17/08/2021

Công bố quốc tế trong lĩnh vực kiến trúc, xây dựng (Tuần 2 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:

– Ứng dụng chiến lược sinh thái môi trường trong quy hoạch kiến ​​trúc không gian thành phố thông minh.

– Quy hoạch đô thị và chất lượng cuộc sống: đánh giá các liên kết giữa môi trường được xây dựng với đời sống hạnh phúc.

– Các yếu tố ảnh hưởng của khu dân cư không gian mở thân thiện với người lớn tuổi trong bối cảnh nhà ở cao tầng mật độ cao trong thời tiết nắng nóng: Một nghiên cứu điển hình về nhà ở công cộng ở Hồng Kông.

– Đô thị hóa, cơ sở hạ tầng giao thông, CNTT-TT và tăng trưởng kinh tế: Phân tích nguyên nhân và hệ quả trước mắt.

– Khả năng tưởng tượng về địa điểm, cảm giác về địa điểm và điều hướng không gian: điều tra cộng đồng.

– Thành phố thông minh sẽ nâng cao tính cộng đồng trong xã hội? Tầm quan trọng của quản lý khu phố thông minh.

– Quản lý không gian mở đô thị ở các nước Bắc Âu: xác định các thách thức hiện tại dựa trên nhận thức của nhà quản lý.

– Khuôn khổ đánh giá tác động của sự phụ thuộc vào lối mòn đối với các kết quả quy hoạch đô thị, được tạo ra thông qua việc sử dụng các công cụ hỗ trợ ra quyết định.

– Quy hoạch không gian tương tác của cơ sở hạ tầng xanh đô thị – Trang bị thêm những mái nhà xanh nơi các dịch vụ hệ sinh thái cần thiết nhất ở Oslo.

– Phân tích cảm xúc tác động đến quy hoạch đô thị trong không gian công cộng.

Khoa học và công nghệ trong lĩnh vực kiến trúc, xây dựng:

– Mô hình giàn làm mềm hiệu quả cho các phần tử màng bê tông sợi thép dự ứng lực.

– Tăng cường truyền nhiệt trong môi trường trao đổi nhiệt của cọc năng lượng.

– Các tòa nhà CLT chống động đất được làm cứng bằng các thanh thép dọc.

– Ứng dụng song sinh kỹ thuật số trong ngành xây dựng: Tổng quan tài liệu.

– Nghiên cứu đặc tính và bề mặt kỵ nước của phụ gia TiO2, ZnO và cacbon tái chế gốc silic trên bề mặt vật liệu kết dính.

– Tăng cường độ cứng bề mặt của composite bê tông ngậm nước bằng dung dịch nước stronti nitrat (Sr (NO3) 2)

– Hệ thống vận thăng xây dựng tự động dựa trên học sâu được tăng cường trong xây dựng nhà cao tầng.

– Đánh giá sự thay đổi của cấp phối hỗn hợp bê tông nhựa trong thi công mặt đường bê tông nhựa.

– Tận dụng các mặt tích hợp để có khả năng tương tác với công cụ dựa trên mô hình.

– Sử dụng học sâu, phân tích kỹ thuật và tương quan chéo để dự đoán áp suất bùn của máy khiên trong điều kiện đất nền hỗn hợp.

Vật liệu xây dựng:

– Vật liệu điều chỉnh độ ẩm thông minh được tổng hợp thủy nhiệt từ chất thải gốm sứ.

– Phát triển các chỉ số hiệu quả sinh thái composite mới cho bê tông.

– Xử lý chất thải gỗ để sử dụng làm chất hấp phụ kim loại nặng như các thành phần của gạch xây dựng.

– Đề xuất các mô hình triển khai để xác định cường độ nén, kéo và uốn của bê tông cốt liệu thô tái chế thông qua thuật toán.

– Đánh giá phản ứng các vật liệu kết dính nền magie: Sự phát triển hiện tại và tiềm năng ứng dụng.

