Công bố quốc tế trong lĩnh vực kiến trúc, xây dựng (Tuần 3 tháng 8 năm 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:
– Mối liên hệ giữa các chỉ số sinh thái cảnh quan với dữ liệu khảo sát công khai về chất lượng cảnh quan được cảm nhận và sự gắn bó với địa điểm của người dân.
– Tái tích hợp sinh thái vào các phương pháp tiếp cận cảnh quan tổng hợp.
– Quản lý cảnh quan: tiềm năng và thách thức của các phương pháp tiếp cận tổng hợp đối với tính bền vững ở Indonesia.
– Tái tạo thành phố: Các yếu tố góp phần nâng cấp các sân trường xanh ở Amsterdam và The Hague.
– Đóng góp của vườn cho con người và không gian xanh đô thị.
– Đánh giá mức độ dễ bị tổn thương của không gian xanh đô thị đối với bão ở Đài Loan.
– Tác động của các chiến lược thiết kế bãi đậu xe và phủ xanh đến điều kiện nhiệt độ ngoài trời vào mùa hè trong các khu dân cư cũ trung tầng.
– Bảo vệ các không gian mở ven đô ở cấp độ hoạch định chính sách khu vực: Ví dụ từ sáu khu vực châu Âu.
– Tìm hiểu các động lực vĩ mô, vi mô của mật độ đô thị: Một nghiên cứu điển hình về các thành phố Ấn Độ có quy mô khác nhau.
– Các lợi ích kinh tế và sinh thái của việc tiết kiệm các hệ sinh thái để bảo vệ các dịch vụ đô thị.
– Đánh giá xây dựng mô hình thông tin và tích hợp Internet of Things cho môi trường thông minh và bền vững.
Khoa học và công nghệ trong lĩnh vực kiến trúc, xây dựng:
– Khung hệ thống kiểm tra 3D trực quan giám sát và phân tích tình trạng kết cấu.
– Phân tích Bibliometric của Mô hình xây dựng thông tin, Hệ thống Thông tin Địa lý và Tích hợp môi trường Web.
– Tự động nhận dạng mô hình vết nứt từ hình ảnh để đánh giá tình trạng của kết cấu bê tông.
– Giám sát và phân tích an toàn nhanh chóng việc xây dựng hố móng bằng hình ảnh máy bay không người lái.
– Các biến dạng ở kích thước Centimet của môi trường xây dựng được khám phá bằng phép đo quang dựa trên máy bay không người lái.
– Tiếp cận Deep learning để phát hiện và phân loại nhanh các hư hỏng cụ thể.
– Phân bổ công suất bằng bộ tổng hợp phụ tải với các phụ tải không đồng nhất sử dụng phép chiếu có trọng số.
– Thiết kế chung và tối ưu hóa hiệu suất của các tòa nhà dân cư dựa trên thuật toán tham số.
– Xác định khả năng lắp đặt dựa trên phân tích vòng đời sinh thái của các hệ thống cung cấp năng lượng của tòa nhà.
– Đóng góp của sự phân tán vào sự cân bằng năng lượng của mái một tòa nhà
Vật liệu xây dựng:
– Tăng cường ưu điểm của geopolyme tro bay hàm lượng canxi cao chứa hàn the với tro trấu.
– Tái chế chất thải trấu để làm bê tông bền vững: những đánh giá quan trọng
– Đánh giá hiệu quả quản lý chất thải xây dựng và phá dỡ thông qua hệ thống phân cấp quản lý chất thải; một trường hợp của các công ty xây dựng lớn của Úc.
– Đồng bám và cố định trong quá trình thủy hóa xi măng trong hỗn hợp bê tông có chứa quặng đuôi đồng.
– Phát triển bê tông hiệu suất cực cao thân thiện với môi trường dựa trên bột bazan phế thải cho Đường sắt Tứ Xuyên-Tây Tạng
– Lợi ích của cơ chế đồng gia công khu vực: Trường hợp của ngành thép / gang và xi măng ở Việt Nam, Lào và Campuchia
– Tương tác của biopolymer với vật liệu địa phân tán và đặc tính của nó: Một cách tiếp cận thân thiện với môi trường để kiểm soát xói mòn
– Chuẩn bị và mô tả đặc tính của vật liệu tổng hợp gốc xi măng cường độ siêu cao và siêu dẻo kết hợp bột gạch đất sét thải
– Sử dụng CO2 trong quá trình cacbonat hóa nước trực tiếp của bê tông được tạo ra từ quá trình tái chế cốt liệu: Ảnh hưởng của tỷ lệ rắn – lỏng và nồng độ CO2
– Các cách tiếp cận để đạt được tính lưu động trong xi măng trộn đất sét nung cacbon thấp
Xin trân trọng giới thiệu!
QUY HOẠCH ĐÔ THỊ
- Relating landscape ecological metrics with public survey data on perceived landscape quality and place attachment
Landscape Ecology volume 36, pages2367–2393 (2021)
It is essential for policy-making and planning that we understand landscapes not only in terms of landscape ecological patterns, but also in terms of their contribution to people’s quality of life.
In this study our objective is to test relationships between landscape ecology and social science indicators, by investigating how landscape patterns are linked to people’s perception of landscape quality.
To assess public views on landscapes we conducted a survey among 858 respondents in Switzerland. We combined this survey data on perceived landscape quality and place attachment with landscape metrics (e.g. diversity, naturalness of land cover, urban sprawl, fragmentation) in a statistical model to test hypotheses about the relationships between the different variables of interest.
Our results illustrate the contribution of both landscape composition metrics and social science indicators to understanding variation in people’s perception and assessment of landscape. For example, we found the landscape ecology metrics on urban sprawl and fragmentation to be a negative predictor of overall satisfaction with landscape, and that perceived landscape quality positively predicted place attachment and satisfaction with the municipality landscape.
This study highlights the importance and feasibility of combining landscape ecology metrics and public survey data on how people perceive, value and relate to landscape in an integrated manner. Our approach has the potential for implementation across a variety of settings and can contribute to holistic and integrated landscape assessments that combine ecological and socio-cultural aspects.
- Re-integrating ecology into integrated landscape approaches
Landscape Ecology volume 36, pages2395–2407 (2021)
Integrated landscape approaches (ILAs) that aim to balance conservation and development targets are increasingly promoted through science, policy, and the donor community. Advocates suggest that ILAs are viable implementing pathways for addressing global challenges such as biodiversity loss, poverty alleviation, and climate change mitigation and adaptation. However, we argue that recent advances in ILA research and discourse have tended to emphasize the social and governance dimensions, while overlooking ecological factors and inadequately considering potential trade-offs between the two fields.
By raising the issue of inadequate integration of ecology in ILAs and providing some general design suggestions, we aim to support and incentivise better design and practice of ILAs, supplementing existing design principles.
In this perspective we draw on the recent literature and our collective experience to highlight the need, and the means, to re-integrate ecology into landscape approaches.
We suggest that better incorporation of the ecological dimension requires the integration of two approaches: one focusing on conventional scientific studies of biodiversity and biophysical parameters; and the other focusing on the engagement of relevant stakeholders using various participatory methods. We provide some general guidelines for how these approaches can be incorporated within ILA design and implementation.
Re-integrating ecology into ILAs will not only improve ecological understanding (and related objectives, plans and monitoring), but will also generate insights into local and traditional knowledge, encourage transdisciplinary enquiry and reveal important conservation-development trade-offs and synergies.
- Governing the landscape: potential and challenges of integrated approaches to landscape sustainability in Indonesia
Landscape Ecology volume 36, pages 2409–2426 (2021)
In recent years, landscape sustainability, the maintenance and improvement of biodiversity, ecosystem services, and human well-being in landscapes, has become a core objective of conservation initiatives. Yet efforts to promote sustainability often conflict with other landscape objectives. Globally, integrated landscape approaches have emerged as desirable processes for reconciling these conflicts. Integrated landscape approaches seek to foster improvements in landscape-scale governance to meet sustainability objectives.
As scientific and political support for these new landscape approaches continues to advance internationally, there is a need to learn from the processes, constraints, and opportunities. We seek to enrich understandings of landscape approaches and their contributions to governance and sustainability through conserving biodiversity and maintaining ecosystem services.
Focusing on eight case studies at different stages of development in Indonesia, we explore how practitioners influence landscape sustainability through integrated approaches. We used questionnaires and literature to collect information on objectives, attributes and challenges of landscapes approaches.
We find landscape approaches in Indonesia closely reflect guidance principles. Emerging lessons from landscapes include adapting strategies to local priorities for inclusive problem-framing and engaging in nested learning systems. Aligning landscape actions with policy for coherent governance across scales remains a key challenge.
Creating and maintaining governance that supports landscape sustainability is a core principle of landscape approaches. Establishing institutional arrangements for landscape sustainability will require working across legislative and political boundaries for coordinated action. We highlight the need to document and measure impact, and the potential for future learning from landscape sustainability science.
- Renaturing the city: Factors contributing to upscaling green schoolyards in Amsterdam and The Hague
Urban Forestry & Urban Greening, Volume 63, August 2021, 127190
To increase urban climate resilience, the renaturing of cities plays an important role. One strategy is the greening of schoolyards to increase climate resilience and bring additional benefits such as nature education and a healthy environment. While these are small projects, they could make a significant impact if they can be upscaled. With the intent of identifying the local barriers to the upscaling of green schoolyards, this research applies an upscaling framework to analyze and compare two initiatives that incentivize the greening of schoolyards by providing funds to local schools in Amsterdam and The Hague. There is not one barrier but a combination that seems to prevent upscaling, so it is a combination of factors that prevents the successful up-taking of green schoolyards: lack of environmental awareness, difficulties in acquiring monetary funds, lack of time and expertise from the demand-side, complexity of the bureaucratic processes, and lack of political will.
