driven urban design: A morphological study of residential blocks in Tel Aviv
For almost two decades, the Zero Energy Buildings (ZEB) standard has epitomized a commitment to the high energy performance of buildings. Nevertheless, the applicability of ZEB in hot climates is currently limited and furthermore, in light of the current limitations of traditional building energy modeling methods, new methods are necessary to effectively evaluate the energy balance potential of larger districts. To help bridge this gap, this paper introduces solar-based (both sun-hours and solar irradiation) and geometry-based prediction metrics to be used in optimization studies to evaluate the impact of urban morphology on the energy balance of residential blocks in hot urban contexts. These prediction metrics are derived from the simulated energy performance of 1,944 parametric variations of residential blocks in Tel Aviv. In a regression analysis, these metrics recorded high correlation with energy demand, energy supply and the balance between them. To test the applicability of these metrics for optimization, the RBFMOpt method is employed in a multi-objective optimization study of the energy supply and demand of a nine-block residential district in Tel Aviv. Detailed energy simulations are performed for the best non-dominated results from the solar and geometric optimization studies and compared to the non-dominated results from a full energy optimization run. The results indicate that these metrics – the solar and geometric area-weighted exposure and shading indices – can serve as effective energy performance indicators to inform early-stage morphological decisions making. This workflow promotes urban energy optimization towards more harmonized energy supply and demand driven approaches.
10. Research on digital urban architecture design based on cloud computing data center
With the acceleration of China’s urbanization process, the scale of cities continues to expand, and urban management issues are becoming increasingly prominent. This research takes the application of digital urban management integration as an example, designs the digital urban management subsystem, combines the design of the system framework, data layer, and integrated public platform layer, and analyzes the data function process of the digital urban management subsystem. Digital cities, as proven by practice, can effectively solve many problems of urban management. The continuous breakthrough of cloud computing has laid a solid foundation for the development of digital cities. The purpose of this article is to study the construction of digital cities based on cloud computing data centers. This article outlines the basic concepts of digital cities, studies related technologies of cloud computing, and introduces related technologies of data transfer in digital cities. Based on the background of digital city construction, a digital city system framework based on cloud computing data center is proposed. Based on the system framework, a digital urban management integrated application system is designed. The test proves that the integrated system can meet the performance requirements of daily business processing. In this paper, the average transaction response time is less than 5 s and the application server utilization is less than 80% as evaluation indicators. By testing the performance of the system, the average response time is 0.436 s and the average CPU utilization is 58.25%
11. A multi-method approach to design urban logistics hubs for cooperative use
Limited availability of public space and high urban property prices make shared logistics solutions highly attractive. The objective of this paper is to offer guidance on the best way to design urban logistics hubs for cooperative use by different courier-, express and parcel service providers (CEPs). The present research used a set of different methods to collect a substantial amount of qualitative and quantitative data. The example of Vienna (Austria) offers real-world data. The research paper identifies suitable attributes for describing different CEP user types and uses a linear optimisation model to suggest an optimal allocation of the shared infrastructure capacity. The optimisation model aims to maximise the total utility of hub space utilisation throughout an average working day. It assumes that the utility increases with the hub’s occupancy rate and the convergence of its CEP user types with the administration’s and the citizens’ vision of future city development. The results show that involved stakeholder groups – i.e. CEPs, citizens and city administrations – have both, conflicting and common goals.
12. Economical energy resource planning to promote sustainable urban design
This paper explores the economic aspects of distributed energy sources in a given neighborhood development. A novel methodology is proposed to achieve optimal synergy among renewable and alternative energy resources while accounting for economic and technical constraints. The methodology aims to achieve positive annual revenue to recover the capital cost investment in renewable energy, in minimum payback period. The methodology is demonstrated for a mixed-use neighborhood case study considering various scenarios of energy systems. The work proposes various tariff schemes combined with an optimal energy resource planning strategy to maximize the yearly revenue. Implementing the proposed methodology, a least payback period can be determined to address investment-related challenges faced by net-zero energy developments. The methodology allows to explore multiple near optimal combinations. Selection can be made employing suitable criteria based on specific conditions such as investment opportunities or expected minimum payback. For instance, in the demonstrated case study, a minimum payback period of 15.2 years can be achieved using non-electrical equipment (mixture of natural gas, waste-to-energy, thermal storage and grid) for space heating and domestic hot water. In this optimal case scenario, a logarithmic-based tariff scheme yields the best results.
13. Computer simulation of urban garden landscape design based on FPGA and neural network
Digital Landscape is a combination of the system and the computer software and hardware system of a high simulation model. The author analyzes the application of computer simulation in landscape design and value analysis of a city garden. In the computer-aided design, the importance of digitizing information in the landscape design process, mainly human and the interaction of computer, is reflected in the digital model’s creation and multimedia performance, becoming more and more evident. To form a two-dimensional or three-dimensional spatial data, to realize real-time, statistical Analysis, using the human living environment, multi-dimensional, efficient, and humane, and environmental landscape plan to more rational and practical, used the computer simulation techniques. Effective use of urban rainwater, to reduce the flooding of urban areas, it is possible to alleviate the water crisis, the organic combination of rainwater can be used in the course of the construction of the urban landscape as well as make-up landscape, visual beautification has optimized the ecosystem, and from many rainwater utilization functions; These functions in landscape design, rainwater garden, It can be realized the rooftop garden, and the city’s green. The construction and sustainable economy and the promotion of the ecological park’s social development will positively sign. Suitable for rainwater regulation, water (recovery) is stored – Computer-Aided Design (CAD) green space. Technical measures save of suggestions for practical application of the square: innovation and new of space design, new artificial wetland system, and garden rainwater in the application of the regulation (population) storage system design of the water-saving of these to the sustainable development of such new square of rainwater adjustment (group) storage system design and urban landscape environment. It is useful for the application of technology.
14. Climate-informed decision-making for urban design: Assessing the impact of urban morphology on urban heat island
Urban growth is related to major environmental consequences and affects people’s livability and economy. To address such impacts, stakeholders must evaluate different mitigation policies. Due to the complexity of those phenomena, such comparison process can be challenging, resulting in subjective and unclear interpretations, which consequentially limits the course of action for its implementation. To overcome this difficulty, we develop a novel framework that provides a statistical analysis of urban climate models. The high-dimensional data generated by the climate model is transformed into a low-dimensional scoring system, according to statistical metrics that reflect desired priorities of stakeholders. This allows for informed quantification of the quality of different scenarios by policy makers. We illustrate the applicability of the framework in an urban area of Singapore. Different urban morphologies are analysed, estimating their environmental impact on Urban Heat Island and their potential for population allocation, while considering operational energy costs. The result is a matrix of scores per scenario, highlighting the optimal design according to the pre-defined metrics. The scenarios with the highest building height (81 m) and medium (40%) or low (30%) density offer a good balance between the environmental impact and its external trade-offs, evaluated by the number of people allocated per site area and the cost of energy to operate the district.
15. Urban microclimate and its impact on building performance: A case study of San Francisco
Urban microclimate exerts an increasing influence on urban buildings, energy, and sustainability. This study uses 10-year measured hourly weather data at 27 sites in San Francisco, California, to (1) analyze and visualize the urban microclimate patterns and urban heat island effect; (2) simulate annual energy use and peak electricity demand of typical large office buildings and large hotels to investigate the influence of urban microclimate on building performance; (3) simulate indoor air temperature of a single-family house without air-conditioning during the record three-day heatwave of 2017, to quantify the divergence of climate resilience due to urban microclimate effect. Results show significant microclimate effects in San Francisco with up to 11 °C outdoor air temperature difference between the coastal and downtown areas on September 1, 2017, during the record three-day heatwave. The simulated energy results of the prototype large office and large hotel buildings using the 2017 weather data show over 100% difference in annual heating energy use and 65% difference in annual cooling energy use across different stations; as well as up to 30% difference in peak cooling electricity demand. The impacts on annual site or source energy use are minimal (less than 5%) as cooling and heating in a mild climate are a relatively small portion of overall building energy use in San Francisco. Results also show the microclimate effects influence indoor air temperature of unconditioned homes by up to 5 °C. Newer buildings and homes are much less affected by microclimate effects due to more stringent performance requirements of the building envelope and energy systems. These findings inform that San Francisco microclimate variations should be considered in urban energy planning, building energy codes and standards, as well as heat resilience policymaking.
16. Evaluating the applicability of Typical Meteorological Year under different building designs and climate conditions
Typical year weather files are synthetic files generated from historical weather data used in building energy simulation to evaluate energy performance of buildings. The current work is to illustrate the impact of building types and designs on the deviations between the energy demand predicted using typical year weather files and the average energy demand predicted using 30-year long-term actual year weather data. This study explores design parameters, which have great impact on energy demands, including window-to-wall ratio, window solar heat gain coefficient, floor construction, and solar reflectance of exterior walls and roof. These design parameters are applied to two different building types – small and large office buildings, and two different climatic locations- Montreal and Vancouver, Canada. The results indicate that certain designs exhibit wider deviations between energy demands predicted with a typical year and the long-term average. The maximum deviation is found to be around 4.5%, which suggests that typical year weather file is still a reliable means to predict the long-term average cooling and heating energy performance. However, the study also found that typical year weather files underestimate the peak load in the long run for up to 85% of the time.
17. Urban rail service design for collaborative passenger and freight transport
Transportation Research Part E: Logistics and Transportation Review, Volume 147, March 2021, 102205
This paper develops an operational strategy in which urban rail transit is used for freight transport. An environment-friendly urban freight transportation alternative is analyzed by employing optimization techniques to support the collaborative transportation of passengers and freight. Practical cases are investigated to test the technical feasibility of this transportation scheme. The paper formulates the train service design problem on a single urban rail line with passenger and freight. Passenger trains have a prescribed timetable which is allowed to be slightly modified to facilitate the freight service. Freight can be transported by inserting dedicated freight trains or utilizing the extra space inside the passenger train carriages. Station platforms are able to load and unload both goods and passengers. An optimization model for combined train service design is proposed to maximize profit resulting from the balance of revenues and costs brought by the freight service. The efficient schedules of trains and freight allocation plans are to be determined. This problem is formulated as a mixed-integer linear programming model. An iterative scheduling approach which includes a pre-processing method and two heuristic iterative algorithms is designed to solve the model. Two numerical examples are introduced to demonstrate the efficiency of the proposed model and the iterative scheduling approach.