– Xác định định lượng chất thải đã qua xử lý mở rộng hiệu suất đá perlite như một vật liệu kết dính bổ sung trong vật liệu tổng hợp xi măng trộn phát thải thấp.

– Kết quả từ việc cháy tấm thạch cao có cốt liệu sợi cáp nhựa.

– Mô hình hóa sự truyền nhiệt và độ ẩm của mặt tiền tòa nhà được cách nhiệt bằng các tấm có các kênh thông gió.

– Cơ chế truyền nhiệt của bê tông cách nhiệt hạt rỗng tráng men.

– Thử nghiệm nén dọc trục trên ống thép cường độ cao hình elip đổ đầy bê tông tự lèn với các tỷ lệ cấp phối khác nhau.

Xin trân trọng giới thiệu!

QUY HOẠCH ĐÔ THỊ

1. Application of environmental ecological strategy in smart city space architecture planning

       Environmental Technology & Innovation, Volume 23, August 2021, 101684

       Abstract

A smart city requires the organic integration of a good ecological environment with people’s healthy life, so that the city can achieve the purpose of economic construction and ecological environmental protection. In this case, the spatial layout of a smart city must be based on the ecological environment. Under the guidance of the concept of ecological protection, the ecological space of smart cities is not only green space and parks. At the same time, the building communities in the city and the construction land in the city should be green and environmentally friendly. These situations require planning and design in the spatial design layout through networking and informatization. This article mainly studies the space development of smart cities under the integration of information technology and ecological environment from the perspective of urban space architectural planning. A series of problems in our country’s cities and the close connection between smart cities and the ecological environment. After comprehensively analyzing the smart city spatial planning of different cities and regions under the influence of the ecological environment, it tries to analyze the guiding role and development direction of the smart city spatial architectural layout planning under the ecological environment.

2. Can public subsidized urban renewal solve the gentrification issue? Dissecting the Viennese example

Cities, Volume 115, August 2021, 103218

Abstract

The paper focuses on the effects of publicly subsidized urban renewal projects by unraveling the mechanism in force affecting the social sustainability of these projects in Vienna.

The goal of Vienna’s model of ‘gentle urban renewal’ has been and still is not to force out the resident population, but rather to renovate the old buildings in a way that the apartments remain affordable for their tenants after renovation by subsidizing the renewal of apartment buildings. The main instruments of this renewal policy, its results, and challenges will be presented in this paper, analyzed and dissected by empirical research.

The social sustainability of Vienna’s model of subsidized urban renewal is tested by indicators like rents of apartments, quality of apartments and household incomes of tenants before and after renewal by applying non-parametric statistics. Based on the notions of Lees (2015) on state-led renewal the analysis of the Vienna case provides an original contribution to the discussion on public policy-led renewal and its effects on gentrification and displacement. The analysis of the outcomes of the initiative implies that the gentle urban renewal program itself does not avoid some phenomena of gentrification but does not result in a radical displacement of residents.

  1. Urban planning and quality of life: A review of pathways linking the built environment to subjective well-being

Cities, Volume 115, August 2021, 103229

Abstract

In light of the rapid global urbanization, providing a better quality of life in cities is becoming an increasingly critical issue for urban planning. However, the links between the built environment and subjective well-being are not sufficiently understood. This paper reviews the evidence on the range of pathways linking the built environment to subjective well-being. Seven potential pathways are identified and reviewed: (1) travel, (2) leisure, (3) work, (4) social relationships, (5) residential well-being, (6) emotional responses, and (7) health. Based on this knowledge, the paper presents an overview of strategies for improving subjective well-being through urban planning. Among others, proposed strategies are to: enhance conditions for active travel; improve public transport while restricting cars; provide easy access to facilities and services; develop or steer technology and emerging mobility options to improve inclusiveness and quality of life for different groups; integrate various forms of urban nature as much as possible; provide accessible, inclusive public spaces and communal spaces; maintain upkeep and order in urban space, vegetation, and transport systems; implement noise reduction strategies; develop aesthetically pleasing buildings and public spaces based on residents’ needs and preferences; and reduce socio-spatial inequalities while providing support for housing and transport for vulnerable groups.