- Gardens’ contribution to people and urban green space
Urban Forestry & Urban Greening, Volume 63, August 2021, 127198
Cities are experiencing numerous challenges, adversely affecting human health and wellbeing. Urban green space provides ecosystem services that are important to meet urban challenges. One type of urban green space is private gardens (yards) that make up an essential part of many urban areas. Gardens can support urban biodiversity and provide cultural ecosystem services (CES) to its owner. However, the provision of garden benefits depends on garden size, design and management. This study aims to explore private gardens contribution to urban biodiversity and garden owners’ wellbeing (in terms of CES), and to understand the influence of urban planning and garden design and management. We use a conceptual framework to illustrate complexities and interlinkages: the garden ‘human-nature’ nexus. The study is based on a garden land-use inventory and interviews with 35 garden owners in Lund, Sweden. Results show that urban development influence garden’s biodiversity potential by limiting available space or garden vegetation. New properties were mainly covered by buildings and paved surfaces and their small gardens contained few biodiversity features and large trees. Garden owners used multiple information channels to gain inspiration and knowledge, and aesthetic and edibility are important plant qualities governing garden plant choice. Many garden owners experienced gardens problems that influence design and management. The most important garden CES were social bonds, recreation, nature experiences and relaxation. Age and gender influence both garden CES and garden design and management. We conclude that private gardens have a potential to function as multifunctional spaces, but to harness their full potential there is a need to transform how we plan, develop, manage and not at least recognize private green space. We argue that the garden ‘human-nature’ nexus can help to illustrate the important interlinkages existing between e.g. urban planning, biodiversity and garden ES, and to foster sustainable urban green space governance.
- Evaluation of urban greenspace vulnerability to typhoon in Taiwan
Urban Forestry & Urban Greening, Volume 63, August 2021, 127191
Urban greenspace (UGS) represents an essential component of city ecosystems. It plays a critical role for various purposes, such as reducing urban heat island effect and air pollution, regulating torrential run-off and offering joyful routes for walking, jogging and cycling based on personal interest as well as a platform for social networking. It is especially important in a populated country like Taiwan with population highly concentrated in cities. It is rather vulnerable to strong winds and heavy precipitation brought up by typhoons, while there are no existing frameworks to access its vulnerability to typhoons in Taiwan. Here, we examine the vulnerability of UGS to typhoons in Taiwan by a novel assessment framework considering 21 indicators organized into three dimensions, including hazard, exposure/sensitivity and adaptive capacity. The 21 indicators are derived from the Sentinel-2 MSI data obtained from European Space Agency (ESA), typhoon data acquired from Japan Meteorology Agency (JMA), and census data achieved by the government official sites of Taiwan. Google Earth Engine and GIS are used to analyze the deviation of UGS variables. Five major metropolitan areas of Taiwan are selected as the study sites, consisting of Taipei, New Taipei, Taoyuan, Taichung, and Kaohsiung cities. Interestingly, it is found that (i) There exists a great spatial gap between hazard levels and the top-priority regions to enhance the strategies and adaptive capacity in order to better respond to typhoons in Taiwan; (ii) The Northern and middle parts of Taiwan exhibit high and very high hazard levels since the occurrence frequency and wind speed of typhoons are higher. In contrast, the Southern Taiwan is characterized by low and very low hazard levels occupying over approximately half of the study sites; (iii) Exposure and sensitivity of the UGS in Taiwan vary greatly from very low to very high levels over the study sites with 43 % attributed to high and very high levels; and (iv) 22 % of the metropolitan areas are classified as high and very high vulnerable, mainly distributed over the Taoyuan, Taichung, Taipei, and New Taipei cities. Results suggest that the presented framework is useful in evaluating the vulnerability of UGS to typhoons and implicates proper management of urban trees as a nature-based solution to mitigate the impacts of climate change.
- Green wall plant tolerance to ambient urban air pollution
Urban Forestry & Urban Greening, Volume 63, August 2021, 127201
Air pollution exposure can impact plant physiology, morphology and biochemistry, leading to dramatic alterations to plant systems, function and growth. The use of plants for air pollution mitigation is increasing in popularity, particularly in the form of green wall systems, making the identification and classification of pollution sensitive and tolerant species essential. This study aimed to examine the health of common green wall species exposed to ambient air pollution in situ, and thus to identify tolerant species for use in high pollution environments. To do this, 11 plant species were sampled across 15 outdoor green walls, over a 6 month period, and tested for leaf chlorophyll, pH, relative water content and carbon content. Control glasshouse samples were collected simultaneously. Linear mixed models were used to examine patterns in plant health traits across species. Significant differences in plant health between control and in situ samples were observed, however, plant species were not consistent in their responses across health variables. As such, there no clear distinction of the most tolerant species could be made. As most species showed no significant health differences from pollution exposure, it is reasonable to conclude that all test species were able to withstand pollution exposure at the trial sites without any adverse effects.
- Impact of parking and greening design strategies on summertime outdoor thermal condition in old mid-rise residential estates
Urban Forestry & Urban Greening, Volume 63, August 2021, 127200
Old residential estates account for over 40 % of the total residential development in 20 major cities in China while the percentage is up to 61 % for Shanghai. Many of these old residential estates are facing the dilemma of the increasing demand for car parking space and the deteriorating outdoor thermal conditions. This paper presents a parametric study on the impact of arranging parking spaces and greening on summertime outdoor thermal conditions (air temperature and physiological equivalent temperature) considering the land and building constraints of old residential estates. Field measurements were conducted in an old residential estate located in the inner-city area of Shanghai to obtain the status-quo parking and greening design and basic thermal condition. The current situation along with 26 practical scenarios with different parking areas and greening designs were simulated using the validated ENVI-met model. Results confirm that adding parking space increases thermal stress and its impact is strongly affected by greening design. The magnitude of temperature reduction caused by the greenery decreases as the parking spaces increase, while multifunctional solutions with parking under large trees have strong potential in improving thermal comfort. Regression was also conducted to quantify the impact of different greenery (large trees, medium trees, small trees, shrubs, and grasses) on the thermal condition.
- Effectiveness of urban green space on undergraduates’ stress relief in tropical city: A field experiment in Kuala Lumpur
Urban Forestry & Urban Greening, Volume 63, August 2021, 127236
This research examined the psychological (perceived restoratives, emotion, stress, and mood) and physiological (blood pressure readings) effects of short-range visits to urban environments. Ninety participants visited two urban areas; Bukit Jalil Urban Park (a green space) and Bukit Jalil Urban Street (an urban a built-up city centre as a controlled environment) located in a tropical city Kuala Lumpur. Participants took a 20-minute leisure walk along the given routes in both the study areas. The findings indicate that the urban park has had an overall rehabilitative impact in contrast to the built-up environment. Overall, the positive emotion has increased, and mood disturbance has decreased in the metropolitan green area after the field experiment. The findings demonstrate that even short-term visits to urban parks decidedly influence stress reduction compared to an urban built-up city centre. However, both systolic and diastolic blood pressures decreased insignificantly after walking in the park. Similar variables such as their mental and physiological measures on other urban societies (i.e., working adults, population with hypertension, and their encounters) concerning the effect of a short walk with green ecology should be studied further.
- Residential sidewalk gardens and biological conservation in the cities: Motivations and preferences that guide the floristic composition of a little-explored space
Urban Forestry & Urban Greening, Volume 63, August 2021, 127227
Plant diversity in large cities has recently become a subject of intense biological research. Urban green spaces are widely acknowledged to improve people’s quality of life. Unlike in wild areas, plants in urban ecosystems develop in spaces strongly managed by human activity and tend to form different compositions than the natural landscape. Under this scenario, would the motivations and preferences of urbanresidents make it possible to conserve a sample of the local diversity in these spaces? To answer this question, we apply a semistructured survey to 100 homes that have a residential sidewalk garden in Santiago de Chile. Our results show that these gardens are perceived as an essential part of the home and its environment. We recognized three groups of citizens, namely, a utilitarian group (19 %), native group (21 %) and neutral group (60 %). The utilitarian group prefers to grow useful plants, such as for medicine or food. The neutral group does not indicate a preference for particular attributes of plants, which could be an indicator of the extinction of the experience with nature. Most of the participants do not know the origin of the species they grow.However, even when knowledge of native flora is limited ( = 0.96; max = 3.0), citizens recognize the intrinsic value of these species and would be willing to conserve them in their gardens ( = 4.35; max = 7.0). This willingness is also motivated by the set of benefits provided by native plants (e.g., ornamental, ecological, structural or emotional). Greater knowledge of native flora in the native group can be attributed to familiarity; therefore, the presence of these species in residential sidewalk gardens could encourage preferences and decisions aimed at promoting the conservation of local plant diversity.
- Protection of peri-urban open spaces at the level of regional policy-making: Examples from six European regions
Land Use Policy, Volume 107, August 2021, 105480
Peri-urbanisation is a dynamic process consisting primarily of the expansion of artificial areas into natural, semi-natural, and agricultural areas. This process reduces peri-urban open spaces, thus it is threatening peri-urban biodiversity and hampers the provision of ecosystem services. In this manuscript, we introduced the concept of peri-urban open spaces and exemplified it on the level of regional policy-making in the following six European case study regions: Basque Country (Spain), Flanders (Belgium), Gorenjska (Slovenia), Hajdú-Bihar (Hungary), Mazovia (Poland), and Saxony-Anhalt (Germany). Our study aimed (1) to analyse land cover changes related to peri-urban open spaces in the case study regions, (2) to identify and classify policy improvements that are useful to protect peri-urban open spaces, and (3) to provide recommendations for regional policy instruments to improve the protection of peri-urban open spaces. We designed a mixed-method approach combining Geographical Information Systems, an explorative questionnaire, and a semi-quantitative survey to fulfil our research aims. Our results showed that peri-urban open spaces are decreasing in all case study regions but with different scale and dynamics over time. Mostly (non-irrigated) arable land was transformed into non-peri-urban open space. Moreover, we identify 15 policy improvements that are suitable to support the protection of peri-urban open spaces at the level of regional policy-making. Our results indicated a potential for improving the regulatory instruments and showed the usefulness of multi-level governance that better address the protection of peri-urban open spaces at regional level. Using our research results, we provided recommendations for regional policy-makers who are willing to pay more attention to the protection of peri-urban open spaces.