18. Occupant behavior modeling methods for resilient building design, operation and policy at urban scale: A review
Traditional occupant behavior modeling has been studied at the building level, and it has become an important factor in the investigation of building energy consumption. However, studies modeling occupant behaviors at the urban scale are still limited. Recent work has revealed that urban big data can enable occupant behavior modeling at the urban scale – however, utilizing the existing data sources and modeling methods in building science to model urban scale occupant behaviors can be quite challenging. Beyond building science, urban scale human behaviors have been studied in several different domains using more advanced modeling methods, including Stochastic Modeling, Neural Networks, Reinforcement Learning, Network Modeling, etc. This paper aims to bridge the gap between data sources and modeling methodologies in building science by borrowing from other domains. Based on a comprehensive review, we 1) identify the modeling challenges of the current approaches in building science, 2) discuss the modeling requirements and data sources both in building science and other domains, 3) review the current modeling methods in building science and other domains, and 4) summarize available performance evaluation metrics for evaluating the modeling methods. Finally, we present future opportunities in building science with enhanced data sources and modeling methods from other domains.
19. Competitiveness, distinctiveness and singularity in urban design: A systematic review and framework for smart cities
Should smart city applications reconsider the principles of placemaking in confronting the resemblance of smart cities? This systematic review seeks to answer this question by offering a framework that elucidates the principles of placemaking in smart cities and the relationship between people and places. The results of reviewing the SciVal and SCImago databases yielded 13 journals related to ‘urban economy’- as a goal of smart cities-and ‘placemaking’- as a target of city singularity. A random selection of 44 articles in these journals was conducted based on the presence of words in titles, Abstract:s and keywords between 2012 and 2020. Four terms were revealed, namely, competitiveness, distinctiveness, urban forms and everyday lifestyles. The findings compiled 22 principles for creating singularity among smart cities. The three-step framework for creating the singularity of smart cities provides insights into how urban actors and stakeholders in the Global South can change traditional smart cities by aggregating the principles of placemaking (i.e. urban forms and everyday lifestyles) with the principles of the urban economy through urban competitiveness and distinctiveness. The conclusions suggested revisiting factors of ranking smart cities by considering the principles of placemaking, which can enhance the singularity of smart cities.
20. Train service design in an urban rail transit line incorporating multiple service routes and multiple train compositions
Transportation Research Part C: Emerging Technologies, Volume 123, February 2021, 102959
This paper focuses on the train service design problem within a given period in an urban rail transit line, where multiple either full-length or short-turn service routes can be operated, and each service route can utilize one of several different train compositions. The problem lies on determining the turn-back stations, train composition and frequency of each service route operated on the line. Considering the interests of operators and passengers, we decompose the problem as two subproblems namely train service configuration and passenger assignment. The first subproblem is formulated as an integer linear programming model with the objective of minimizing operators’ cost. Given a train service scheme, the second subproblem is modelled as a capacitated continuous multi-commodity flow model to minimize passengers’ waiting time cost and transfer cost. The optimal strategy is extended to determine the behaviour of passengers and capture the extra waiting time of passengers under capacity constraint. The two sub-models are weighted and integrated into a mixed integer nonlinear programming model, which is further transformed into a mixed integer linear programming model using a novel linearization method. By exploiting the special characteristics of the model, a tailored and easy to implement local search algorithm is developed to solve large-scale instances. Starting from the operator-optimum solution which can be easily obtained, the algorithm solves the two sub-models iteratively to search better solutions within a precalculated search range which is smaller than the complete feasible domain. Finally, different sizes of instances constructed from two urban rail transit lines are utilized to demonstrate the performance and practicability of the proposed approaches.
21. On the design of sustainable cities: Local traffic pollution and urban structure
This paper investigates the impact of local traffic pollution on the formation of residential and business districts. While firms benefit from local production externalities, households commute to their workplaces with private vehicles and exert a local pollution externality on the residents living along the urban transport networks. The spatial location of firms and residents endogenously results from the trade-off between the production and pollution externalities and the commuting costs. The analysis shows that in monocentric cities the benefits associated with a fall in per-vehicle pollution are absorbed by rents paid to absentee landlords. When a city includes business and residential districts as well as a district mixing both agents, a lower per-vehicle pollution enlarges the residential districts and shifts the business districts closer to the geographical center of the city. The paper finally studies the optimal city structure. The first-best policies that fully internalize the externalities still foster business agglomeration.
22. How design shapes space choice behaviors in public urban and shared indoor spaces – A review
This systematic literature review synthesizes the major physical and socio-physical determinants on space choice behaviors in open (i.e., non-defined uses) versus enclosed (i.e., specific uses defined) spaces. The purpose is to better understand the trade-offs between open and enclosed spaces and how opposing and complimentary design elements influence behavior and occupancy choices. Using the lens of space choice behaviors, we hypothesize that similar design challenges exists at both scales, and that analogous insights can be applied to both urban planning and building design. We analyze the focus areas, research drivers, locations, and methods applied in the reviewed studies, and find overlapping similarities within research at both scales, particularly in the methods applied. The drivers for research into buildings tend to be more about optimizing space allocation, whereas lifestyles and well-being are more common in urban studies. We synthesize the content of the literature and find that challenges of successful public and common spaces in cities and buildings are similar in terms of trade-offs, barriers, and impacts on user activities. The implementation of diverse open spaces create more flexibility and adaptability to changing trends, attract different interest groups, and ultimately provide more synergistic benefits to the use of buildings and cities.
23. Urban environment art design simulation based on FPGA and neural network
Environmental process and compositions of the interior and exterior spaces period, outside the species is a continuation of mixing. Ability to Cities Climate Progress Street Development (CCPSD) under development and urban ecosystem is of great interest. Like the collaborative process, the chemical composition and natural finish edge has appeared on the stage. Urban development is inseparable from the appearance of human experience, a more complete overall climate. Gradually different base and current methods of life living material, natural integration plan needs a metropolitan area, then specific social nature and philosophy of environmental protection of the city, and more thoughts. In this article, method will focus on metropolitan areas the natural clear plan to complete the examination. Set best-effort edge within the metropolitan area to explicitly check liner Field Programmable Gate Array (FPGA). The purpose and work planning and layout of the system need to be considered.
KHOA HỌC VÀ CÔNG NGHỆ TRONG LĨNH VỰC KIẾN TRÚC, XÂY DỰNG
1. Permeable pavement design framework for urban stormwater management considering multiple criteria and uncertainty
Cities worldwide continue to face severe water management problems. Therefore, researchers have endeavored to study stormwater management alternatives. However, the uncertainties in the outcomes of such scenarios and the inherent vagueness in human judgment are seldom considered in stormwater-related decision-making. Accordingly, this study developed a fuzzy analytic hierarchy process (FAHP) framework for designing permeable pavements, mainly comprising hydrologic, hydraulic, water quality, and economic criteria. The inputs and outputs were fuzzy instead of crisp numbers, to account for uncertainties. To illustrate the framework, a campus in Shanghai, China, was chosen as a case study. First, five permeable pavement design scenarios (SC1–SC5) were developed. The differences between SC1–SC3 were in the vehicle lanes, whereas those among SC3–SC5 were in the other light-load roads. Subsequently, expert opinion and stormwater management model (SWMM) simulation results were used as inputs to the framework. The results suggest that permeable pavements can effectively reduce surface runoff and pollutants but may lead to an increase in the conduit peak flow, owing to a reverse flow. In addition, adopting permeable pavements on vehicle lanes is less cost-effective than adopting them on light-load roads. Scenario SC5, which applied permeable pavements to 26% of the study area, was found to offer significant hydrologic, hydraulic, and water quality advantages over the other scenarios.
2. Circular economy in the construction industry: An overview of United States stakeholders’ awareness, major challenges, and enablers
Increasing environmental concerns and resource scarcity risks have drawn attention to a Circular Economic (CE) model during the last decade. Nevertheless, literature related to the state of practice of CE in the built environment in the United States (U.S.) is still limited. In this context, this study investigates U.S. architectural, engineering, and construction (AEC) industry stakeholders’ awareness of CE. The investigation also covers major barriers for the implementation of strategies aligned to the CE model, and enabling factors for a transition from a linear economic model to a CE model in the construction industry in the U.S. A mixed-methods approach was deployed through a combination of online survey and interviews with AEC industry stakeholders from different regions of the U.S. Results revealed that some strategies are widely disseminated (i.e., open-loop recycling, selective demolition, and prefabrication), whereas others are hardly adopted (i.e., design for disassembly, design in layers, closed-loop recycling). Additionally, findings indicate budget and upfront costs, project schedule and timeline, lack of awareness and regulations, and current business models as major barriers for the implementation of strategies aligned to a CE model. Furthermore, four enabling factors for a transition to a CE model in the construction industry were identified (i.e., education and cultural change, data availability, policies and incentives, and novel voluntary stewardships). Notably, contributions of this study include fostering a much needed debate around circular construction and its challenges, and expanding the limited existing body of knowledge.
3. How does open innovation enhance productivity? An exploration in the construction ecosystem
The innovation literature on operations-based organisations describes the positive effect of Open Innovation (OI) on productivity. However, a systemic overview of how OI directly and indirectly impacts productivity is missing, particularly for project-based organisations. Hence, the article aims to fill this gap by providing a systemic representation of how OI enhances project-based organisations’ productivity. The article focuses on the construction ecosystem since construction is an exemplary project-based industry and is known for its widespread and longstanding poor productivity. In particular, we investigated how OI is adopted and how OI can enhance productivity in the construction ecosystem. We conducted twenty semi-structured interviews with experts involved in OI construction projects in the UK. This paper makes three academic contributions. First, it provides an account of the most relevant causes for poor productivity in construction. Second, it consolidates primary and secondary data in a novel cognitive map providing a systemic representation of how OI enhances productivity in construction. The validity of the map goes beyond the boundaries of the construction ecosystem, being supported by several cross-sectorial references. Third, the paper offers six strategies that leverage OI to address the specific causes of low productivity in construction.