  1. Influential factors of age-friendly neighborhood open space under high-density high-rise housing context in hot weather: A case study of public housing in Hong Kong

Cities, Volume 115, August 2021, 103231

Abstract

The growing elderly population living in high density cities undergoing mass urbanization raises concerns over age-friendliness of neighborhood open space, an essential component for healthy aging-in-place as elderly tend to spend most of their time at home and immediate home environment. This study discusses factors that influence age-friendly open space design pertaining to outdoor thermal environment and physical design element for high-density high-rise housing in hot weather, using the case of public housing developments in Hong Kong. Field measurements, observations and linear regression data analyses are used to understand dynamic thermal condition, adaptive elderly user behavior and response to planned open space. It is demonstrated that four influential factors are important to correlate with elderly residents’ use of open space: 1) mean radiant temperature (MRT); 2) air temperature; 3) greenery; and 4) outdoor seating. Moreover, it is found that MRT, specifically long-wave MRT, is the most influential and impacts the effectiveness of greenery and outdoor seating. In addition, the study proposes guide points to reflect the effect of each factor and shed more insight into improving age-friendly neighborhood open space design against climate-change induced heat-related health issues.

  1. Transit development and housing displacement: The case of the Chicago Red Line Extension

Cities, Volume 115, August 2021, 103212

Abstract

Chicago’s South Side has long been characterized as a “transit desert” – an area with high transit inaccessibility and insufficient infrastructure to meet residents’ needs (Jiao & Dillivan, 2013). Without adequate transit, residents cannot reach employment opportunities or regional amenities – contributing to economic, spatial, and social marginalization. The Chicago Transit Authority’s proposed Red Line Extension (RLE) is designed to connect the city’s far south side neighborhoods to Chicago’s core. Given the scope of the RLE, 175 parcels have been chosen for demolition, meaning that a similar number of households face displacement to make room for the RLE right of way – which may have potentially negative consequences in realizing the subsequent benefits of improved transit access. In this article, we perform an ex-ante analysis of RLE induced displacement. Specifically, we: 1) predict potential location choices that transit displacees are most likely to choose; and 2) analyze these locations in relation to access to transit, amenities, employment, and housing affordability, among others. Within the context of transportation planning, ex-ante analysis is important because it can minimize unintended and negative consequences of transit-induced displacement – like decreased transit access and a loss of potential neighborhood improvements – by predicting potential relocation choices for displacees. Such predicted choices can help planners and decision-makers better understand the trade-offs for directly affected households and thereby allow planners and decision-makers to assist in relocation assistance that maximizes the benefits of the necessarily displaced.

  1. Urbanization, transportation infrastructure, ICT, and economic growth: A temporal causal analysis

Cities, Volume 115, August 2021, 103213

Abstract

In many countries, urbanization is seen as an important policy tool to ensure sustained economic growth. While urbanization can lead to positive economic outcomes, unfettered migration into urban areas without appropriate infrastructure support such as information and communication technology (ICT) infrastructure and transportation infrastructure can lead to negative side effects such as congestion, formation of slums, and other diseconomies of scale. The latter can actually lower economic growth. This study examines the relationships between urbanization, transportation infrastructure, ICT infrastructure, and economic growth in the G-20 countries from 1961 to 2016. Using the panel vector error-correction model, the study shows that there is a myriad of temporal causal relationships between the four variables in both the short and long run. The key policy implication of these results is that long-run economic growth in the G-20 countries depends on the co-development of policies in creating a vibrant urban ecosystem that is enabled by intelligent transportation systems and underpinned by a sound ICT infrastructure plan.