- Understanding the macro-micro dynamics of urban densification: A case study of different sized Indian cities
Land Use Policy, Volume 107, August 2021, 105469
Indian cities face unplanned and rapid urbanization, yet limited studies investigate their urban growth dynamics systematically. Urban land density (ULD) analysis is crucial for developing countries worldwide, especially for populous countries like India. To understand the complexities of urban structure and its expansion, we propose a framework for quantifying urban densification by integrating its macro structure and micro dynamics. Five Indian cities are chosen as study areas based on economic categorization and city size. The macro-structure analysis is performed through a non-linear fitting of concentric density zones to derive an urban land density function (ULDF). The parameters of ULDF define the compactness and dispersion of urban expansion. The micro-urban form analysis is carried out by examining the spatial configuration of ULD. The study reveals that Tier-I city suffered from high compact urban growth. In contrast, Tier-II city with the elevated topography is found to have the highest urban land density at the city center in all studied years compared to the remaining chosen cities. The study also reveals that Tier-II city with plane topography has shown a significant increase in urban land density at boundaries. The rest of the chosen cities of Tier-III have contributed more toward dispersive growth. The spatial configuration of urban densities indicates that Tier-I and Tier-II cities have a close relationship in urban patches and class dynamics. Overall results from macro structure analysis depict that Tier-I and Tier-II cities are interrelated and consistent w.r.t. the ULDF, whereas, Tier-III city and town are explainable inconsistent. This inconsistency can be explained through a micro-urban form analysis. The study reveals the varied characteristics of developing cities, which would help policymakers and urban planners enhance the quality of urbanization and promote sustainable development.
- The economic and ecological benefits of saving ecosystems to protect services
Journal of Cleaner Production, Volume 311, 15 August 2021, 127551
The concept of Ecosystem Services (ES) defines the nature benefits in an anthropocentric way for sustainable development goals. However, a conservation dilemma arises from the question of how much the ES cost and which ES should be prioritized in effective landscape planning. Thus, we test how the balance of economic and ecological values can be useful for improved conservation outcomes. Under a comprehensive meta-analytical approach, we address the monetary values of ES and incorporate habitat quality maps for setting national conservation targets in mainland Portugal. As a practical pathway to achieve sustainability from local to macro scales, we design an integrative approach showing that prioritization models focused on ES can encompass economic and ecological values in balance with the landscape. We find 72 studies with 167 economic estimates based on biophysical, socio-cultural and environmental features. Our results indicate that ES values in Portugal can represent about 12% of its total Gross Domestic Product (GDP), which in turn can ensure key conservation sites for multiple ecosystems. Combining the trade-offs and synergies between ecological and economic benefits of ES, we suggest an integrative strategy to save ecosystems and protect services through cost-effective conservation models. Given the economic and ecological interface of this approach, our findings can be helpful to bridge the gap between environmental economics and conservation science, following three main components – most economic benefits, best habitat quality and less land requirements. This would bring market values on realistic scales, where stakeholders are expecting positive returns.
- 14. A framework for sustainable and integrated municipal solid waste management: Barriers and critical factors to developing countries
Journal of Cleaner Production, Volume 312, 20 August 2021, 127516
Developing countries adopt policies to reduce the negative impacts of large amount of waste generated by accelerated industrialization and rapid urbanization, but these actions are far from establishing procedures that meet society’s needs, especially regarding the management of municipal solid waste (MSW), which requires the cooperation of numerous stakeholders, and a broad plan of action, in terms of sustainability cities’ targets and policies. In this sense, sustainable and integrated solid waste management (S-ISWM) emerges as a solution to address the growing challenges of disposing of MSW in developing countries municipalities. However, to guide S-ISWM implementation there still a need of a framework with a multi-stakeholder and holistic perspective of the MSW management, considering the barriers and critical success factors (CSFs) to achieve it. To this end, a systematic literature review using the PRISMA diagram on the Scopus and Web of Science databases, and then, a content analysis of 75 articles, which met the eligibility criteria, were carried out. As a result, were identified eight barriers, 11 CSFs, which were grouped according to five pillars – public policies, disposal techniques, legal aspects, public-private partnership (PPP) and energy recovery – that affect the municipal S-ISWM and were pointed out ways of implementing these factors in practice. Finally, it was proposed a management artifact – a framework towards S-ISWM – based on state-of-the-art CSFs and barriers, mainly oriented to waste to energy, to the developing countries municipalities. This study offers theoretical, practical, and political implications, serving as a stimulus for the development of public policies with a multidisciplinary approach, providing environmental, economic, and societal contributions, and, thus, encouraging the achievement of the eleventh and the twelfth sustainable development goals.
- Building Information Modeling and Internet of Things integration for smart and sustainable environments: A review
Journal of Cleaner Production, Volume 312, 20 August 2021, 127716
During the last decades, society has increasingly moved towards the adoption of digital solutions in almost every aspect of people’s lives with the aim of enhancing daily activities. At the same time, the environmental impact of the built environment has attracted the attention of public opinion that is gradually perceiving the necessity of limiting its negative effects in order to safeguard the Earth and people’s wellbeing. The Internet of Things is one of the biggest ecosystems that is bringing innovations encompassing digital solutions in almost every sector. On the other hand, the Building Information Modeling approach allows for data sharing among stakeholders, traceability, and the integrated management of the building or infrastructure life-cycle through a 3D informative virtual model. Our study reviews existing research works and technological solutions that integrate these two important topics to enhance the sustainability of the built environment, making it smarter. The presented review analyses the existing papers available in literature from January 2015 to December 2020, to present the best practices in this integration and discuss limitations of the identified solutions. Based on the outcomes of the analysis and aiming at the creation of a solid knowledge basis for the community interested in the sector, a comprehensive modular architecture has been proposed. Finally, new directions for future works are presented by discussing how the proposed architecture can actually facilitate the design and development phases.
- Evaluating the role of commercial parking bays for urban stakeholders on last-mile deliveries – A consideration of various sustainability aspects
Journal of Cleaner Production, Volume 312, 20 August 2021, 127462
In this contribution, we assess the traditional last mile delivery concept and a framework with commercial parking bays for carriers in terms of their sustainability value for urban stakeholders. We evaluate the potential advantages and disadvantages of commercial parking bays and provide routing solutions based on the given context and stakeholder objectives. To ensure the needs of the stakeholders and the possibility of a near future implementation in the dynamic real-world system, we chose a combined approach of simulation and mathematical optimization, which allows us to investigate the concept efficiently and with a high reliability. By means of an agent-based simulation model as well as a mixed-integer linear model, we establish a heuristic routing solution for minimizing both emissions and delivery durations. We consider different scenarios in which customers are visited in a delivery radius, around a specific commercial parking bay. Outside this radius, delivery operations are conducted through second-row parking activities. Our results for the area of investigation show that the investigated scenario featuring a 200-m delivery radius around the parking bays has a 29.8% emission savings potential compared to traditional parcel delivery procedures. Moreover, optimizing the delivery routes with our green vehicle routing approach has indicated an additional savings potential of 26.4% in terms of delivery duration and 16.4% in terms of emission output for traditional parcel deliveries. Concerning the individual evaluation of the logistics context, our results indicate that dedicated commercial parking bays could be attractive to most urban stakeholders when employed utilizing a hybrid approach, combining traditional delivery activities with commercial parking bay fulfillment.
- Coordinating urban construction and district-level population density for balanced development: An explorative structural equation modeling analysis on Shanghai
Journal of Cleaner Production, Volume 312, 20 August 2021, 127646
Balanced development is essential for sustainable development. Investigating the coordination between urban construction and district-level population density can deepen the knowledge of balanced development on the urban scale and promote better delivery of planning policy. This study took Shanghai as an example to explore the influence of three kinds of urban construction – market-driven urban construction, public transportation infrastructure and public service facilities – on district-level population density with longitudinal data (2003–2017). Nine variables were selected through a comprehensive review of the literature and the policy/planning practices of Shanghai. Structural equation modeling (SEM) and stepwise multivariate linear regression (SMLR) were integrated, forming an explorative SEM analysis framework to analyze the significance of the variables and their interplay. The results showed that market-driven urban construction had the most significant influence on district-level population density. However, it was not well integrated with public service facilities. Additionally, public service facilities and public transportation were not evenly distributed. Therefore, policies on improving the public transportation network and coordinating the three types of urban construction is imperative.
- Addressing infrastructure investor risk aversion: Can project delivery resilience ratings help?
Utilities Policy, Volume 71, August 2021, 101225
Risk aversion is a core characteristic of investor decision-making, especially with respect to new asset classes, such as infrastructure. Contracting authorities in need of delivering projects have been keen to address investors’ concerns by providing guarantees and other support. This approach has had an impact on projects’ economic viability and their effective delivery. This paper proposes the use of Transport Infrastructure Resilience Ratings by investors and other stakeholders to complement existing information of projects’ financial risks resulting in a more holistic understanding of their likely outcomes. This potential is demonstrated through examples of projects in the European transport sector.
- Multifaceted intra-city water system arrangements in California: Influences and implications for residents
Utilities Policy, Volume 71, August 2021, 101231
Some cities directly provide drinking water and other utility services to their residents, whereas others contract out these responsibilities in full or in part, with considerable implications for service and non-service outcomes. There is a robust literature considering reasons for city-private provider binaries, as well as a growing number of studies assessing the rise in special district service provision, mixed service delivery arrangements, and inter-municipal service delivery within metropolitan contexts. On the other hand, there are few studies assessing city-level prevalence of these three main provider types jointly, as well as fully accounting for the diversity of institutional arrangements in drinking water service within individual cities.
In this study, we construct an empirical profile of and analyze influences on diverse city-level water service provider arrangements using a dataset compiled for all 482 cities in California. Our analysis shows that 80% of cities are served by either a municipality, a private, investor-owned utility or a special district, with special districts being more common than private providers. Moreover, 20% of cities had more than one service provider, and 68% of these cities were served by more than one system type, including many where municipal and private providers co-existed. Using multivariate regression techniques, we analyze influences on different types of city-level drinking water service arrangements. We find that city incorporation date most profoundly influences the mix of water systems in cities, especially arrangements involving special districts or multiple system types. We also find that cities which run their own water system exclusively are more likely to institute conservation policies, and provide suggestive evidence that residents living in cities served by multiple water systems are exposed to wide variance in water rates. Water system fragmentation within city boundaries thus has implications for resource management policy and equity in intra-city resident essential service outcomes.