4. Sustainability tradeoffs in the adoption of 3D Concrete Printing in the construction industry
In recent years, 3D Concrete Printing (3DCP) has gained traction as a technological solution for reducing cement production’s hefty carbon footprint. Studies assessing the sustainability benefits of 3DCP have not included its impact on social sustainability, nor how construction firms’ implementation of this new technology has affected its success. This study applies grounded theory methods to analyze the tradeoffs between environmental, economic, and social sustainability, and how firms’ decisions impact these tradeoffs. We gather insights from 20 interviews with 3DCP pioneers in Central and Northern Europe. Our findings suggest that firms’ greatest incentive to invest in the technology is not related to the environmental benefits, but rather 3DCP’s potential to increase automation and combat the current shortage of skilled labor in the construction sector. Current government procurement rules do not reward sustainability benefits sufficiently to encourage the uptake of 3DCP. Based on our findings, we identify five strategic decisions that companies make which affect 3DCP’s sustainability, and discuss opportunities for government to foster the adoption of this technology.
5. Innovative power-sharing model for buildings and energy communities
The paper proposes an innovative power-sharing model, i.e., a power-system architecture for aggregation of users able to share the power produced by common generators and energy services. The model is suitable for both multi-tenant buildings and groups of multiple buildings and it is applicable for both existing and new buildings. It is scalable for larger systems and suitable for an easier integration with storage systems. The novel principle of the model is that the energy produced by common generators can be shared among the end-users in a unidirectional way, so that each user remains passive towards the distributor, except a single active user that assumes the role of balance node. This key feature allows for easily implementing the model in all the residential and tertiary multi-units buildings in full compliance with national regulations, with the adoption of power sharing contracts as well. This paper discusses the feasibility of the model through a dynamic Matlab/Simulink model, which is used to show its effectiveness in several case studies. The significance of this work consists of approaching the energy sharing in buildings with a completely new strategy, based on an innovative system architecture that can be effectively implemented.
6. Energy performance of phase change materials integrated into brick masonry walls for cooling load management in residential buildings
Energy demand for space cooling in residential buildings is projected to witness rapid growth, primarily fueled by increasing household incomes in developing countries. To manage this ever-increasing cooling demand, integration of phase change materials (PCMs) in building walls is a potential solution that can reduce the buildings’ cooling energy consumption and peak cooling loads. However, to attain the proposed benefits from PCM integration, it is crucial to appropriately select PCM parameters such as its phase-change temperature and positioning in the wall. Thus, this investigation studied the energy performance of PCM integrated brick masonry walls for cooling load management in residential buildings under periodic steady-state conditions to identify the parameters that govern its performance and develop simple design guidelines.
The research found that regardless of the amount of latent heat stored by the PCM, the daily heat gains and cooling loads were equal for wall configurations having equal thermal resistances under identical boundary conditions. Furthermore, even with the application of night ventilation, adding a PCM layer to a well-insulated wall did not reduce its cooling load; thus, PCM integration was ineffective in reducing the cooling load. However, the latent heat stored by the PCM reduced the fluctuations in the hourly heat gains and cooling loads; thus, PCM integration was found suitable for peak load management. For the PCM’s proper utilization, its recommended position is on the inner side of the wall with sufficient insulation shielding it from outdoor conditions, and its melting temperature should be close to the indoor set-point temperature.
7. Performance-based seismic assessment of capacity enhancement of building infrastructure and its cost-benefit evaluation
Excessive damage to building infrastructure has been witnessed in some major earthquakes in Pakistan and hence requires to better understand their potential vulnerability. Some basic data was gathered in terms of features such as number of stories, age of building and construction typology, as a part of this study to evaluate seismic risk in Abbottabad city (in the North of Pakistan), Relevant study is scarce in the literature so far on the vulnerability study of Pakistan building infrastructure with and without strengthening (capacity enhancement), using performance based seismic assessment methodology. This is first of its kind of study done on the structures in Pakistan that describes the different attributes and performance in detail. To measure the seismic vulnerability of building infrastructure, the induced damage due to increased shaking force is determined. This description of the structure’s vulnerability, in conjunction with the hazard, permits well informed, risk-based conclusions that can be done using performance metrics for instance collapse prevention and economic effects. Numerical modeling was performed by using available data, collected during field survey to represent exactly, the actual response of building infrastructure. Two sets of building fragility curves, before and after capacity enhancement (strengthening), are employed to describe the seismic behavior of the building infrastructure in all the cases. To calculate the losses, an inventory was composed using field survey data that contains all the structural and non-structural components.
8. Current ventilation strategies in Greenlandic dwellings
The Arctic winters are long and cold. When temperatures drop deep below freezing point, the occupants of Arctic dwellings become hesitant to opening windows in order to avoid cold draught. Natural vents are typically sealed. Mechanical ventilation is either not existing or comprises of bathroom fan and range hood. Air tightening of the building envelope to prevent draught results in a lack of makeup air for the extraction fans. This leads to further reduction of air change in majority of the dwellings. One consequence is poor indoor air quality. The other may be moisture levels high enough to damage the construction. The current Greenlandic building code does not require use of complex ventilation systems. Lack of experience and requirements together with higher construction costs will typically cause ruling the complex mechanical ventilation systems out of the projects and replacing them by bare minimum. In this project we mapped, three ventilation solutions. Two renovations and one new home. The measurements have shown that the IAQ (evaluated based on CO2 and humidity measurements and occupant interviews) had improved significantly with use of balanced mechanical ventilation with heat recovery. The occupants have reported increase in their comfort. The systems were capable of continuous operation throughout the Arctic winter. Installation of the mechanical ventilation had proved to be an efficient solution to IAQ problem in Greenland.
9. Neural network-based interval forecasting of construction material prices
Accurate prediction of material costs is essential for proper management and budgeting of construction projects. Material price fluctuation is one of the most important contributors to deviations from the initial estimated cost in construction projects. Traditional machine learning techniques often fail to generate accurate predictive estimates due to high uncertainties associated with material prices. To address this issue, this research proposes an artificial neural network (ANN)-based method to quantify uncertainties through the generation of forecasting intervals. The optimal lower upper bound estimation (optimal LUBE) method is adopted to train ANN to generate intervals directly. The proposed method is used to predict construction material prices in the US for asphalt and steel. It is shown that traditional regression analysis and ANN-based single-point estimates are of limited value for the prediction of material price. In contrast, prediction intervals provide reliable estimates for material prices and they reduce the possibility of project failure due to the inaccuracy of initial estimated costs. The results obtained from three other cost functions are compared to the proposed optimal LUBE cost function to testify the accuracy of the model. The achieved results show that the proposed optimal LUBE cost function presents the most accurate prediction intervals. This study employs a stacking procedure for monitoring and controlling the training process and validation purpose. The proposed interval forecasting method presents a new direction for cost prediction studies and will provide project managers with extra information to manage risks associated with project costs.
10. The role of bacterially induced calcite precipitation in self-healing of cement paste
Self-healing processes in cementitious materials have been intensively studied in recent years. They present a promising way to increase the durability of concrete and extend the service life of concrete structures, thus mitigating the impacts of the construction industry on public budgets and the environment. The role of bacterially induced calcite precipitation (BICP), the basis of one of the processes, is not fully understood yet, even though many researchers have reported improved mechanical properties or water tightness of cracked cementitious composites self-healed in the presence of bacteria. Therefore, the authors of this paper are focused on detailed characterization of BICP with the purpose of determining the direct impact of bacteria on the self-healing in cement composites. Three different bacterial strains, namely Sporosarcina pasteurii (SP), Bacillus cohnii (BC) and Bacillus pseudofirmus (BP) were studied. Their viability and metabolic activity in optimal and sub-optimal conditions were compared. Several analytical methods (XRF, TGA, TCD, FTIR) were used to characterize the attainable BICP depending on the particular strains. BP proved to be the most suitable bacterium, showing excellent viability and sufficient calcite production, even in sub-optimal conditions (10 °C temperature). Microscopic analysis of the self-healing products in artificially cracked cement paste showed that the application of BP with precipitation media lead to complete sealing of the crack by very dense calcite crystals (less than 1 μm), while porous structure of larger crystals (up to 30 μm) was formed in reference samples not treated with the bacteria, where only spontaneously induced calcite precipitation (SICP) occurred. As a result, it was proved that the bacteria directly contribute to the self-healing of cementitious materials and that BICP leads to the formation of a superior crack-sealing material.
11. Behavior of steel-reinforced composite concrete columns under combined axial and lateral cyclic loading
This study presents the experimental and numerical investigations on structural steel-reinforced concrete (SRC) columns under combined axial and lateral cyclic loadings. The main parameters evaluated are the peak lateral strength, mode of failure, hysteretic response, stiffness degradation, and energy dissipation potential of SRC columns. A parametric study has been conducted using a finite element software ABAQUS to predict the flexural capacity of the SRC columns under varying axial load levels and to evaluate the reliability of the design guidelines of Eurocode 4 (2004) and AISC 360-16 (2016) in predicting the axial load (P) – bending moment (M) interaction behavior of SRC columns. In the tension damage regions, the experimental and numerical data points mostly lie within or on the unfactored P-M envelopes of both these standards. However, the data points are found to fall outside the P-M envelopes in the compression damage region. For the SRC columns designed to fail in the compression damage, the Eurocode 4 (2004) provisions showed a more reliable prediction of the failure loads under the uniaxial bending condition.
12. Bacterial crack healing in metakaolin based geopolymer mortars
Geopolymer mortars have emerged as an environmentally friendly binding alternative to conventional cement. However, the gaps in their structure and early cracks reduce their service life. There are various bacterial healing studies in the literature that have been conducted on cemented mortar cracks. Nevertheless, the present study focuses on the healing of metakaolin based geopolymer mortar cracks.