  1. A census tract level analysis of urban sprawl’s effects on economic mobility in the United States

Cities, Volume 115, August 2021, 103232

Abstract

Researchers highlight the importance of urban form and sprawling development patterns as determinants of economic mobility in the United States. However, the relationship is complex because sprawl affects other variables too, which themselves may affect upward mobility. This study uses a structural equation model to estimate the direct and indirect effects of urban sprawl, and related components of the built environment, on mobility at the census tract level. The results suggest that compactness has a positive direct effect on mobility, but an overall negative indirect effect on mobility through the tested mediating factors. Hence, there are both positive and negative side-effects associated with compactness in regards to economic mobility. In light of these findings, this paper recommends policies, programs, and procedures for the planning community to aid in alleviating the negative consequences of sprawl on economic mobility, while maintaining the positive ones.

  1. Place imageability, sense of place, and spatial navigation: A community investigation

Cities, Volume 115, August 2021, 103245

Abstract

How do spatial navigation and place imageability illuminate our understanding of sense of place in urban neighborhoods? Rather than rely on their place memories, the present study asked community residents to think about their neighborhood in situ. A stronger sense of place was experienced for areas of their neighborhood with greater place imageability. The residents employed more allocentric spatial navigation strategies when they mentally navigated areas that differed in place imageability compared to egocentric strategies. As predicted, paths and edges were noted more often while residents mentally navigated areas with greater or moderate place imageability than lesser place imageability. Meaningful associations were found between sense of place, allocentric strategy use, and the length of time participants had experienced different areas of the neighborhood. Social scientists and city planners may benefit from these results as they consider local place imageability in relation to residents’ typical navigation strategies and attachment to their urban communities.

  1. Return migration and in situ urbanization of migrant sending areas: Insights from a survey of seven provinces in China

Cities, Volume 115, August 2021, 103242

Abstract

Based on a survey in seven provinces and drawing on previous evidence of in situ urbanization in the coastal areas, this paper examines the implications of return migration for in situ urbanization of migrants’ sending areas in China. It shows that returnees can act as catalysts for in situ urbanization by bringing back entrepreneurship, accrued human, financial, social, cultural and technological capital to facilitate rural-urban socioeconomic transformation of their home areas. The results of logistic regressions further confirm that returnees’ individual characteristics and migration occupations significantly increase their probability of engaging in non-agricultural occupations post return. However, they seem to have little impact on returnees’ likelihood of working in local urban areas. The results suggest that even though return migrants have exhibited somewhat positive impacts on the development of their home areas, their role is rather limited in promoting in situ rural-urban transformation. A weak industrial base at the origin has been identified as a major barrier for rural-urban transformation, which suggests that strategic measures to strengthen industrial capacity in those migrant sending areas should take place in order to fully unleash return migrants’ potential in stimulating in situ urbanization of their home areas.

  1. Will smart cities enhance the social capital of residents? The importance of smart neighborhood management

Cities, Volume 115, August 2021, 103244

Abstract

Social capital is a concept that indicates the strength of the relationship among people inside and outside a community. It is a factor that facilitates policy for community formation and regeneration and is also an indicator of the outcome of a policy for improving a community. This study examined the hypothesis that the regional efforts to create smart cities using advanced ICT technologies enhance the social capital of the city and identified the factors that enhance social capital. Urban policy in Japan is shifting from hardware-oriented development to software-oriented area management; the Minato Mirai 21 district in the city of Yokohama is a typical example of area management. The essence of smart transition is to enhance various management functions by using smart social technologies, such as advanced information communication. The attractiveness of smart cities with sophisticated area management provided by such technologies will likely be high. Thus, this study’s results will provide useful implications for better area management in smart cities.