- Ownership and sustainability of Italian water utilities: The stakeholder role
Utilities Policy, Volume 71, August 2021, 101228
After several decades, the political and academic debate on water governance is still dominated by arguments about whether private sector involvement increases both efficiency and the level of investment within the industry. These arguments could appear reductive, especially in a context like Italy, which is dominated by public and mixed-ownership water utilities. The aim of this paper is to analyze how the socio-economic context and stakeholders’ interests can influence the relationship between ownership structure and water utilities’ sustainability performances. Analyzing six case studies, this research shows that the institutional context may influence both the water governance and utilities’ performance. The theoretical and managerial implications are discussed.
KHOA HỌC VÀ CÔNG NGHỆ TRONG LĨNH VỰC KIẾN TRÚC, XÂY DỰNG
- 3D visual inspection system framework for structural condition monitoring and analysis
Despite the increase in algorithmic solutions to enhance manual, time-consuming and inaccurate Structural Condition Monitoring assessment, this field currently lacks an effective framework of presenting the output of these algorithms in an understandable and repeatable manner to structural examiners. To solve this issue, a 2D/3D Visual Inspection framework is proposed to allow the creation of a system that detects, visualizes and evaluates structural defects. The resulting system allows structural examiners to conduct a thorough, intelligent structural condition monitoring assessment, who wish to utilize AI technology. This system consists of the Visual Analytics Interface and the 3D Virtual Inspector. The Visual Analytics Interface is an interactive dashboard formed by the following components: the Map, the Graph and the Panel. The 3D Virtual Inspector allowing examiners the exploration of the structural defects with superimposed augmented visualization onto the 3D structure reconstruction. This work presents a case study focused on structural examination of tunnels to demonstrate the applicability of the proposed system.
- Bibliometric analysis of Building Information Modeling, Geographic Information Systems and Web environment integration
Automation in Construction, Volume 128, August 2021, 103757
The integration of Building Information Modeling (BIM) and Geographic Information Systems (GIS) within the Web environment is a promising approach that greatly enhances the capabilities of the aforementioned environments through the wide range of technology solutions used on the Web. This paper aims to reveal the trends of research in BIM, GIS, and Web integration and discuss the challenges and potential opportunities of such integration in terms of the most common uses in construction. The bibliometric analysis used as the method, compared to conventional literature reviews, reduces the likelihood of subjective judgments. The methodology used is based on a set of five research questions. To answer these, bibliographic coupling is used to analyze the publications datasets, specifically, co-citation networks, co-authorship networks, and the co-occurrence map of keywords. This review contributes to the field in raising awareness of the knowledge composition of BIM, GIS, and Web integration in the last decade, dominant research topics, the most recent trends, and the most pressing issues and use cases analyzed in the current studies related to BIM, GIS, and Web integration, thus identifying gaps and defining future research areas on the topic. The research shows that the number of developments focusing on BIM, GIS and Web integration has been continuously growing with a sudden increase after 2016. The study also revealed that the research work in this area consists of disjointed and fragmented research studies and has been conducted mainly in isolated clusters. Gaps and critical areas for future research include BIM, GIS, and Web interoperability solutions, standardization, BIM model processing and performance optimization, data exchange and storage.
- Automated crack pattern recognition from images for condition assessment of concrete structures
Automation in Construction, Volume 128, August 2021, 103765
Evaluating the appearance of cracks on concrete elements is necessary during condition assessment. Most imaging techniques related to crack identification focus on detecting cracks and measuring basic dimensions of cracks. However, condition assessment of an element from visible cracks requires further information, of which characterizing the crack pattern is necessary. To achieve this, this paper proposes an automated approach to recognize concrete crack patterns from images. By analyzing the characteristics of structural and non-structural cracks, a binary classification of crack patterns into isolated patterns and map patterns is proposed. The recognition of crack patterns is performed through similarity comparisons using DISTS index. Various parameters that may affect the performance are investigated through several experiments conducted using real-world images. According to the experimental results, the proposed method is shown to successfully recognize crack patterns with an accuracy of over 96%. Recommendations are further proposed to enhance the performance of the method.
- Rapid safety monitoring and analysis of foundation pit construction using unmanned aerial vehicle images
Automation in Construction, Volume 128, August 2021, 103706
With the large-scale development and construction of urban underground spaces, the safety monitoring of foundation pit construction has gained much attention. Current safety monitoring of foundation pits is often achieved through manual onsite measurements with complex equipment and relies on complicated methods, which are labour intensive, time consuming, and tend to ignore the risk of accidental collapses caused by serious local deformation. To address this issue, this study develops a rapid safety monitoring and analysis method for foundation pit construction using Unmanned Aerial Vehicle (UAV) images. The safe inclination angle of the foundation pit slope was proposed as the safety-monitoring index. Taking the images of the foundation pit captured by the UAV as input, point cloud reconstruction and surface fitting were carried out. The local deformation distribution was introduced to evaluate the local safety state of the foundation pit. The experimental results validate the potential advantages of the method.
- Centimetre-range deformations of built environment revealed by drone-based photogrammetry
Automation in Construction, Volume 128, August 2021, 103787
Deformation monitoring is an important component of the construction process and maintenance. Conventional point-wise surveying methods, however, tend to be time consuming, labour-intensive and may pose a risk to the surveyors. Instead, unmanned aerial vehicles in combination with structure-from-motion photogrammetry are now capable of high-accuracy contactless surveys. This study hence investigates road structure deformations identifiable by drone surveys from 40, 50 and 60 m flight altitudes. The surveys were georeferenced in 21 different ground control point configurations using integrated georeferencing. Comparisons between the resulting models and terrestrial laser scanning ground truth yielded the optimal configurations. The determined deformation estimates by using the optimal georeferencing configurations were validated using high-precise levelling results, which yielded the best deformation residual RMSE estimate of 0.29 cm for the 50 m altitude survey. These tests demonstrated that the proposed method can be employed for quick and contactless quantification of magnitude of built environment deformations.
- Semi-supervised semantic segmentation network for surface crack detection
Automation in Construction, Volume 128, August 2021, 103786
The detection of surface crack is essential to ensure the safety and the serviceability of civil infrastructure. The automatic method is highly efficient and the test results are objective, which makes it gradually replace conventical manual inspection. Recently, semantic segmentation algorithms based on deep learning have shown excellent performance in crack detection tasks. However, the commonly used fully supervised segmentation method requires manual annotation of large amounts of data, which is time-consuming. In order to solve this problem, we propose a semi-supervised semantic segmentation network for crack detection. The proposed method consists of student model and teacher model. The two models have the same network structure and use the EfficientUNet to extract multi-scale crack feature information, reducing the loss of image information. The student model updates weights through the gradient descent of loss function, and the teacher model uses the exponential moving average weights of the student model. During training, the robustness of the model is improved by adding noise to the input data. When using only 60% of the annotated data, our method achieves an F1 score of 0.6540 on the concrete crack dataset and 0.8321 on the Crack500 dataset. The results show that our method can greatly reduce the workload of annotation while maintaining high accuracy.
- A deep learning approach for fast detection and classification of concrete damage
Automation in Construction, Volume 128, August 2021, 103785
The detection and classification of concrete damage are essential for keeping the infrastructure in good condition which have become a focused area. It is worth noting that the inference speed and accuracy of object detection algorithms are the key issues in concrete damage detection tasks. This research has made the following contributions to solving these problems. Firstly, a concrete damage data set is prepared. The data set consists of 5000 images containing the types of crack, spot, rebar exposure and spalling damage. Secondly, the object detection algorithm is optimized by depthwise separable convolution, inverse residual network and linear bottleneck structure. The experimental results show that the inference speed of the improved object detection algorithm is 24.1% and 53.5% higher than that of the original network, respectively. Compared with the original YOLO-v3 and SSD object detection algorithms, the complete detection accuracy of the network reaches 64.81% and 64.12%, which increased by 3.25% and 4.04%, respectively.
- Influences of vernacular building spaces on human thermal comfort in China’s arid climate areas
Energy and Buildings, Volume 244, 1 August 2021, 110978
Vernacular building spaces are key elements in adjusting thermal environment of buildings and thermal adaptation of residents. This paper analyzed the comprehensive influence of building spaces on the thermal environment, thermal adaptation behaviors and thermal responses of residents. Regarding the indoor and semi-open spaces of vernacular buildings in arid climate areas of Turpan, China, a one-year survey of building thermal environment and residents’ thermal comfort was conducted. It was found that the thermal environment of indoor and semi-open spaces is substantially different, which provides comfortable living spaces for residents at different times. And the thermal adaptation behaviors were closely related to the building spaces. In addition, residents have different thermal comfort in indoor and semi-open spaces, including the neutral temperature, the acceptable temperature and preferred temperature. Among them, the neutral temperature differences in transitional seasons and summer were 1.1 °C and 0.9 °C, respectively. The differences in the value of 80% acceptable temperature were 2.2 °C and 2.7 °C, respectively; and the difference in preferred temperature was 1.6 °C in summer. Further analysis showed that the thermal environment of vernacular buildings in Turpan affected residents’ thermal adaptation behavior and thermal comfort. The results indicated that the diverse spaces of vernacular buildings in Turpan can create different thermal environmental conditions for buildings and can stimulate thermal adaptation behaviors of residents, thereby improving residents’ thermal comfort and thermal adaptability.
- Power allocation by load aggregator with heterogeneous loads using weighted projection
Energy and Buildings, Volume 244, 1 August 2021, 110955
With the recently increasing adoption of transactive energy markets, the role of a load aggregator is becoming increasingly important. Among the many tasks of an aggregator, the task of managing the electricity consumption among a group of grid-interactive efficient buildings according to the demand on the grid is taken up. Specifically, the task of allocating a certain amount of power among the participating customers while respecting their preferences and comfort is considered. Modeling this as an aggregate flexibility, the virtual battery conditions that are employed to verify the feasibility of a candidate power profile are derived. A feasible power profile, when allocated, satisfies specified comfort bands. To determine the ideal power requirement of the loads, the model-free control method is employed. The feasible power profile is allocated by embedding the customers’ preferences through weights, posing the power constraint as a hyperplane, and employing a weighted projection from the ideal power requirements onto the constraint plane to solve the considered task. The proposed method is computationally efficient and scalable to any number of heterogeneous thermostatically controlled loads in buildings.