For this purpose, mortars with different molarities were prepared with two different endospore forming methods that did not require encapsulation or mixed chemical processes for the bacterial crack repairs on the geopolymer mortars. These mortars were then left in different healing environments with crack damage. The samples were tested using physical, optical and internal structure analyses. As a result, the cracks were improved by reducing the amount of gaps in the samples. The results showed that it is possible to bacterially repair early cracks in new generation ceramic materials with alkali-activated mortars and reduce the amount of gaps.
13. Life cycle carbon emission reduction potential of a new steel-bamboo composite frame structure for residential houses
To understand the carbon emission reduction potential of residential houses, life cycle assessment needs to be considered for different building designs. In this context, this study compares the life cycle emissions of a new steel-bamboo composite frame structure with a general reinforced concrete frame structure associated with a rural detached house in East China. Based on the inventory analysis of the production, construction, operation, and end of life phases, a process-based method is adopted to assess the emissions and a Monte Carlo simulation is conducted to investigate the influences of parameter uncertainty on the comparison. The results show that life cycle emissions of the steel-bamboo and concrete frame structures are 440.6 tCO2e and 537.4 tCO2e, respectively. Although the operation phase is the largest contributor, the production phase accounts for up to 36.4% of the total emissions. The contribution coefficients of desired processes indicate that cooling, heating, and lighting are influencing factors for the emissions of both structural schemes, whereas production of galvanized steel sheet and bamboo scrimber should be underlined to reduce emissions from the steel-bamboo structure. Based on an uncertainty analysis using 10000 simulation iterations, the 95% confidence interval of emission reduction in the steel-bamboo structure is estimated as [21.0, 155.0] tCO2e. this result verifies that the steel-bamboo structure is more “carbon-friendly” than a general concrete frame structure. Moreover, this study proposed suggestions to improve the life cycle carbon reduction potential and can help to understand the influences of structural designs on the sustainable development of residential houses.
14. Sustainable material choice for construction projects: A Life Cycle Sustainability Assessment framework based on BIM and Fuzzy-AHP
Construction professionals and researchers are increasingly looking for sustainable solutions for buildings in a bid to reduce some of the negative impacts associated with the sector. A common misconception is to consider sustainability as only concerning environmental issues, without regard for the interaction between a triple bottom line framework that is comprised of social, economic, and environmental factors. Material choice is known to impact building sustainability directly since the use of certain materials can dramatically alter the footprint generated over the life cycle of the building. However, the construction industry is not yet equipped with approaches that simultaneously account for all three aspects of sustainability when it comes to deciding on materials to adopt. This paper proposes a decision-making framework for construction professionals and researchers involving the integration of Life Cycle Sustainability Assessment (LCSA), Multi-Criteria Decision Analysis (MCDA), and Building Information Modeling (BIM) to choose suitable materials for buildings. The framework is built based on a literature review of relevant papers to identify critical factors and challenges to implementing this integration. The Fuzzy Analytic Hierarchy Process was chosen as the MCDA method within the proposed framework, given that the problem of material choice often contains subjectivity, uncertainty, and ambiguity, which is best solved with fuzzy logic. A residential building was adopted as a case study to validate the proposed framework, and the LCSA method is applied, covering the construction, operation, and end-of-life phases of the building.
15. A circular construction evaluation framework to promote designing for disassembly and adaptability
Journal of Cleaner Production, Available online 29 June 2021, 128122
This paper formulates a concise, free-to-use Circular Construction Evaluation Framework (CCEF) based upon international design code guidelines to assess and quantify the circularity credentials of an existing or proposed construction project. Central to the principles of circular construction is designing for disassembly and adaptability – the ability of a building’s elements and connecting components to be disassembled and reused, or rearranged, after the initial design life. Analysis of modern methods of construction and the compatibility of systems with the concepts of designing for disassembly and material reuse inform the development of the CCEF. Circular construction is facilitated by simplicity, standardisation and modularity in design, sustainably-sourced materials, transparent and accessible mechanical connections and the adoption of a manufacturing-style approach towards durable and reusable standardised components and materials. The CCEF allows users such as clients, consultants, contractors, local and national planning and infrastructure policy professionals to evaluate both whole building and elemental levels at the early design and planning stages in a new-build, refurbishment or renovation project. Implementation of a scoring system is demonstrated by the evaluation of example buildings with varying usage of conventional and bio-based materials. It is shown by use of the framework that a simple standardised construction using reversible connections and previously used material elements rates highly, demonstrating a greater extent of circularity in the construction.
16. Recycling potential in building energy renovation: A prospective study of the Dutch residential building stock up to 2050
Building energy and construction and demolition waste (CDW) are highly relevant but intertwined issues for the transition towards a carbon-neutral and circular built environment. Ongoing energy renovation uses an increasing number of emerging materials that pose a challenge for recycling. As a response, a novel technological system has been proposed to recycle CDW (including insulation mineral wool and lightweight concrete) for the manufacture of prefabricated concrete elements (PCEs) for use as façades for new (PCE-new) and retrofitting existing (PCE-refurbs) buildings. To explore how this novel system can improve recycling potential as part of building energy renovation efforts, the Dutch residential building stock was selected as a case study. Using a dynamic material flow analysis, we explore the supply-demand balance of secondary raw materials made from CDW (including normal-weight and lightweight concrete, glass, insulation mineral wool, and steel) and the secondary raw materials required for manufacturing PCEs in building energy renovation for the period 2015–2050. Our findings show that with advanced recycling technology, the secondary raw materials recovered from normal-weight concrete waste, glass waste, insulation mineral wool waste, and steel scrap will be more than sufficient to support the manufacturing of PCE-new walls, implying the possibility of closed-loop construction. However, for emerging materials such as lightweight concrete, the related waste will not be sufficient in the near future to meet the raw material demand for large-scale refurbishment with PCE-refurbs. Therefore, the Dutch case shows that the novel technology system offers a promising solution to CDW management problems in building energy renovation, but primary raw materials will still be needed for the increased use of emerging materials such as lightweight concrete.
17. Revisiting the effects of prefabrication on construction waste minimization: A quantitative study using bigger data
Prefabrication has long been recognized as a green production technology to minimize construction’s adverse environmental impacts such as waste, noise, dust, and air pollution. Previous studies reported the effects of prefabrication on construction waste minimization. However, these studies relied primarily on small data obtained by ethnographic methods such as interviews and questionnaire surveys. Research to evaluate the effects using bigger, more objective quantitative data is highly desired. This research aims to re-evaluate the effects of prefabrication on construction waste minimization by exploiting a quantitative dataset stemmed from 114 sizable high-rise building projects in Hong Kong. It was discovered that the average waste generation rates of conventional and prefabrication building projects were 0.91 and 0.77 ton/m² respectively. Compared with conventional construction, prefabrication logged a 15.38% waste reduction. Further probing into specific prefabricated components adopted in the samples, it is discovered that precast windows and walls are more conducive to waste minimization. This is coincident with the fact that these components are also widely adopted in the sample buildings. This study reconfirms the positive effects of prefabrication on waste minimization and articulates that two types of prefabricated components play relatively bigger role in minimizing construction waste. The strengths of this study lie in its statistical analyses of a valuable and objective quantitative dataset measuring prefabrication and waste generation rates. Future studies are recommended to prove the corollary – it is not what category of prefabricated component, but the actual proportion of prefabrication in the total construction volume that matters to waste minimization.
18. Environmental and economic assessment on 3D printed buildings with recycled concrete
With increasing attention on sustainable development, 3D printing construction and recycled concrete have drawn extensive interest as emerging construction technology and novel building materials. At this intersection, we attempted to evaluate the environmental impact and economic benefit of 3D printed buildings made of recycled concrete employing life-cycle assessment tools. Goal and scope definition, materials and scenarios, life-cycle inventory analysis, life-cycle assessment impact, and interpretation were detailed based on the characteristics of concrete 3D printing to better quantify the sustainability potential of recycled concrete used in 3D printed buildings. We found that although increases in using recycled aggregate could produce less pollutant emissions, the environmental impact caused by 3D printing concrete construction is generally larger than traditional cast-in-situ concrete construction. This is because additional cement is required in the 3D printing process to maintain dependable concrete performance. From the economic perspective, 3D printing concrete construction technology has significant advantages over traditional cast-in-situ concrete construction, saving the heavy cost of formwork and labor. Such benefit is even more pronounced in geometrically irregular buildings. We also found that the cost of buildings made of recycled concrete decreased as the proportion of recycled aggregate increased, owing to the higher price of natural aggregate. This paper contributes to identifying key factors in the life-cycle evaluation of 3D printing construction with cementitious materials.
19. Measuring the heat transfer coefficient (HTC) in buildings: A stakeholder’s survey
The heat transfer coefficient (HTC) is a very important factor influencing the energy performance of a building. Recent studies have shown the importance of on-site measurements of the HTC in reducing the performance gap in buildings. However, its measurement setup and calculation procedures are known to be intense and complex. Due to this, many stakeholders in the building industry find it impractical and insufficient for their needs. This paper presents the results of an international survey that targets such stakeholders with the aim to get their perspectives on HTC measurements on-site. Several stakeholders from 14 countries in Europe participated in the survey. The survey is categorized into four parts: a) basic data about the participants, b) their interest in methods for measured energy performance, c) their views on the characteristics of such a methodology and d) their concerns and opportunities. The results reveal that the stakeholders are highly interested in measuring the HTC on-site. The results also provide interesting insights on the aspects relevant for them and their customers. In particular, we elaborate on their perspective on the time to conduct the measurement, the cost of the setup, the measurement duration and the acceptable error. The assimilated understanding from the survey will help the building and the construction industry to identify opportunities for a progressive assessment campaign involving on-site measurements. This study is part of the International Energy Agency’s Energy in Buildings and Communities Programme (IEA EBC) Annex-71 project titled ‘Building energy performance assessment based on optimized in-situ measurements’.