  1. Urban open space management in the Nordic countries. Identification of current challenges based on managers’ perceptions

Cities, Volume 115, August 2021, 103225

Abstract

This paper reports on how Nordic practise relates to, and perceives contemporary challenges to urban open space management. The study used a case study approach, via interviews. The studied Nordic cities experience the effects of densification in inner city areas. This is often resulting in higher pressure on existing urban open spaces, but also generating new spaces which tend to be small and fragmented, not meeting the many wishes and demands asked for by the diverse user groups. While budgets are sufficiently allocated in new development projects, it is a challenge to withstand the maintenance budgets, forcing managers to prioritise. Due to primary political interest in inner city areas, there is a risk of managers not prioritising the more peripheral areas, from where resources are often transferred to the newly developed areas. This creates a new type of urban nature, primarily in the urban peripheral areas, with increased amounts of biodiversity and higher amounts of multi-functionality, compared to the smaller and more intensively programmed inner-city areas. Urban open space managers are relying on the existing municipal planning tools, and to varying degrees act strategically in terms of developing own sector oriented plans and strategies.

  1. A framework to assess impacts of path dependence on urban planning outcomes, induced through the use of decision-support tools

Cities, Volume 115, August 2021, 103256

Abstract

Urban planning stakeholders can use decision-support tools (DST) to foster transformation towards sustainable urban morphologies. This paper proposes an analytical framework to support urban planning practitioners in assessing how the use of DST might impact planning outcomes due to path dependence. We identify five key dimensions of path dependence in a spatial socio-technical system as analytical framework to assess the influence of DST on planning outcomes. Potential impacts on urban planning outcomes are analysed by applying the proposed framework to a particular spatial socio-technical system, namely New Zealand’s use of DST to support urban planning decision-making towards sustainable urban morphologies. The assessment framework and comparative case study analysis illustrate how the interaction between planning culture and some DST features can influence decisions pertaining to urban morphologies and raise awareness about DST-induced path dependence.

  1. Examining the associations between perceived built environment and active travel, before and after the COVID-19 outbreak in Shiraz city, Iran

Cities, Volume 115, August 2021, 103255

Abstract

This study aims to evaluate the effects of the COVID-19 pandemic and policies to control the outbreak such as quarantine, jobs closures, and traffic restrictions on active travel of Central Businesses District (CBD) residents in comparison with the non-CBD residents of Shiraz, Iran; and examine the relationship between perceived built environment factors and active travel in the pre- and post-outbreak. The results indicate that the most effective individuals factors on active travel are bicycle and car ownership, and built environment characteristics are walkability, bikeability, security, aesthetics, traffic calming, intersections safety, land uses diversity and density, destination accessibility, street pattern, and bike-sharing infrastructures. Also, the average walking and cycling time of the CBD residents before and after the outbreak is more than that of the non-CBD residents, which is due to the quality of built environment factors in the CBD. A built environment with mixed, diverse, dense and accessible land uses, as well as safe and secure cycling and walking routes have major effects on active travel in the crisis. Hence, it is suggested that policymakers take action to make the environment more people-friendly to maintain citizens’ mobility in the critical situation, when many travel modes have lost their efficiency.

  1. Interactive spatial planning of urban green infrastructure – Retrofitting green roofs where ecosystem services are most needed in Oslo

Ecosystem Services, Volume 50, August 2021, 101314

Abstract

Spatial multi-criteria decision analysis (MCDA) is increasingly being used to inform urban green infrastructure planning. We explore the use of modern cloud computing technologies (Google Earth Engine) to facilitate public access to spatial MCDA of ecosystem services from green infrastructure. Using the spatial prioritization of green roof retrofitting in Oslo, Norway, as a case study, we present a web application that is a generalizable tool for engaging stakeholders in spatial planning of ecosystem restoration and nature-based solutions. In our application, green roof designers, owners and operators identified the relative importance of a suite of potential ecosystem services (ES) gained from retrofitting of green roofs, conditional on preference profiles expected by users of different building functional types. The ES assessed included temperature regulation, stormwater runoff mitigation, habitat for biodiversity, aesthetic value, and noise reduction. In Oslo we found high spatial correlation in ES deficits, implying that even large differences in stakeholder preferences for individual ES will lead MCDA to identify common interests in the spatial targeting of green roofs. Nevertheless, we found the interactive spatial MCDA web application to have potential for improving planning process efficiency in engaging stakeholders. In more heterogenous urban landscapes, with lower spatial correlation of individual ES, spatial MCDA also has scope to improve the output efficiency of spatial targeting of nature-based solutions such as green roofs. Link to web application: https://nina.earthengine.app/view/green-roof-mcda.