- Smart versus conventional lighting in apartments – Electric lighting energy consumption simulation for three different households
Energy and Buildings, Volume 244, 1 August 2021, 111009
For residential environments, energy-reducing strategies to cope with user activities and behaviour are currently limited mainly to the implementation of improved lighting technology. Non-residential environments have already been operating smart lighting systems for many years. These systems use advanced and integrated lighting technology, including an internet-based network for data communication. As user activities and behaviour in the residential sector significantly differ from the non-residential one; thus, a non-residential energy optimisation potential may not necessarily be achievable and directly translatable to the residential sector. Also, the architectural typological variety amongst residences may be larger than non-residences. In residential buildings, the effect of the composition of a household (domestic establishment) and user activities on smart lighting systems’ consumption and efficiency are not explicitly investigated before. In this light simulation study in Sweden, the electric lighting energy consumption for a two-room apartment was modelled for three different household scenarios using DIALux Evo and DIVA-for Rhino. The household scenarios were composed based on input by 12 existing Swedish households and incorporate residential occupancy variety. The study’s findings suggested that the appropriate use of smart lighting solutions, including optimised sensor applications, has the potential to save more than 50% of electric lighting energy consumption compared to non-smart systems. The study demonstrated promising simulation results specifically focussing on (smart) lighting application alternatives in the residential sector.
- Generative design and performance optimization of residential buildings based on parametric algorithm
Energy and Buildings, Volume 244, 1 August 2021, 111033
As passive green design and performance optimization are very important in the early design stage of green residences to reduce building energy consumption, energy-efficient green design and artificial intelligence technology are combined in this work for the design of residential buildings. A parametric generative algorithm is developed to automatically generate design schemes of typical Chinese urban residences based on performance-oriented design flow. By summarizing the workflow of architects, the algorithm based on the technical route is as follows: 1) spatial form features extraction of residence database; 2) automatic generation and energy simulation of new design schemes; 3) evaluation and screening of generated schemes. The generative algorithm is formulated with Rhino/Grasshopper and Python. Via a residence design case in Beijing, the design scheme with the lowest cooling and heating load among 1,595 automatically generated schemes is deemed as the optimal scheme. The total load of the optimal scheme is 15.8% lower than that of the worst scheme and 4.2% lower than that of the original scheme. Therefore, the parametric generative design of residences is able to facilitate passive green design in the early design stage and enhance energy efficiency without the increase of construction costs.
- Ecological life cycle analysis-based installation capacity determination of building energy-supply systems
Energy and Buildings, Volume 244, 1 August 2021, 111002
Based on the ecological life cycle analysis (Eco-LCA) theory, this study focused on constructing the ecological life cycle analysis framework and model of a combined cooling heating and power (CCHP) system equipped a gas internal combustion engine (GICE) in which the ecological cumulative exergy consumption (ECEC) is minimized to maximize ecological sustainability. This method solves the problem of low-efficiency operation resulting from the implementation of an unsuitable GICE installation capacity; additionally, the ecological view is first introduced into the stage of scheme decision to achieve the maximum ecological benefits. Moreover, a case study that involved implementing the GICE capacity design in a typical hospital building in Chongqing was performed to demonstrate the capability of the proposed model. The simulation results revealed that the operation-stage ECEC accounts for approximately 97% of the total ECEC for each design scheme. The 600-kW GICE installation capacity yielded the best ecological sustainability under the condition of satisfying the energy demand of the building; the ECEC of the CCHP system with a GICE was approximately 4.45E + 18 seJ, and the GICE equivalent full-load running time in one typical year is approximately 3289 h. In comparison to system of the case building, the installation capacity of GICE equipped according to the normal economic index is 400 kW. It shows that the optimal size of GICE is not always the same from economic and ecological perspectives, but the Eco-LCA can make more objective authentic decision due to without the arbitrary weighting of different ecological factors. Further, a simplified Eco-LCA of the CCHP system with GICE method is given out and it can provide reference for related engineering application.
- Canopy contribution to the energy balance of a building’s roof
Energy and Buildings, Volume 244, 1 August 2021, 111000
Green roofs are complex systems governed by intricate transport phenomena, which are frequently solved using simplified and empirical models. This paper describes a numerical model capable of solving the conservation equations that govern the unsteady nonlinear coupled moisture and heat energy transport through a multi-layer green roof composed of a structural support, a water storage layer, growing medium and canopy.
To get an accurate insight into the role of different variables that affect the hygrothermal behaviour of green roofs, the temperature on the outer surface, as well as the outflow and inflow heat fluxes, were computed for different roof models and environmental conditions. A sensitivity analysis was performed to understand the role of the different layers and the canopy’s geometrical composition (e.g. vegetation coverage, plant height and leaf area index) in the energy balance of the building’s roof. Finally, to foresee the behaviour of the full canopy system under real climate conditions, weather data with distinct climatic characteristics from Bragança (Portugal) and Seville (Spain) were used.
The simulated green roofs use insulation cork boards (ICBs) to replace both the water storage and insulation layers. Due to the intrinsic thermal characteristics of ICB (an ICB layer of 0.2 m allowed us to reduce the heat flux by about 58% compared with an ICB layer of 0.05 m), these roofs are expected to improve interior comfort and save energy. Although the ICB and soil layers made the greatest contribution to the thermal insulation, the characteristics of the vegetation were found to be of substantial importance to the overall performance of the green roof. The leaf area index (LAI) was the most relevant vegetation variable (a change from LAI = 2 to LAI = 5 decreased the inflow heat flux by about 27%), while difference in plant height did not lead to any significant change in inflow heat flux.
- A dynamic state-space model for predicting the thermal performance of ventilated electric heating mortar blocks integrated with phase change material
Energy and Buildings, Volume 244, 1 August 2021, 111010
Thermal active building system (TABS) is promising to increase the flexibility of building energy systems. In this research, the thermal characteristics of a ventilated mortar block in the operation mode that the air is directly exhausted are analyzed by models. The block is integrated with phase change material (PCM) and ventilation tubes to increase both heat storage capacity and heat extraction flexibility. The simplified thermal model of the block, which combines the thermal network model and number of transfer unit model (NTU), is established and rearranged in standard state-space form based on the experimental system. The calculation process is also improved. Different modeling methods are compared, and the accuracy of the model is also validated by the testing data of three kinds of ventilated mortar blocks, which have different layers of PCM inside. Furthermore, parametric analysis is also conducted. The results show that for the current operational mode where the air is directly exhausted, the thickness of the mortar block and the diameter of the tube have a dominant impact on the surface and outlet air temperature, while velocity has a lower impact on the outlet air temperature.
- The regional disparity of per-capita CO2 emissions in China’s building sector: An analysis of macroeconomic drivers and policy implications
Energy and Buildings, Volume 244, 1 August 2021, 111011
There are significant regional differences in CO2 emissions in China’s building sector. Analyzing and understanding this geographic inequality and its drivers is crucial for balanced regional development and greenhouse gas (GHG) emissions reduction. In this paper, we estimated the CO2 emissions of China’s building sector at the provincial level and then calculated the Theil Index of per-capita CO2 emissions generated from different building types. Based on these results, a Kaya identity was applied to analyze the drivers of the inequality in CO2 emissions across China. We found that the inequality index of the different types of buildings makes a significant difference. In general, the Theil Index for public buildings and urban buildings is higher than that for rural buildings. Income, energy intensity and energy mix are the principal drivers of regional disparity of per-capita emissions. Economic growth helps to narrow regional disparities for residential buildings, but its contribution is not significant for public buildings. For all building types, energy intensity is the primary contributor to emissions inequality, and the imbalanced implementation of energy efficiency policies is a leading factor. Energy mix plays an increasing role in the regional disparities of per-capita CO2 emissions, especially for rural buildings. Reducing these regional disparities is crucial to China’s goal of achieving peak GHG emissions and reaching carbon neutrality. This paper highlights the importance of per-capita CO2 emissions in formulating carbon peak planning, allocating regional emissions reduction targets, formulating building energy policies and allocating low-carbon resources.
- Regional climate effects on the optimal thermal resistance and capacitance of residential building walls
Energy and Buildings, Volume 244, 1 August 2021, 111030
Energy efficiency in residential buildings can be improved considerably by optimizing the allocation of thermal resistance () and capacitance () of external walls. However, it is difficult to identify which allocation yields the minimum heat loss or heat gain for a given climate region, due to a lack of understanding of how regional climate affects optimal allocation. In this study, we determine the effect of the climate characteristics on the development of optimal allocation by combining the network model and the particle swarm optimization algorithm, taking five representative climates in different Chinese cities as examples. The energy efficiency potential and the ratio of heating to cooling load are introduced to comparatively analyse the energy savings after optimization for the five cities. The results indicate that the energy efficiency potential of residential buildings in Harbin is the largest, ranging from 6.2% to almost 20.6% for different total building capacitance. In Harbin, Beijing and Kunming, the energy efficiency potential is larger than those in Guangzhou and Shanghai, which is attributed to the larger heating to cooling load ratio of the former than that of the latter. An approximately linear relationship between the energy efficiency potential and the ratio of heating to cooling load is also built to fast predict the maximum energy savings for any given climate regions. This study could serve as useful references for the optimal design of thermal resistance and capacitance in different climate regions to save energy of residential buildings.
- An inquiry into the capabilities of baseline building energy modelling approaches to estimate energy savings
Energy and Buildings, Volume 244, 1 August 2021, 111054
While baseline energy modelling approaches for buildings are progressing to meet the demand for measurement and verification (M&V) of savings of an energy performance contract, more robust and insightful modelling approaches are needed. This study compares four baseline modelling approaches (e.g., change point, nonlinear autoregressive exogenous models (NARX), Gaussian process, and ensembles of trees) in terms of predictive accuracy and operational insights. The approaches were selected based on preliminary study and employed on pre- and post-intervention data gathered from twelve commercial buildings in Ottawa, Canada. Changes in the post-intervention energy use were estimated by comparing the predicted data with measured data for the individual buildings. The known primary intervention in these buildings was implementing commercially available smart building technologies that identify and address operational suboptimalities. A deeper analysis of one building’s automation system data indicates that energy savings were largely due to simple corrective actions such as eliminating the concurrent operation of heating and cooling coils of an air handling unit. The results show that saving estimates are largely affected by the choice of baseline energy modelling approach. NARX outperformed all other modelling approaches regarding accuracy and data fitting capability. On the contrary, the change point modelling approach offered insights into the operational performance of the buildings.