20. The effect of infill walls made by eco materials on mechanical response, energy performance and CO2 print of residential and non-residential low-rise buildings
With the aim of both reducing environmental footprint and improving technological properties, several construction materials have been successfully manufactured using using waste. However, the assessment has commonly been based on comparing technological behaviors, while the overall assessment of the so made building has been commonly overlooked. Thus, this papers shows the energy and mechanical performance of buildings with same structure design, building shape and envelopes characteristics but with different types of infill walls (IWs) which have been modelled by considering traditional materials (i.e. adobe and perforated fired clay bricks) and eco-materials, such as adobe and bricks made by using up to 10% and 17.5% of biomass bottom ashes, respectively. Building models have been designed in accordance with building codes, in terms of seismic and energy savings criteria. In addition, residential (RB) and non-residential (NRB) uses have been also considered for calculations. IWs had in all cases similar equivalent thermal transmittance, achieved by varying the air gap length between layers in order to establish a common comparative framework. Otherwise, IWs showed a different thermal capacity depending on used material within the wall construction. The analysis concluded that the mechanical behavior was similar in all cases, regardless the excess of weight added by adobes. Besides, in low height buildings the increasing of stiffness possesses an advantage for lateral loads resistance. In addition, by using adobe with ashes, 5% of equivalent CO2 footprint (i.e. from cradle to gate) and 4% of energy consumption may be saved. These savings must be even lower when the entire life cycle is considered, since adobes may be easily collected and reused without any treatments while fired clay bricks require further treatments.
21. Energy-carbon-investment payback analysis of prefabricated envelope-cladding system for building energy renovation: Cases in Spain, the Netherlands, and Sweden
Buildings have become a major concern because of their high energy use and carbon emissions. Thus, a material-efficient prefabricated concrete element (PCE) system was developed to incorporate construction and demolition waste as feedstock for residential building energy renovation by over-cladding the walls of old buildings. By conducting life cycle assessment and life cycle costing using the payback approach, this study aims to explore the life cycle performance of energy conservation, carbon mitigation, and cost reduction of the PCE system in three European member states: Spain, the Netherlands, and Sweden. The results show that the energy payback periods for Spain, the Netherlands, and Sweden were 20.45 years, 17.60 years, 19.95 years, respectively, and the carbon payback periods were 23.33 years, 16.78 years, and 8.58 years, respectively. However, the financial payback periods were less likely to be achieved within the building lifetime, revealing that only the Swedish case achieved a payback period within 100 years (83.59 years). Thus, circularity solutions were considered to shorten the PCE payback periods. Using secondary materials in PCE fabrication only slightly reduced the payback period. However, reusing the PCE considerably reduced the energy and carbon payback periods to less than 6 years and 11 years, respectively in all three cases. Regarding cost, reusing the PCE shortened the Swedish payback period to 29.30 years, while the Dutch and Spanish cases achieved investment payback at 42.97 years and 85.68 years, respectively. The results can be extrapolated to support the design of sustainable building elements for energy renovation in Europe.
22. Seismic performance of a proposed wood-concrete hybrid system for high-rise buildings
A novel wood-concrete system that can be used for high-rise construction in seismically active regions is presented and analysed. The hybrid system is achieved by substituting two out of every three concrete floors and walls in a conventional coupled core wall concrete building with prefabricated light-frame wood modules. To demonstrate the system’s feasibility, a 30-story concrete building and a 30-story hybrid building are designed for the seismicity of Vancouver, Canada, according to the 2015 National Building Code of Canada. Both buildings are evaluated with nonlinear time history analyses. To accurately consider the seismic hazard contribution from the Cascadia subduction zone, a multiple event-based conditional mean spectrum record selection method is adopted to construct target spectra for each hazard source (crustal, subcrustal and subduction). The results show that the seismic mass of the proposed hybrid system is reduced when compared to the concrete building, resulting in a shorter fundamental period but also a lower seismic load demand. The nonlinear time history analyses demonstrated that the hybrid system meets the current seismic code requirements and has lower seismic demands in terms of floor displacement, inter-story drift ratio and story shear forces in both coupling and cantilever directions, demonstrating the feasibility of the proposed system for high-rise construction.
23. Life cycle assessment (LCA) of natural vs conventional building assemblies
Natural earthen and bio-based building materials are critically needed to dramatically reduce energy-intensive and extractive construction practices that are the hallmark of the modern building industry. Building assemblies such as cob, light straw clay and rammed earth were shown to provide an optimal indoor environment for occupant comfort and health. Despite these advantages, natural materials are still not widespread in mainstream construction for two primary reasons: technical data is inadequate to quantify their energy performance in different climates, and environmental measures are missing to perform decision making throughout the design process. This paper presents an environmental life cycle assessment (LCA) of natural earthen and bio-based materials compared to conventional building materials in 6 climates: hot desert, desert, semi-arid, Mediterranean, temperate, and continental. Results show that, when coupling the embodied and operational environmental impacts, the natural assemblies reduce energy demand by 32–59% in the hot desert climates, 29-55% in semi-arid climates, 46-73% in Mediterranean climates, 34-57% in temperate climates and 27-50% in continental climates as compared to conventional assemblies. The operational impacts are shown to be highly dependent on the thermal properties and climate zone, but in all cases natural assemblies outperform conventional assemblies. In particular, light straw clay and insulated rammed earth are the top performers for all 6 climates. The work presented in this paper contributes critically needed environmental quantifications to catalyze the advancement of healthier and more environmentally sound commitments to ecological construction worldwide.
24. Spatial characterization of construction material stocks: The case of the Paris region
Better knowledge of the spatial distribution of anthropogenic stocks is key for the implementation of circular economy policies. This article focuses on the case of construction materials in the Paris region in 2013. A bottom-up approach using GIS modeling is applied to estimate and locate the stocks of 27 materials and 24 building archetypes, three transport networks and six energy and water networks. The stocks of three sub-urban areas inside the region (Paris, PC and GC) and three neighborhoods representative of urban forms are compared.
The anthropogenic stocks of the Paris region amount to 204 t/capita and contain 96% of non-metallic minerals. Buildings make up 72% of the stocks. Materials located underground represent 47% of the stocks. The density of total stocks is much higher in central Paris (4.6 t/m² of the urbanized area) than in the outskirts of GC (0.7 t/m²). Higher stock density is associated with lower shares of single-family houses and networks in total stocks.
This study suggests the possibility of systematically assessing stocks of construction materials using statistical data and GIS modeling over French regions and cities. As studying stocks with a bottom-up approach is data-intensive, to provide more accurate information, the availability and quality of data are crucial.
25. Multi-participant construction waste demolition and transportation decision-making system
Construction waste management involves multiple participants and processes. Although existing research has developed a building information model (BIM) based estimation system, the challenge of selecting a transportation and demolition plan that provides overall construction waste management from the perspective of multiple participants remains, and how multiple participants can coordinate the overall process is still unclear. This paper develops a BIM and cost-optimisation-based decision-making system for construction and demolition waste (C&DW) transportation and demolition that is capable of coordinating involved C&DW participants and suggesting a cost-effective transportation and demolition plan. Firstly, we developed a transportation plan decision model based on the optimal cost principle. The model is capable of determining the optimal demolition company, transport company and disposal company through cost analysis, and a demolition plan decision model was developed based on the work efficiency analysis of the selected participants. Secondly, we developed a decision-making system that extracts material type and volume information about C&DW emissions and emission types from BIM models. Then the system provides a cost-effective transportation plan and formulates a demolition plan that can avoid the accumulation of C&DW on site based on the decision models. A case study of the system is presented, and the results show that the system can realise the information flow of all links in the construction waste management and improve the efficiency of decision-making concerning construction waste.
26. The influence of connection stiffness on the dynamic properties and seismic performance of tall cross-laminated timber buildings
It has become common practise to use Cross-laminated Timber (CLT) panels in shear wall applications in buildings around the world. Herein, the influence of the hold-downs, vertical and horizontal shear connections between the CLT panels on the period and stiffness of buildings was investigated. Two prototypes, 12-storey and 18-storey tall, of balloon-type construction were designed. To address the local seismicity of the chosen site in Vancouver, Canada, a range of crustal, subcrustal and subduction ground motions was selected for assessment as per the 2015 National Building Code of Canada. A total of 22 three-dimensional finite element building models with different combinations of connection properties were developed. Modal and time history analyses showed that the horizontal connections have the most significant impact on the overall building stiffness, resulting in up to 47% lager drifts when compared to the baseline model with an assumed rigid connection. The hold-down and vertical connection stiffnesses have lower impact on the dynamic properties and seismic performance of tall CLT buildings. The influence of connection stiffness was found to decrease with the increase of building height for this particular CLT tall building system with the connections designed as in this research.
27. The evolution and future perspectives of energy intensity in the global building sector 1971-2060
Energy efficiency plays an essential role in energy conservation and emissions mitigation efforts in the building sector. This is especially important considering that the global building stock is expected to rapidly expand in the years to come. In this study, a global-scale modeling framework is developed to analyze the evolution of building energy intensity per floor area during 1971–2014, its relationship with economic development, and its future role in energy savings across 21 world regions by 2060. Results show that, for residential buildings, while most high-income and upper-middle-income regions see decreasing energy intensities and strong decoupling from economic development, the potential for further efficiency improvement is limited in the absence of significant socioeconomic and technological shifts. Lower-middle-income regions, often overlooked in analyses, will see large potential future residential energy savings from energy intensity reductions. Harnessing this potential will include, among other policies, stricter building efficiency standards in new construction. For the commercial sector, during 1971-2014, the energy intensity was reduced by 50% in high-income regions but increased by 193% and 44% in upper-middle and lower-middle-income regions, respectively. Given the large energy intensity reduction potential and rapid floor area growth, commercial buildings are increasingly important for energy saving in the future.