  1. Emotions analysis in public spaces for urban planning

Land Use Policy, Volume 107, August 2021, 105458

Abstract

Scientists have been attempting to apply emotions in the urban planning process with qualitative methods (surveys, interviews, questionnaires and the like) since the mid-1900s. However, at that time, there were no possibilities for applying biometric or other kinds of tracking and remote technologies to detect and recognize the emotions felt by other people. The 21st century brought forth such opportunities. Nonetheless, even currently, the remotely integrated, emotional, affective and physiological states, arousal and valence (MAPS) of individuals residing or visiting urban areas are very seldom analysed. Meanwhile stakeholder groups are unable to receive digital advice with a goal to upgrade urban areas to be more pleasant, comfortable and sustainable. In such a context, the authors of this study developed an Affective System for Researching Emotions in Public Spaces for Urban Planning (ASP System). This System has added to the body of knowledge on research in several ways. ASP can prove a helpful supplement to urban planning and public participation practice by gathering and analysing MAPS data of passersby, weather conditions, pollution and other data. This unique combination of MAPS data can assist city stakeholders in initiating effective planning solutions based on an inhabitant-centric method. Additionally ASP employs a neuro decision matrix, which assisted in deriving a comprehensive analysis of the urban areas under deliberation by MAPS parameters. This article also submits eight avenues of practical use for urban planners when employing MAPS data and the ASP Method and System. The case studies on cultural heritage sustainability confirm the accuracy of the developed ASP Method and System.

  1. Emotions analysis in public spaces for urban planning

Land Use Policy, Volume 107, August 2021, 105458

Abstract

Scientists have been attempting to apply emotions in the urban planning process with qualitative methods (surveys, interviews, questionnaires and the like) since the mid-1900s. However, at that time, there were no possibilities for applying biometric or other kinds of tracking and remote technologies to detect and recognize the emotions felt by other people. The 21st century brought forth such opportunities. Nonetheless, even currently, the remotely integrated, emotional, affective and physiological states, arousal and valence (MAPS) of individuals residing or visiting urban areas are very seldom analysed. Meanwhile stakeholder groups are unable to receive digital advice with a goal to upgrade urban areas to be more pleasant, comfortable and sustainable. In such a context, the authors of this study developed an Affective System for Researching Emotions in Public Spaces for Urban Planning (ASP System). This System has added to the body of knowledge on research in several ways. ASP can prove a helpful supplement to urban planning and public participation practice by gathering and analysing MAPS data of passersby, weather conditions, pollution and other data. This unique combination of MAPS data can assist city stakeholders in initiating effective planning solutions based on an inhabitant-centric method. Additionally ASP employs a neuro decision matrix, which assisted in deriving a comprehensive analysis of the urban areas under deliberation by MAPS parameters. This article also submits eight avenues of practical use for urban planners when employing MAPS data and the ASP Method and System. The case studies on cultural heritage sustainability confirm the accuracy of the developed ASP Method and System.

  1. 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

Abstract

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.

  1. From the ground up: Using structured community engagement to identify objectives for urban green infrastructure planning