- Current and future coating technologies for architectural glazing applications
Energy and Buildings, Volume 244, 1 August 2021, 111022
This paper presents a comprehensive review of the current state-of-the-art coating technologies for glazing applications. The main objective is to collect and present current commercially available technologies on today’s market and future research prototypes to identify the most promising coating technologies. Several static coating technologies with fixed optical properties are compared, including low emissivity, electrothermal and photothermal coatings. Low-E coatings are the current industry standard and have almost reached their full energy-saving potential. Hence, electrothermal coatings that convert electricity to heat by the Joule effect are discussed, together with their limitations of needed power supply. To overcome these issues, photothermal coatings have been proposed to improve the glazing thermal performance by absorption of ultra-violet and near-infrared radiation. On the other hand, dynamic coatings can modulate solar gains by switching between clear and tinted states in response to external stimuli. Electrochromic and gasochromic coatings are still limited by high costs. In comparison, photochromic and thermochromic coatings are more accessible and less complex passive technologies, although photochromic coatings are still hindered by low bleaching rates and poor cyclic stabilities. In comparison, thermochromic coatings are more mature, especially those based on vanadium dioxide. This review shows that both static and dynamic technologies thrive to enhance optical and thermal performances while providing an opportunity for the realization of durable next-generation dynamic windows. In particular, the development of passive dynamic hybrid photo-thermochromic coatings seems the most promising trajectory.
- Field study on thermal comfort in nursing homes in heated environments
Energy and Buildings, Volume 244, 1 August 2021, 111032
Considering the progressive population aging, the fact that old people spend around 90% of their time indoors and the high energy expenditure of heating systems, thermal comfort in nursing homes should be analysed. The aim of this study is to analyse the thermal comfort during the winter of elderly people living in nursing homes (residents) and compare it with the thermal comfort of caregivers and therapists (non-residents). Longitudinal field measurements were conducted in 25 common rooms of five nursing homes in a Mediterranean climate during the winter, from January to March 2019. Room air temperature (Ta), relative humidity (HR%), mean radiant temperature (Tr) and air velocity (va) were recorded using a Delta Ohm HD32.1 instrument with an anemometer, thermometer and a black globe thermometer. “Right-here-right-now” thermal responses of occupants were collected using a face-to-face questionnaire delivered intermittently. A total of 881 questionnaires were collected and then matched against concurrent indoor and outdoor thermal conditions. The results indicate that residents of nursing homes in the Mediterranean climate were less sensitive to variations in room temperature than therapists and caregivers, and less sensitive than found in previous studies conducted in non-elderly adults. The neutral temperature for residents was 21.6 °C while for caregivers and therapists it was 21.9 °C. The results also showed that clothing adaptation to the activity of caregivers would increase their thermal comfort and might help thermal adaptation to residents’ thermal needs. The modification of temperature setpoints in nursing homes based on the results of this study could influence energy use and should be carefully considered by policy makers and nursing homes’ facility managers.
- Evaluation of sustainable strategies and design solutions at high-latitude urban settlements to enhance outdoor thermal comfort
Energy and Buildings, Volume 244, 1 August 2021, 111037
Driven by the necessity to design resilient and prosperous cities and to counteract the impacts of climate change, this study aims to shed light on the interactions between microclimate, urban built environment, and the outdoor thermal comfort (OTC) conditions at a university campus in Trondheim, Norway. This paper calls into question up to which degree four typical microclimatic design solutions can enhance OTC in high-latitude areas which are generally characterized by strong seasonal variability in meteorological conditions, particularly in solar radiation. An on-site measurement campaign in autumn 2019 for the validation of numerical simulations with ENVI-met were carried out. Solar access proved to be the key parameter to improve OTC by a Predicted Mean Vote of up to 1.0 in the investigated climatic situation. Moreover, wind sheltering resulted in an increase of OTC, although not as pronounced and on a smaller spatial scale. Changing the buildings’ surface material resulted in no significant changes in microclimatic conditionsAt a higher wind speed (8 m/s), wind sheltering becomes more effective in improving OTC than solar access. This study underlines the importance of microclimatic assessments in order to understand the effect of different interventions with the urban environment on OTC at high‐latitude urban settlements.
VẬT LIỆU XÂY DỰNG
- Enhancement of strengths of high-calcium fly ash geopolymer containing borax with rice husk ash
Journal of Building Engineering, Volume 40, August 2021, 102762
The objective of this study was to investigate the microstructure and mechanical properties of a high-calcium fly ash geopolymer prepared with borax modified by the addition of rice husk ash (RHA). The sodium silicate was replaced with borax, on an equal mass basis, at 0, 10, 20, and 30%. The results showed that the use of borax instead of sodium silicate reduced both the compressive and flexural strengths. The strength decreases when borax was used were related to the increase in the crystalline nature of the reaction products caused by the decreases in the Si/Al ratios of the gel phases formed. Moreover, incorporating 3.6–6.0% RHA into geopolymer mortars containing either hydrated borax or anhydrous borax led to an improvement in the compressive strength due to the formation of a Ca-modified N-A-S-H gel with a high Si/Al ratio during the reaction.
- Durability of the hydrophobic treatment on brick and mortar
Building and Environment, Volume 201, 15 August 2021, 107994
Hydrophobization lessens the water absorption by facade materials and is thus presumed to reduce moisture problems in internally insulated facades. However, to do this it should retain the water repellency performance throughout aging. The aim of this study is to evaluate the impact of aging on the durability of the hydrophobic treatment on bricks and mortars. The resulting absorption coefficient, after 635 repeating artificial aging cycles of alternating UV radiation (102 min) and water exposure (18 min) reveals that the hydrophobic layer maintains its water repellency performance both in brick and mortar. The samples were treated with two different water repellent agents in different concentrations and tested for capillary water uptake. Additionally, the findings show that cycles of weathering could contribute positively to further reduction of the absorption coefficient of hydrophobized brick and mortar samples. Subsequently, Karsten tube tests on samples from artificial aging illustrate the same water repellency performance as mock-up walls exposed to ambient conditions, six years after being hydrophobized. Contact angle measurements before and after artificial aging reveal that the beading effect declines through aging. However, the beading effect seems to be just a surface effect affected by UV-light. Moreover, after aging, hydrophobized brick and mortar samples, tested by visual inspection, maintain their appearance while untreated samples show signs of efflorescence. In total, these findings indicate that the water uptake of hydrophobized brick or mortar remains very low after aging including water spraying and UV light.
- Recycling of rice husk waste for a sustainable concrete: A critical review
Journal of Cleaner Production, Volume 312, 20 August 2021, 127734
The punitive environmental legislation set by the global community has shifted the direction of research involve in construction industry towards the utilization of secondary raw materials in designing and constructing new structures. Rice husk (RH) is a by-product obtained from the rice mill process whose generation accounts up to 200 kg per ton of rice. The existing literature showed the vast potential of using rice husk ash (RHA) as a replacement for cement or as admixtures. This paper aims to critically review previous studies on RHA as a waste material. The utilization of this waste in concrete contributes to nurturing more sustainable and greener development, thereby lessen carbon footprints and minimize solid waste disposal issues. A state-of-the-art-review of literature on the use of RHA is presented in this paper. The impact of RHA on the properties of concrete such as workability, density, compressive strength, flexural strength, splitting tensile strength, modulus of elasticity, durability properties as well as its impact on sustainability are compiled. In addition, the technical results are complimented with the microstructural analysis evaluated through scanning electron microscopy (SEM). From the data garnered, it is postulated that RHA beneficially enhance the mechanical strengths coupled with improvement of resistant to sulfate and acid attack. This paper advances novel recommendations and directions for future research towards the application of green RHA-based construction products.
- Effective construction and demolition waste management assessment through waste management hierarchy; a case of Australian large construction companies
Journal of Cleaner Production, Volume 312, 20 August 2021, 127790
The construction industry accounts for an enormous quantity of construction and demolition waste (CDW) where its improper management jeopardizes social, environmental, and economic resources. Although several studies have investigated some aspects of construction and demolition waste management (CDWM), there is a substantial need to empirically analysing effective construction and demolition waste management (ECDWM) considering its contributing factors and the CDWM hierarchy (CDWMH). A framework was proposed to assess the effectiveness of CDWM using CDW stakeholders’ attitudes (CDWSA), CDWM within project life cycles (CDWPLC), CDWM with respect to sustainability (SCDWM), and CDWM tools (CDWMT) as factors that effectively affect CDWM, and CDWMH as the most effective strategy to manage CDW, leading to the effective management of CDW. This study analyzed ECDWM in Australia. Thus, 108 large construction companies were approached via an online questionnaire. Data were analyzed through partial least squares based structural equation modelling using SmartPLS. Results (path coefficients) could prove that CDWSA was the most effective factor to CDWM, while CDWPLC was the least effective (ineffective). In addition, recycling strategy received more attention than reusing and reducing strategies, which contrasts with the nature of CDWMH. The study is relevant for CDW professionals as well as academicians involved in CDWM.
- Copper entrapment and immobilization during cement hydration in concrete mixtures containing copper tailings
Journal of Cleaner Production, Volume 312, 20 August 2021, 127547
The use of copper tailings as supplementary cementitious material can reduce the environmental impacts of concrete production and the mining industry. A key concern limiting its application is the potential leaching of toxic metals from the cementitious matrix, especially copper. To analyze and reduce the risk of leaching, the mechanisms by which copper is entrapped in the cementitious matrix were investigated, by combining microscopic and spectroscopic approaches. Decreasing the water-to-binder ratio was statistically relevant to reduce copper leaching. Scanning Electron Microscope micrographs allowed to spatially localize enriched copper clusters within the cementitious hydration products. In the early stages of the cementitious hydration (i.e., 24 h), no spatial correlation between copper and hydration products was found; however, after seven days, copper was spatially associated with calcium silicate hydrates. Cu K-edge X-ray absorption near edge structure spectroscopy provided insights into the chemical speciation of copper in the cementitious matrix. It showed that copper sulfide and oxide phases persisted, whereas the copper sulfate phases were prone to dissolution and reprecipitation as cupric hydroxides induced by the relatively high pH from calcium hydroxides formed during hydration. Promoting the formation of hydration products can further reduce copper leaching from the alkaline cementitious matrix. A better understanding of metal entrapment mechanisms could lead to new strategies that reduce the mobility of toxic elements when using copper tailings, increasing their use as a replacement of cement. With this knowledge, it is expected to answer if it is possible to improve the copper entrapment into the cementitious matrix and if there is a risk of leaching once is entrapped.