28. A testing methodology for quantification of wind-driven rain intrusion for building-integrated photovoltaic systems
Wind-driven rain (WDR) exposure is a crucial impact factor to consider for building envelope components and systems. The roof being a climate screen, shields inner structures from various precipitations preventing most of the water from intruding. Although WDR exposure tests are quite common, there is a lack of studies that explore a quantification of water intrusion during such an experiment. Novel technologies such as e.g. building-integrated photovoltaic (BIPV) systems have been steadily more used as the building envelope components, and majority of BIPV systems are designed for roof integration. Such systems are mainly viewed as electricity generators, consequently, the power output and parameters that affect them are usually in focus when these systems are evaluated, whereas little information is available on the weather protection performance of BIPV systems. To address this gap, a series of experiments were conducted to improve the testing methodology of WDR exposure for BIPV systems where quantification of water intrusion was implemented. As a result, a novel framework is presented, which includes a step-by-step test methodology and a detailed description of the construction of a water collection system. Selected BIPV system for roof integration was tested according to the methodology and collected water amounts were provided. The findings in this study demonstrate that quantification of water intrusion is feasible and provides performance-based information that will help improving the design of BIPV systems as climate screens.
29. Design matters: New insights on optimizing energy consumption for residential buildings
In this paper, we construct a unique database for 1228 residential buildings in Hong Kong to investigate how the spatial features of these residential buildings affect the electricity consumption in the communal area. We choose Hong Kong for this analysis as the city owns a large number of standard-type residential buildings managed by the public institution, which could be affected strongly by environmental policies. Both the machine learning method, based on the Least Absolute Shrinkage and Selection Operator (LASSO), and econometric regressions are adopted to analyse the data. We first utilize the machine learning LASSO technique to identify the most relevant factors for the subsequent econometric analysis. Our results show that the electricity demand for relatively low consumption building types, such as Twin Tower, is 6% lower than that of the high consumption building types. Newly constructed buildings usually belong to the medium consumption types, with the estimated monthly electricity consumption per apartment in communal areas to be around 50.2 kWh on average in 2020. These findings shed light on the nexus between spatial features and energy use for complex buildings, potentially contributing to the better crafting of energy-saving policy and the improvement of residential building programmes.
VẬT LIỆU XÂY DỰNG
1. Potential use of sugar cane bagasse ash as sand replacement for durable concrete
The increasing urban development, led by concrete, requires a higher availability of materials and energy, and it will be responsible for a high waste generation. To face the exploitation of natural resources, the use of fossil fuels and the reduction of waste disposal, new environmental-friendly strategies emerge accomplishing the circular economy principles. In this research, the use of poor reactive agro-industrial ashes as sand replacement in cement-based materials is investigated. Poor reactive sugar cane bagasse ashes (fly and bottom ash -SCB FA and SCB BA, respectively) from a power plant in Dominican Republic have been used in substitution rates of 10%, 20% and 30% of weight of sand. Physico-chemical characteristics of ashes are investigated and correlated to the performance of the bio-concretes. SCB FA showed being an enhancer of durability-related properties of the concrete even with high content of silica in form of quartz, due to the capability of modifying the microstructure of the concrete and an additional binding capacity of chlorides ions. Durability-related tests (open porosity test, electrical resistivity test, capillary absorption test and chloride migration test) have been conducted at 28, 60, 90 and 240days. Direct correlations exist when compared chloride migration resistance against porosity and electrical resistivity in concretes with SCB FA, not so for capillary absorption. This demonstrates the inadequacy of establishing conclusions about durability performance of bio-concretes based on durability tests when run independently. The use of agro-industrial ashes as substitutes of natural aggregates not only reduces the consumption of natural sand but can deliver bio-concretes with potential benefits in terms of compressive strength and durability.
2. Alternative hydraulic binder development based on brick fines: Influence of particle size and substitution rate
Brick waste is produced in large quantities by the civil engineering sector without any real valorization. One way of valorizing this material consists in incorporating brick fines in cement. The substitution of clinker with this material produces an alternative hydraulic binder. In addition to the reduction in cost and energy saving, blended cement based on brick fines would present the advantage to improve the environmental impact of cement production by reducing its CO2 emission. Therefore, the aim of this paper is to study the use of bricks fines in cement, focusing more specifically on the impact of the size of their particles on fresh and hardened cement paste properties. Potential pozzolanic activity of the three brick fines was investigated as well as its influence on the microstructure and strength of cement paste samples.
The results showed that it was possible to produce blended cement based on brick fines. Substitution rates up to 20% with brick fines whose dimensions are close to those of clinker gave good performances compared to the reference cement. The brick fines clearly impact the hydration process through nucleation action and pozzolanic activity.
3. Using viscosity modifying admixture to reduce diffusion in cement-based materials: Effect of molecular mass
Construction and Building Materials, Volume 290, July 2021, 123207
The viscosity modifying admixtures (VMAs) can increase the pore solution viscosity of cement-based materials and thus slow down the diffusion of corrosive chemicals. As a key parameter, the increase of the molecular mass of VMAs can improve the anti-corrosion performance. However, if it becomes too large, the VMAs will significantly increase the bulk viscosity of the solution but do not improve the resistance to corrosive chemicals. Aiming at determining the range of molecular mass in which the resistance of cement-based materials can be optimized, the diffusion behavior of KCl in VMAs solutions with various molecular mass was explored. Then the influence of molecular mass of VMAs on chloride diffusion, mechanical properties, hydration and pore structure development of mortar were systematically investigated. The results indicated that within molecular mass range of 600-1500, VMAs can efficiently reduce the ion diffusion in cement-based materials. After 28 days of exposure, the samples containing 5% of polyethylene glycol (PEG) with the molecular mass of 1000 exhibits the minimum diffusion coefficient, which is 30.00% lower than that of the control group. The steric hindrance, which is mainly dependent on the molecular mass of the organic solute rather than its structure, directly determines the microviscosity of a solution. Although the addition of VMAs unfortunately coarsens the pore structure of mortar, and thus leads to the decrease of mortar strength, this study provides a novel approach to improve the durability of cementitious materials by optimizing the molecular mass of VMAs.
4. Bamboo fiber has engineering properties and performance suitable as reinforcement for asphalt mixture
Construction and Building Materials, Volume 290, July 2021, 123240
Bamboo is a plant species that features fast-growing characteristics, and bamboo fiber is a kind of environmentally attractive fiber, which is affordable, recyclable, degradable and renewable. This exploratory study entails laboratory tests conducted to evaluate the potential impact of bamboo fiber on the properties of asphalt mastic and mixture, in comparison to that of lignin fiber. To analyze the road performance and reinforcement mechanism of bamboo fiber asphalt mixture, three kinds of fiber asphalt mastics and mixtures, non-fiber, lignin fiber and bamboo fiber, were prepared. The thermal properties of asphalt mastic and the mechanical properties, high-temperature property, low-temperature property, moisture susceptibility and anti-aging property of asphalt mixtures were tested. Finally, the mechanism of interactions between fiber and mixture was revealed using a scanning electron microscope. Both types of plant fiber can improve the degree of crosslinking between asphalt molecules, thus slightly improving the thermal stability of asphalt mastic at high temperature and effectively decrease its temperature sensitivity. The mechanical properties of lignin fiber asphalt mixture outperformed those of bamboo fiber, while the bamboo fiber asphalt mixture exhibited excellent road performance (especially high-temperature stability, low-temperature crack resistance and moisture stability), notably better than that of lignin fiber. Bamboo fiber can form a close connection with mixture and increase the proportion of structural asphalt in the mixture through adsorption. Both adsorption and mechanical anchoring can reduce the temperature sensitivity and moisture sensitivity of the fiber-reinforced asphalt mixture. The distributed fibers can form a three-dimensional network structure in the asphalt mixture, delaying and controlling the occurrence and development of large cracks in the mixture. Bamboo fiber is a viable substitute for lignin fiber, and its beneficial effects on asphalt mixture might be enhanced in the future by further engineering its surface microstructure and chemistry and improving its dispersion.
5. A new method for anti-efflorescence of mortar by bio-mineralization
Construction and Building Materials, Volume 290, July 2021, 123261
When the bio-mineralization consumed Ca(OH)2 in cement-based materials, the CaCO3 generated in the pores would reduce the porosity of the specimen. Based on the mineralization of carbon-fixing microorganisms, this paper studied the effect of bio-mineralization on the surface efflorescence area on the mortar, and further studied the composition of efflorescence and the microstructure of the surface layer. Image processing (by OTSU), XRD (X-ray diffraction), TG (thermogravimetric), and MIP (Mercury intrusion porosimetry) were used to characterize the efflorescence area, efflorescence composition and porosity of the specimen. The results showed that bio-mineralization reduced the efflorescence area on the surface of the specimen, up to 25.6%; the efflorescence composition in the control group were mainly Na2SO4 and CaCO3, while in the mineralization group, the efflorescence substances were mainly Na2SO4; Bio-mineralization reduced the porosity and changed the pore size distribution of the surface layer of the specimen, and the large pores were transformed into small ones. This treatment for anti-efflorescence was convenient, environment friendly, potential in various practical applications, such as the anti-efflorescence of decorative mortar.
6. High temperature resistance of self compacting alkali activated slag/portland cement composite using lightweight aggregate
Construction and Building Materials, Volume 290, July 2021, 123250
Abstract:: The aim of this study was to fabricate self compacting alkali activated slag/Portland cement composite design by using of lightweight aggregate for high temperatures. Locally available pumice was used as lightweight aggregate. The four parameters considered in this study were: slag to cement ratio (GBFS:PC), water content, lightweight aggregate to normal aggregate ratio and alkali activator to binder ratio. After the tests carried out dependent on four parameters, six composite mixtures were determined for the high temperature experiment. For this purpose, the composite samples were exposed to temperatures of 200, 400, 600, 800 and 1000 °C and changes in compressive strength and ultrasonic pulse velocity were measured. The microstructural changes caused by the high temperatures were investigated by means of SEM and FTIR spectroscopy. Following the high temperature tests, compressive strength began to decrease with the temperature increasing. The minimum compressive strengths were observed at the temperature of 800 °C. At 1000 °C no further deterioration was observed in the compressive strength of the both PC-free and PC substituted composite mixtures. The temperatures at which the microcracks became more evident were 600 °C and 800 °C for the mixtures with 100% and 85% GBFS, respectively.