- Development of an eco-friendly ultra-high performance concrete based on waste basalt powder for Sichuan-Tibet Railway
Journal of Cleaner Production, Volume 312, 20 August 2021, 127775
Generally, tunnel waste is stacked in the slag field nearby for landfilling, which is harmful to sustainable development. The broken rocks and rock powder among the tunnel waste can be recycled to produce machine-made sand, producing many by-products calling rock powder. Based on the practical project, three types of waste basalt powder (BP), from tunnel excavation waste and by-products (rock powder) of machine-made sand producing from tunnel excavation waste in Sichuan-Tibet railway construction sites, was used to prepare an eco-friendly UHPC. The BP is used to replace the cement and is included in the design UHPC based on Modified Andreasen &Andersen particle packing model (MAA). Moreover, the chemical and physical behaviors and ecological evaluation of the designed UHPC and UHPC pasted were discussed. The results showed that when BP (Specific surface area 4.6582 m2/g) replaces up to 15%, the highest compressive strength of designed UHPC (220 MPa) was obtained. Compared with quartz powder, the pozzolanic activity of BP was generally low and increased with the increase of reaction temperature. However, the presence of BP and its fineness in UHPC pastes increased the values of the total autogenous shrinkage and decreased the total heat release at an early age of designed UHPC pastes, this effect is more pronounced with temperature increasing. Based on a quartering method with embodied carbon dioxide emissions and the compressive strength, UHPC with waste BP reduced embodied carbon dioxide and possessed higher compressive strength and lower environmental impact than the control samples of UHPC.
- Benefits of a regional co-processing scheme: The case of steel/iron and cement industries in Vietnam, Laos, and Cambodia
Journal of Cleaner Production, Volume 312, 20 August 2021, 127702
South-East Asia has one of the highest economic growth rates in the world. Although industrial activity is rapidly expanding, production practices to increase material circularity and reduce environmental impact have yet to see sufficient progress. This article analyses the environmental benefits of implementing a regionally based co-processing scheme between the iron-steel and cement industries of three emergent South-East Asian economies: Vietnam, Laos, and Cambodia. Vietnam, already ranked as the 8th largest cement producer, can be a crucial contributor to a more symbiotic exchange of wastes with regional neighbours. A plan to increase the co-processed iron/steel slag at cement facilities (from 1 to 10 per cent) would translate into substantial gains in material circularity (0.83–8.33 M. tons of raw material savings per year) and carbon emission reductions in the region (0.95–9.07 Mt CO2, i.e. 1.6 to 15.6 per cent of business as usual scenarios equal to reductions of 6 per cent of the total emissions). This scheme could provide further benefits over a nationally self-oriented strategy, revealed by the levels of material exchange within the countries. However, several considerations are essential to make such a scheme feasible. We discuss these critical factors, which are fundamental for a prospective join industrialisation strategy.
- Interaction of biopolymer with dispersive geomaterial and its characterization: An eco-friendly approach for erosion control
Journal of Cleaner Production, Volume 312, 20 August 2021, 127778
Addition of natural polymer or biopolymer is considered as a novel, cost-effective and eco-friendly soil modification approach mainly pertaining to erosion stability. The present study focuses on the interaction of three types of biopolymer i.e., xanthan gum, guar gum and carboxymethyl cellulose to stabilize two dispersive industrial waste materials i.e., fly ash and coal mine overburden soil. The results found that all the three biopolymers enhanced the index and geotechnical properties of fly ash and mine overburden due to their high viscosity, aggregation, adsorption and cross-linking bond formation. However, the rate of enhancement varies with the type and concentration of biopolymer. The biomodified soil were evaluated for erosion stability against wind and water by performing pinhole test, cylindrical dispersion, surface resistance and water retention test. It concluded that a very minimal fraction, 1% of biopolymer solution could mitigate the dispersiveness of the geomaterial. Additionally, the results of microscopic analysis by scanning electron microscope assist to correlate the morphological changes with the engineering properties of biomodified soil due to the interaction of soil with the long-chained biopolymers strings. Finally, leachate and cost analysis of the biopolymer modified material was assessed to evaluate the efficiency of the biomodification.
- Preparation and characterization of ultra-high-strength and ultra-high-ductility cementitious composites incorporating waste clay brick powder
Journal of Cleaner Production, Volume 312, 20 August 2021, 127813
Large quantities of waste clay bricks from construction and demolition (C&D) waste are currently stockpiled in landﬁlls, which is an environmentally, technically, and economically detrimental procedure. In this work, waste clay bricks powder (WCBP) was assessed to determine its feasibility as an alternative to cement for ultra-high-strength and ultra-high ductility cementitious composites (UHS-UHDCCs). The influences of WCBP on the fluidity, hydration, mechanical properties, fiber/matrix interface performances, autogenous shrinkage, and ecological overload capacity of UHS-UHDCC with different replacement levels ranging from 0 to 50% were investigated. The results indicate that WCBPs reduce the fluidity of the UHS-UHDCC matrix. WCBP content of 20% slightly accelerates the hydration process and exhibits the highest compressive and flexural strength in the specimens. Moreover, all UHS-UHDCCs achieve strain-hardening characteristics and exhibit a tensile strain capacity of 3.18–5.47%. UHS-UHDCC with 20% WCBP obtains excellent ultimate tensile stress and tensile strain capability, reaching around 9.34 MPa and 3.18%, respectively. The performance of the interface frictional bond () with different WCBP content was obtained through single-fiber pullout tests, which reasonably explained the macroscopic tensile properties of UHS-UHDCC. The average interface frictional bond () between the fiber and matrix of UHS-UHDCC reaches the maximum 1.72 MPa in the WCBP20 specimen. The average slip hardening coefficient () of UHS-UHDCC is distributed between 0.0031 and 0.0075 and tends to be excellent in the WCBP20 specimen. The theoretical fiber bridging stress vs crack displacement relationship of UHS-UHDCC was calculated through the limitation of interface parameters, which had an excellent correlation with the experimental results. Furthermore, the introduction of WCBP remarkably reduces the autogenous shrinkage of UHS-UHDCC. The ecological overload capacity of UHS-UHDCC is decreased by the introduction of WCBP, which provides an environmentally friendly solution for the C&D and cement industries.
- Utilization of CO2 in direct aqueous carbonation of concrete fines generated from aggregate recycling: Influences of the solid–liquid ratio and CO2 concentration
Journal of Cleaner Production, Volume 312, 20 August 2021, 127832
Development of an effective aggregate recycling process for concrete waste is an important issue. During aggregate recycling, the hydrated cement fraction in concrete that decreases the quality of recycled aggregate is removed, and this yields concrete fines as a by-product. Appropriate treatment of the concrete fines is needed to improve the feasibility of aggregate recycling. In this study, concrete fines from aggregate recycling were used for CO2 utilization through direct aqueous carbonation with a low energy input using low-purity CO2 at atmospheric pressure. Two samples of actual concrete fines and one of synthetic concrete fines were compared in these experiments. The differences between CO2 uptake efficiencies were explained according to the characteristics of the different concrete fines. Solid–liquid ratio and concentration of introduced CO2 were studied and their effects on the reaction were determined and explained according to the three main steps of direct aqueous carbonation, Ca extraction, CO2 dissolution, and CaCO3 precipitation. The results are supported by and compared to the literature based on the carbonation mechanism and kinetics. Additionally, the mechanisms of particle collision and solidification were observed, and their effect was determined by several characterization analyses. The CO2 uptake efficiency was compared with those from other studies, which proves concrete fines are a promising candidate for direct aqueous carbonation. The present method under atmospheric pressure with a low CO2 concentration was effective for CO2 utilization with concrete fines and had a CO2 uptake capacity of 0.13 g-CO2/g-concrete fines.
- Green fabrication of mechanically stable superhydrophobic concrete with anti-corrosion property
Journal of Cleaner Production, Volume 312, 20 August 2021, 127836
Anti-corrosion of concrete widely used in marine structural engineering is an important issue in the study of preventing the penetration of seawater to concrete that may lead to damage of concrete structures and corrosion of internal steel bars. Superhydrophobic concrete with anti-corrosion property is a potential candidate for mitigating marine corrosion. Environmental friendliness and mechanical stability are important factors to be considered in the application of superhydrophobic concrete. Here, a green method is proposed to fabricate superhydrophobic concrete using nontoxic modified sands and sandpapers polishing. Sands modified with stearic acid provided low surface energy, while sandpapers polishing supplied rough structures for superhydrophobic concrete. The as-fabricated concrete showed superhydrophobic property with a water contact angle of ~153.7° and a water sliding angle of ~4°. Mechanical polishing test was performed on the as-fabricated concrete, which showed a robust mechanical stability. To illustrate the anti-corrosion property, electrochemical test and long-term soaking test in 3.5 wt% NaCl solution were carried out. The compressive strength and flexural strength of the ordinary concrete and the as-fabricated concrete at different ages were compared. The as-fabricated concrete with mechanical stability and anti-corrosion property is expected to be applied in marine structural engineering for anti-corrosion.