7. Evaluation of self-healing performance of a smart composite material (SMA-ECC)
Construction and Building Materials, Volume 290, July 2021, 123216
The durability of cementitious materials is affected by the presence of cracks. This paper proposed a novel composite material and evaluated its crack healing ability. This material consisted with engineered cementitious composite (ECC) and shape memory alloy (SMA) fibers. A total of 12 specimens were made and tested under flexural loads. Test parameters included material type and target displacement level. Test results indicated that specimens with SMA-ECC had great increase in strength and ductility compared with specimens with concrete. Specimens with SMA-ECC exhibited promising crack healing ability by effectively reducing the crack number and width. The self-healing ability reduced with increasing target displacement level. The self-healing ability was further investigated through ultrasonic pulse test. Ultrasonic pulse test results were consistent with the mechanical test results, indicating effectiveness of this test method. This composite material SMA-ECC has promising application in infrastructure critical for security to mitigate damage and heal cracks, and increases durability of the structure, and reduces maintenance cost.
8. Synergistic catalytic flame retardant effect of zirconium phosphate on the poplar plywood, Volume 290, July 2021, 123208
The layered two dimensional material α-Zirconium Phosphate (α-ZrP) was used to explore its effect on the flame-retardant properties of plywood in this paper. First, the positively charged polyelectrolyte polyethyleneimine (PEI) and the negatively charged polyelectrolyte ammonium polyphosphate (APP) were adsorbed to the surface of poplar veneers through layer-by-layer (LBL) self-assembly technology, then the flame-retardant modified veneer was prepared for use. Followed by, urea formaldehyde (UF) resin composite adhesives with 9%, 15% and 24% mass fractions of α-ZrP were made. The flame-retardant plywood was prepared by modified veneers and composite adhesives. The chemical composition and combustion status of modified veneers were characterized using multiple techniques, including scanning electron microscope (SEM), energy dispersive spectrometer (EDS), attenuated total reflection infrared spectroscopy (ATR-FTIR) and veneer burning experiments. Through the rheological properties and bonding quality test, the appropriate addition amount of α-ZrP was determined to be 15%. The flame retardancy of modified plywood was assessed by the cone calorimeter (CONE). The results showed that the plywood with only UF composite adhesives and the plywood with only flame-retardant veneers have limited ability to inhibit heat release. When flame-retardant veneers were used in conjunction with composite adhesives, the peak Heat Release Rate (pHRR) and Total Heat Release (THR) of the plywood were reduced by 41.8% and 22.9%, respectively, and the ability to suppress heat was significantly improved. In addition, with the introduction of α-ZrP, the total smoke production and the concentration of toxic gas CO were significantly reduced. This showed that when α-ZrP was used in conjunction with APP, α-ZrP has excellent synergistic flame-retardant property on poplar plywood. The research results provide a strong basis for the application of α-ZrP in flame retardancy of the wood based composites.
9. Durability assessment and microstructural analysis of 3D printed concrete exposed to sulfuric acid environments
Construction and Building Materials, Volume 290, July 2021, 123220
Additive manufacturing techniques are being more adopted in the construction field, and they are rapidly developing. However, it is expected that layers superposition imposes several limitations on the performance of 3D printed structures. In this regard, an efficient concrete structure should not only present reliable mechanical performances, but also appropriate durability performance against weathering. This paper presents an experimental study aiming to compare 3D printed elements to casted ones on a macro and micro scale, as well as their resistance against sulfuric acid attacks. Herein, three different mortar mixes having different thixotropic properties were used, and two solution concentrations were employed, one containing 1% sulfuric acid and the other containing 3%. At first, a visual observation of the degraded samples and their mass loss were held. Then, a microstructural characterization was performed through mercury intrusion porosemetry (MIP) and scanning electron microscopy (SEM) analyses. Still, not any printed element has cracked at the inter-layer level. Moreover, on a microscopic level, the MIP results showed that all samples of different compositions have an equal total porosity. However, the pore size distribution and their morphology largely differs between printed and non-printed specimens. The pore sizes are more spread in printed specimens. As for the SEM results, it can be clearly seen that no interface have revealed the formation of a weak plane that might even threaten the durability of the printed elements. Yet, a strong link between superposed layers has been developed, even when using materials having different rheological properties; and the overall specimen acted as a monolithic body without showing any signs of discontinuity or superposition effects.
10. Application of asphaltenes in high modulus asphalt concrete
Construction and Building Materials, Volume 290, July 2021, 123200
The current study investigates the application of asphalt binders from different sources modified with asphaltenes in high modulus base courses (HMAC). For this purpose, one crude oil asphalt binder and four asphalt binders derived from various sources of Alberta oilsands were studied. Witczak regression model was used to determine the minimum performance grade to meet the dynamic modulus requirement for HMAC. Asphaltenes were added in different quantities for modification of the asphalt binders. The effect of asphaltenes modification on the viscosity of the binders was studied using a rotational viscometer. Also, the chemical composition of the asphaltenes-modified binders was determined by SARA analysis. The results of the rheological analysis indicated that asphaltenes effect on binders performance at high temperatures was more than its negative impact at low temperatures. Furthermore, it was determined that binders from the Alberta oilsands modified with asphaltenes could achieve the performance grade requirements for HMAC applications.
11. Effect of micro-sized silica aerogel on the properties of lightweight cement composite
Construction and Building Materials, Volume 290, July 2021, 123229
Lightweight cement composite (LCC) has gained more interest and is increasingly explored by researchers due to its many advantageous properties. Silica aerogel (SA), a synthetic ultralight material, has a nano-porous structure, making it a potential option to be incorporated for LCC. Thus, this research intends to assess the influence of micro-sized SA fines on the properties of cement composite. Specifically, its effect on fresh state properties, porosity, density, compressive strength, rate of water absorption, total water absorption, wettability, and softening coefficient was investigated. The lightweight and micro-size of SA reduced the consistency and slump (up to 90%) of the fresh LCC. Besides that, its hydrophobic nature produced macropores which doubled the porosity in the cement composite. This resulted decrease in density (up to 35%), compressive strength (up to 76%), wettability (up to 21%), and softening coefficient (up to 33%). Water transport properties such as water absorption and rate of water absorption were also increased due to the formation of macropores in the SA cement composite. However, compared to some other LCCs, the cement composite produced with the SA fines in this study in overall exhibited good specific strength.
12. Observation of the microstructure and shape of self-healing microvascular in asphalt
Construction and Building Materials, Volume 290, July 2021, 123259
Microvascular containing rejuvenator is a promising smart material for self-healing asphalt of pavement. The objective of this work was to experimentallyobserve the shape and state of self-healing microvascular in asphalt. Polyvinylidene fluoride (PVDF) microvascular containing oily rejuvenator was spun through single-wet-spinning method. Thermogravimetry analysis (TGA) and scan electron microscopy (SEM) morphology results proved that microvascular can endure 300 °C high temperature in asphalt and maintain its own stability. At the same time, the microvascular can withstand drastic temperature changes while still maintaining its integrity. Micro-XCT image indicated no debonding phenomenon was found between the microvascular and bituminous binder. Oily rejuvenator can be safely stored in the microvascular without being affected. At the same time, 3D micro-XCT image showed that the microvascular did not have any entanglement or breakage even under the extrusion of the aggregates. Microvasculars were randomly distributed isotropically in the asphalt. By comparing the shape of long microvascular and short microvascular in asphalt, it is found that short one is more suitable for asphalt. Possible shapes were observed through micro-XCT slides named as C-shape, L-shape, O-shape, S-shape, and V-shape. Microvasculars were squeezed by the aggregate in the asphalt, which deformed and became deflated. However, microvascular remained intact and no breakage occurs. Oily rejuvenator was safely protected in the microvascular. The above intuitive image data are evidence proving that the microvascular containing rejuvenator will be a feasible approach to realize the self-healing and self-rejuvenating process of asphalt.
13. The effect of using nano rice husk ash of different burning degrees on ultra-high-performance concrete properties
Construction and Building Materials, Volume 290, July 2021, 123279
This work aims to highlight the effect of seven different types of nano rice husk ash (NRHA) on the mechanical, ultrasonic pulse velocity, and durability of ultra-high-performance concrete (UHPC), whereby two different scenarios were applied. Rice husk ash (RHA) was manufactured by calcining rice husk at temperatures of 300, 500, 700 and 900 °C at a constant time of burning (for 3 h). Then, it was kept for cooling with a constant rate of 100/min and different burning hours of (9, 7, 5, and 3 h, respectively). After that, the product was milled to nano size. The final nano-sized product was added by different dosages (1-5%) with a 2% step to the UHPC mixture. Compressive, splitting tensile, and flexural strength were measured accordingly. Permeability was assessed by the sorptivity test; the ultrasonic pulse velocity test was also conducted. The results showed that the addition of NRHA enhanced the compressive strength and impermeability of UHPC due to the refined pore structure. For a constant burning duration, a significant improvement in compressive strength was observed at a burning temperature of 900 °C and 700 °C for 1% NRHA and at 500 °C and 300 °C for 3% and 5% NRHA. However, for a different burning duration, a significant improvement in compressive strength was recorded at a burning temperature of 700 °C and 500 °C for 3% NRHA, which was burnt for 5 h and 300 °C for 5% NRHA, which was burnt for 9 h. Sorptivity and ultra-sonic pulse velocity confirmed the results. Therefore, the advisable condition is burning at 700 °C for 5 h for more amorphous silica with medium energy compared to other mixes.
14. Utilization of low-alkalinity binders in cemented paste backfill from sulphide-rich mine tailings
Construction and Building Materials, Volume 290, July 2021, 123221
In this study, the basic properties of waste gypsum (WG), WG and reactive MgO-activated slag (MAS-WG) binders were experimentally explored. The effects of WG content in MAS-WG binders on the unconfined compressive strength (UCS) development of cemented paste backfill (CPB) from sulphide-rich mine tailings were investigated as well. The corresponding stabilization mechanisms were assessed through mineralogical and micro-structure analysis and leaching tests. The results showed that when the content of citric acid exceeded 0.15 wt% of WG content, the initial setting time and 28 d UCS of the WG plaster of 180 mm slump were over 1 h and 15.5 MPa, respectively. The appropriate WG incorporation improved the particle gradation of MAS-WG and MAS-WG-CPB mixtures. The main hydration products of MAS-WG plaster and MAS-WG-CPB from sulphide-rich tailings were crystalline CaSO4·2H2O, ettringite (AFt) and amorphous hydrated products (C-S-H/M-S-H). The proper WG incorporation in the MAS-WG binder also significantly enhanced the early age (14 d and 28 d) UCSs of MAS-WG plaster and MAS-WG-CPB, in which the reason is that appropriate WG incorporation accelerated the hydration process of GGBS in the alkaline solution by forming ettringite (AFt) and enhanced amorphous phase development resulting in the denser microstructure. A lot of WG incorporation made the 28 d UCSs of MAS-WG-CPB decrease due to the loose micro-structure resulted from the decrease of amorphous hydration products. However, the long-stage UCSs of MAS-WG-CPB after 120 d of curing were all stable (i.e., no strength loss) regardless of WG incorporation content, which were attributed to the low-alkalinity solution in MAS-WG-CPB preventing the secondary expansive hydration product formation. The long-stage (180 d) UCS of MAS-WG-CPB had positive correlations with the refined pore structure and the alkalinity of the leaching solution.
15. Enhancement effect of the aggregate particles on the low-temperature cracking resistance of the asphalt mortar
Construction and Building Materials, Volume 290, July 2021, 123225
On the mesoscale, the aggregate which is a particle-reinforced material, plays an important role in improving the mechanical properties of the pavement material. To study the enhancement effect of the aggregate particles on the low-temperature crack resistance of the asphalt mortar, the asphalt mortar specimens using the aggregate with different particle sizes were formed by applying the static pressure. The indirect tensile test (IDT) was carried out to analyze the enhancement effect of the aggregate particles. Also, the pre-cracked asphalt mortar specimens prepared by the waterjet cutting technology were used for IDT. IDT was combined with the extended finite element method (XFEM) to analyze the influence of the initial configuration of the crack on the enhancement effect of the aggregate particles against the low-temperature cracking resistance and the configuration resultant force at the crack tip. It was observed that, under the low-temperature, the aggregate with different particle sizes could suppress the initiation of cracks in the asphalt mortar with different degrees. As a result, an increase in the low-temperature cracking resistance of the asphalt mortar depended on the particle size of the aggregate. The low-temperature cracking resistance of the asphalt mortar significantly decreased with an increase in the initial crack length. The aggregate could suppress such adverse effect of the initial crack length on the low-temperature cracking resistance of the asphalt mortar to a certain extent. On the other hand, as the initial deflection angle of the crack increased, the enhancement effect of the aggregate on the low-temperature cracking resistance of the asphalt mortar gradually weakened. But when the initial deflection angle was larger than 45°, this weakening trend was mitigated due to the ‘crack shielding effect’ among branch cracks.
16. Internet of Things (IoT) for masonry structural health monitoring (SHM): Overview and examples of innovative systems
Construction and Building Materials, Volume 290, July 2021, 123092
The main aim of using the IoT paradigm is related to the possibility of a connectivity extension of several common SHM devices by means of Internet. The connected devices are thus able to transmit and process data, guaranteeing new scenarios in the design of acquisition systems in different fields of science and engineering. The innovations have led the researchers to extend the application of the IoT paradigm to the SHM of masonry structures making sure that the experiments conducted in this framework are able to ensure good results with promising future improvements. The main uses, to date, have been implemented, for example, to monitor individual structural elements, reducing the risks for users due to partial or total collapses of the structure, or for the identification, detection and characterization of damage and degradation of construction materials. The aim of this work is to expose a general overview of the SHM systems used by the authors for masonry structures belonging to historical and cultural heritage, arguing their use for the protection from earthquakes with related advantages. This will be shown thanks to two preliminary SHM systems designed and implemented by the authors on two case studies using IoT, described in the paper with their related cyber and physical parts.
17. Mechanical and physical performance of natural hydraulic lime mortars
Construction and Building Materials, Volume 290, July 2021, 123272
Natural hydraulic lime (NHL) is a material which has received increased interest in the past decade as a binder for the production of mortars. The renewed interest of researchers and builders in natural hydraulic lime is attributed to its enhanced compatibility with many traditional materials, as well as the fact that it is an environmentally friendly material, especially in relation to modern cement. In the present study, two different types of natural hydraulic lime mortars are studied, using NHL2 and NHL3.5 as binder (in accordance to the new classification EN 459-1:2010) and the same river sand, while the influence of different binder to aggregate ratios on mortar characteristics is also investigated. Fresh mortar characteristics are examined immediately after mixing, while hardened mortar characteristics are evaluated at different mortar ages. Specifically, the mechanical performance of the mortars is evaluated through flexural and compressive strength tests, as well as the dynamic modulus of elasticity, which is estimated through ultrasound pulse velocity measurements. Physical performance of the mortars is investigated through the examination of the pore network structure characteristics, via mercury intrusion porosimetry measurements, and through the examination of hygric characteristics, via water absorption tests. The binder to aggregate ratio seems to play an important role in the development of the mechanical and physical characteristics of the mortars, while it influences mortar properties differently according to the type of the binder.
18. Recycling the waste dolomite powder with excellent consolidation properties: Sample synthesis, mechanical evaluation, and consolidation mechanism analysis
Construction and Building Materials, Volume 290, July 2021, 23198
Alkali activation has gradually become an important means to treat solid waste and produce green cementitious materials. The alkali-activated samples were successfully prepared by waste dolomite powder, whose consolidated-performance and environmental friendliness are both excellent. This work intensively investigates the preparation process and thermo-mechanical properties of alkali-activated waste dolomite powder, and emphatically analyses the consolidation mechanism, which is distinct from that of silicate alkali-activated materials. The optimal preparation parameters were found as follows: alkali concentration (1.5 wt%), compression molding pressure (125 MPa), curing temperature (could be from 22 to 150 °C), and holding time (2 h); under these preparation parameters, the corresponding samples’ compressive strength could reach a level between 67.77 MPa and 73.75 MPa. And its heat-resistance temperature is at least 400 °C, which is higher than that of Ordinary Portland Cement. Via the characterization analysis including TG-DTA, FTIR, XRD, SEM, and EDS, two-part mechanisms were suggested that may support this performance: the consolidation mechanism at room temperature (22 °C) was considered to involve two kinds of chemical reactions that were dedolomitization and ion cross-linking, and the thermal reaction was believed to contain the decomposition of magnesite and then of calcite. These results exhibit the alkali-activated waste dolomite powder has excellent mechanical properties and heat-resistance temperature, which not only provides an efficient, green path for waste dolomite powder handing but also renders a novel idea in the alkali-activated system based on dolomite.
19. Preparation and performances of foamed hydraulic lime
Construction and Building Materials, Volume 290, July 2021, 123244
Hardened hydraulic lime with proper strength, high porosity and large carbonation capacity is considered to be an ideal candidate for CO2 adsorption and in-situ solidification. In this study, hydraulic lime (HL) was obtained by mixing of hydrated lime (Ca(OH)2, CH) and white Portland cement (WPC). Foamed HLs with dry bulk densities of 300 kg/m3 and 600 kg/m3 were prepared in order to increase the CO2 permeability in hardened matrix. Then, CO2 was rapidly captured by foamed HLs to form CaCO3 due to the air-hardening reaction. Results indicated that the CO2 captured capacity and the thermal insulation performance of foamed HLs was increased, but the compressive strength was reduced with the increase of CH in HLs. Carbonation rate was further accelerated under accelerating carbonation condition. Pore size of foamed HLs was refined with the cement hydration and carbonation process, which was beneficial to the increase of compressive strength and thermal insulation performance of foamed HLs. It is expected that foamed HLs could be used as building insulation materials with superior capacity and rate for CO2 adsorption and solidification.
20. Thermal and mechanical performance of cool concrete pavements containing waste glass
Construction and Building Materials, Volume 290, July 2021, 123238
Elevated pavement temperature leads to urban heat island (UHI) and thermal distress in pavements. Moreover, the disposal of non-biodegradable waste materials such as glass is a major research problem and a serious environmental threat. Contrasting to most of the past studies that mainly concentrate on the mechanical properties of concrete containing glass aggregates, the current study evaluates their thermal properties. The key aim of this study is to assess the possibility of developing cool pavements by incorporating waste glass. Utilizing these waste materials for constructing road pavements, without compromising desired structural properties, is the best possible method for disposing them. Further, the incorporation of lighter colored glass particles in concrete reduces the pavement temperature. Glass was added as a partial replacement to fine aggregates, and zeolite was added as supplementary cementitious material to minimize the alkali-silica-reaction (ASR) expansion. The result of the study indicates that there is no significant reduction in mechanical strength up to 10% replacement dosage of fine aggregates with glass. Moreover, with 10% replacement of fine aggregate with glass and cement with zeolite respectively, the pavement was found to be 7.9 ℃ cooler than that of the control mix. Furthermore, for this replacement dosage, a reduction up to 75.15% in the maximum warping stresses was reported with respect to the control mix.
21. Characterization of a novel bio-insulation material for multilayer wall and research on hysteresis effect
Construction and Building Materials, Volume 290, July 2021, 123162
In this work, the hygrothermal properties of a novel bio-insulation material made of magnesium phosphate cement (MPC) and corn stalk (CS) were measured and compared with three excellent materials (date palm concrete, hemp-lime concrete and rape straw concrete) from previous study. To analyze the hygrothermal behavior of MPC-CS as the exterior insulation layer of multi-layer wall. The numerical model for multilayer walls with different bio-insulation layers was established to study the coupled heat and moisture transfer under real summer and winter climatic conditions. Furthermore, the effect of hysteresis on the hygrothermal behavior of external insulation multilayer walls was investigated. The results showed that multilayer wall containing MPC-CS insulation layer can better regulate temperature (T) and relative humidity (RH) variations, especially during the wintertime. When the hysteresis effect is taken into account, the accuracy of calculation will be improved. For highly dependent materials, it is necessary to calibrate the sorption isotherms to obtain more accurate results. However, as the depth of multilayer wall increased, the influence of hysteresis gradually decreased.