- Sewage treatment sludge biochar activated blast furnace slag as a low carbon binder for soft soil stabilisation
Journal of Cleaner Production, Volume 311, 15 August 2021, 127553
Portland cement forms the basis of most binders used in deep dry soil mixing, significantly improving the shear strength and compressibility properties of soils. However, due to the high environmental and socio-economic impacts of cement production, there is great interest in developing alternative low-carbon binders for soil stabilisation. One of the most desirable routes involves the use of industrial by-products, such as ground granulated blast furnace slag, whose pozzolanic properties require activation by alkali agents. This paper assesses the feasibility of using sewage treatment sludge biochar as a low-carbon 100% waste-based alternative to traditional alkali agents. Two biochar:slag ratios (0.5:0.5 and 0.67:0.33) were added to an artificial soil at dosages of 7.5 and 10% by dry weight and cured for up to 56 days. The engineering performance of these stabilised soil mixtures was assessed by performing a suite of compressive strength, pH, water content, mineralogical and microstructural analyses. Results were compared with those of untreated and CEM-II stabilised alluvium, along with data published in the literature. Biochar was observed to successfully activate the pozzolanic properties of the slag, whereby the studied mixtures resulted in 28-day strengths that met European soil stabilisation standards requirements. Binder mixtures with higher biochar concentrations achieved greater strengths. The best performing mixture had a biochar-slag ratio of 0.67:0.33 and dosage of 10%, which produced strengths up to 1243 kPa. This study suggests that the biochar-slag binder has encouraging prospects for replacing Portland cements in soil stabilisation, reducing the carbon footprint of the construction sector and improving the circular economy.
- Approaches to achieve fluidity retention in low-carbon calcined clay blended cements
Journal of Cleaner Production, Volume 311, 15 August 2021, 127770
High meta kaolin content (e.g. 50 wt%) present in a calcined clay blended into a composite cement is positive with respect to early strength development, but significantly decreases the dispersing effectiveness of PCE superplasticizers. Moreover, it has been observed that for such cements, slump retention is much more difficult to achieve than in OPC or other composite cements. In this study, several approaches to achieve extended workability times in mortars prepared from composite cements holding 20–40 wt % of a calcined clay were investigated. First, it was found that the slump retaining performance of a common industrial ready-mix type HPEG PCE rapidly decreased when the portion of calcined clay was increased in the blended cement. Furthermore, a combination of the ready-mix HPEG PCE and a retarder (sodium gluconate) which is commonly applied in ready-mix concrete also could not much improve fluidity retention, thus highlighting the difficulty of slump retention for such cements. To solve this problem, a new admixture formulation is introduced based on a combination of a precast type HPEG PCE and a novel PCE-LDH nanocomposite. This approach to improve slump retention was tested on composite cements holding 20–40 wt % of a calcined clay high in meta kaolin content. Mortar tests revealed that the high water-reducing (precast) type HPEG PCE and the PCE-LDH nanocomposite work synergistically and can achieve a significant improvement in fluidity retention of such calcined clay blended cements. A mechanistic investigation revealed that the PCE which was intercalated in between the [Ca2Al(OH)6]+ main layers of the PCE-LDH nanocomposite is released gradually from the mixed metal hydroxide via anionic exchange with sulfate anions present in the pore solution. This way, an extended workability time was achieved in the mortar.
- Characteristics of ferrochrome slag aggregate and its uses as a green material in concrete – A review
Construction and Building Materials, Volume 294, 2 August 2021, 123552
Industrial wastes and by-products have been explored for many years as green construction materials. The use of some industrial wastes and by-products including ground granulated blast furnace slag, silica fume, and fly ash has already been standardized in several codes of practice as green construction materials. However, Ferrochrome slag (FCS) is one of the by-products that has not yet been standardized, particularly in concrete production. FCS is produced during the extraction of ferrochrome (FC) from the natural minerals. Due to its chemical composition, physical nature, and mechanical properties, FCS has recently attracted the researchers’ interest as an alternative green and sustainable construction material, particularly as a concrete aggregate. The review article summarizes the physical, chemical, and mechanical characteristics of FCS. The review also explores the beneficial utilization of FCS as a fine and coarse aggregate in the production of green and sustainable concrete. It is found that the physical and mechanical characteristics of the FCS aggregate are generally superior to the conventional aggregate. Although FCS aggregate contains a considerable amount of the hazardous element (i.e., residual chromium), it is substantially stable within the concrete mixture. Previous studies show that FCS coarse aggregate has a considerable effect on improving the strength and durability properties of concrete. However, the contradictory effects of using FCS fine aggregate on concrete properties were observed in different studies. Subsequently, more studies are needed to observe the effect of FCS fine aggregate on the mechanical and durability properties of concrete. In addition, the long-term safety and environmental compatibility of FCS containing concrete in diversified environmental conditions should critically be assessed in the near future.
- A review on microwave irradiation to the properties of geopolymers: Mechanisms and challenges
Construction and Building Materials, Volume 294, 2 August 2021, 123491
Geopolymer has been demonstrated as a promising candidate to replace Portland cement with less carbon footprint and energy consumption. The practical application of geopolymers is largely relying on strength development via the geopolymerization process. The application of microwave (MW) as an efficient auxiliary processing technology for geopolymers manufacture is emerging. Here in this paper, the fundamental mechanisms, influencing factors, and the potentials of microwave in geopolymer applications were reviewed. The capability of volumetric heating could generate significantly different heating patterns from traditional heating, therefore greatly reducing the processing time and enhancing the mechanical strength. The selective heating of certain ingredients with different dielectric properties would also benefit the immobilization of heavy metals in the geopolymer network, therefore facilitate solid waste disposal and recycle with significant environmental benefit. The current development of the promising microwave-assisted geopolymer strategy is mainly limited by the lack of large-scale microwave reactors. Future efforts to increase the energy conversion efficiency and processing capacity of MW reactors are critical before large-scale industrial applications.
- The role of graphene in anti-corrosion coatings: A review
Construction and Building Materials, Volume 294, 2 August 2021, 123613
Graphene has attracted considerable attention as anti-corrosion material due to its peculiar two-dimensional nanostructure and superior physicochemical properties. Graphene nanosheets can be independently or concertedly applied as the barriers against metal corrosion in the form of thin films, layered structures, or composites. Numerous attempts have been made to establish the correlation between the nanoscale structure and macroscale performance of graphene. In that regard, experimental and computational methods, such as quantum chemistry and molecular simulation, allow one to gain insight into the anti-corrosion mechanisms of graphene-related coatings. This review summarizes up-to-date knowledge about pure graphene and graphene-based composite coatings, including cathodic protection and self-healing coatings. Particular attention is paid to the structure–property relationship and anti-corrosion mechanisms in these systems. Finally, the shared and distinct role of graphene in various coatings and their prospects for future research are discussed as well.
- A review on the tensile behavior of fiber-reinforced polymer composites under varying strain rates and temperatures
Construction and Building Materials, Volume 294, 2 August 2021, 123565
The fiber-reinforced polymer (FRP) composites are currently widely used in infrastructure construction, and the study on the dynamic performance and temperature sensitivity is still under investigation. Understanding the effects of strain rate and temperature on the tensile behaviour of FRP composites is vital to design the composite structures under harsh conditions (earthquake, explosion, or impact). Therefore, this study comprehensively reviews tensile performance of FRP composites under several strain rates (quasi-static, low, intermediate, and high) and temperatures. The tensile strength of FRP composites depends on the strain rates, temperatures, and coupling effect. The failure patterns of FRP materials are also reviewed at different strain rates and temperatures and found that fiber cracking and fiber pullout become dominant at low and high strain rates, respectively, which can help gain insight into failure mechanisums of FRP composites.
- A review of phase structure of SBS modified asphalt: Affecting factors, analytical methods, phase models and improvements
Construction and Building Materials, Volume 294, 2 August 2021, 123610
SBS modified asphalt (SBSMA) is widely used in asphalt pavement, but due to the characteristics of the materials and the effects of the environment and construction, the phase structure of SBSMA often undergoes adverse changes. This article reviewes the effects of SBS type and dosage, asphalt type, processing technology and environment on phase structure and separation. The correlation between the phase structure of SBSMA and chemical composition, micromechanics, rheological properties, and other aspects are analyzed. In addition, the phase structure analysis parameters of 2D image processing based on fluorescence microscope, phase field method model, and phase prediction model are generalized. Finally, the article summarizes the phase structure stability of SBSMA mixed with various materials, which provides a reference for researchers to understand the research progress in this field.
- Effects of different composite mineral admixtures on the early hydration and long-term properties of cement-based materials: A comparative study
Construction and Building Materials, Volume 294, 2 August 2021, 123547
The exploration of sustainable and green cement-based materials prepared from industrial solid wastes is an important research direction in the development of new building materials. This paper carried out a quantitative comparative study of the influences of different composite mineral admixtures prepared with fly ash, steel slag, and ground granulated blast furnace slag (GBFS) as supplementary cementitious materials (SCMs) on the early hydration, long-term (360 d and 720 d) mechanical properties and penetrability of cement-based systems. The results show that adding GBFS and steel slag has the greatest influence on the early hydration of cement due to their synergistic reactions. Over time, it becomes increasingly apparent that adding composite admixtures containing GBFS and fly ash can refine the long-term pore structure, reduce the brittleness, improve the long-term strength and chloride ion penetrability resistance of concrete to the greatest extent. However, adding composite admixtures containing steel slag and fly ash has no positive impact on the long-term properties of concrete. From a comprehensive perspective, considering early hydration, long-term properties and economic costs, composite admixtures containing GBFS and steel slag have potential for wide popularization and applications which can promote the sustainable utilization of steel slag and cleaner production of green concrete.
- Effects of coarse aggregate surface morphology on aggregate-mortar interface strength and mechanical properties of concrete
Construction and Building Materials, Volume 294, 2 August 2021, 123515
Coarse aggregate surface textures have a significant effect on mechanical properties of aggregate-mortar interface in normal strength concrete. The authors used a scanning microscope to scan the surface of aggregates in concrete to observe surface morphology. The results showed that the surface morphology components of coarse aggregates were varying at different scanning scales, which included waviness and roughness. Each component was quantitatively characterized. New methods to calculate the interfacial tensile strength and shear strength considering the influence of 3D surface morphology were proposed. The methods were introduced into a 3D meso-numerical model. Uniaxial compression and direct tension tests were conducted to examine the effects of coarse aggregate surface morphology (CASM) on the mechanical behaviors of concrete. Compared to the test results, the numerical model can well predict the failure procedure of concrete and the cracking characteristics of interface with different aggregate surface morphologies. Moreover, it was found that concrete tensile strength was more sensitive to CASM than compressive strength.