Urban Forestry & Urban Greening,Volume 59, April 2021, 127013

Abstract

Municipal governments are increasingly looking to green infrastructure to address climate-related flooding and water quality issues, and as a cost-effective way to augment aging ‘grey’ stormwater infrastructure. There is also a great deal of interest in more fully involving citizens in efforts to increase the amount of green infrastructure in cities. Despite this acknowledgement of the importance of public engagement, however, many green infrastructure initiatives still adhere to a top-down and expert-driven process of site selection and design. This mismatch between process and engagement ideals can lead to suboptimal outcomes in terms of sustaining these projects over the long term, the achievement of multifunctional and inclusive spaces, and missed opportunities to increase civic capacity to participate in and drive urban planning initiatives. Further, the turn to green infrastructure has been criticized for not including a diversity voices in planning, design and implementation, with green gentrification occurring as a result. Thus, the objectives of this research were to, in collaboration with communities, (i) use structured elicitation to establish social and ecological priorities (in the form of key ecosystem services and disservices) to inform a community-based GI design and planning process, and (ii) use this collaboration to inform the development of the Land.Info DSS that creates realistic representations of site scale landscape change and incorporates community identified priorities as real-time feedback. Community members reported that including their design objectives in the Land.Info design tool helped to guide their green infrastructure designs and that they modified their designs in response to the feedback provided within the interface. Additional desired outcomes of this research were to provide a vehicle for improved public engagement and learning opportunities for GI planning, design and implementation, and to develop a reliable and scalable method for incorporating community values and needs into these processes. Providing residents with meaningful opportunities for input and collaboration in urban landscape planning and design aligns with the growing interest in democratizing the design, management, and governance of public spaces.

  1. Improving methods to calculate the loss of ecosystem services provided by urban trees using LiDAR and aerial orthophotos

Urban Forestry & Urban Greening, Volume 63, August 2021, 127195

Abstract

In this paper we propose a methodology for combining remotely sensed data with field measurements to assess selected tree parameters (diameter at breast height (DBH) and tree species) required by the i-Tree Eco model to estimate ecosystem services (ES) provided by urban trees. We determined values of ES provided by trees in 2017 in Racibórz (a city in South Poland) and estimated the loss of ES from January 1, 2017 to March 5, 2017, a period of changing legislation that temporarily allowed removal of trees on private property without any permission from city authorities. We applied Canopy Height Models (CHM; GSD 1.0 m) generated from two sets of ALS LiDAR point clouds (acquisitions on June 11, 2011 and March 5, 2017) and performed tree crown segmentations using the GEOBIA approach. Physical attributes were estimated for each tree using predictive models, developed based on field tree inventory . The reference areas for parameterizing the segmentation algorithm and assessing tree species composition were established in Racibórz, while reference data required for assessment of DBH were obtained from the MONIT-AIR project (from Municipality of Kraków). We found that in 2017, 988.79 ha of Racibórz (13.2 % of city area) was covered by the crowns of 264 471 trees, providing ES structural values worth over 384 mil €. The structural value of ES lost in the first months of 2017 (during which 5 075 trees were removed) was about 3.5 mil €. We concluded that in the face of information on tree crown cover that is often missing from city databases, tree inventories require application of a combination of multi-source and multi-resolution spatial analyses, including: administrative decisions for tree removal with exact location, predictive modelling of selected biometrical tree information, automatic crown segmentation on CHM and interpretation of regularly updated color infrared (CIR) aerial orthophotos.

  1. Gardens’ contribution to people and urban green space

Urban Forestry & Urban Greening, Volume 63, August 2021, 127198

Abstract

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.

KHOA HỌC VÀ CÔNG NGHỆ TRONG LĨNH VỰC KIẾN TRÚC, XÂY DỰNG

  1. Efficient softened truss model for prestressed steel fiber concrete membrane elements

Journal of Building Engineering, Volume 40, August 2021, 102363

Abstract

In this article, a recent version of the rotating-angle softened truss model proposed by the authors, to compute the full behavior of prestressed concrete membrane elements under in-plane stresses, is extended to prestressed steel fiber concrete membrane elements. For this, the smeared constitutive relationships for the component materials are modified to include the influence of the steel fiber reinforcement. In particular, a new smeared constitutive relationship for steel fiber concrete in tension is incorporated in the model. The extended model, called efficient rotating-angle softened truss model for prestressed steel fiber concrete, is checked against some experimental results found in the literature and related with prestressed steel fiber concrete panels tested under shear up to failure. It is shown that the proposed model is able to predict well the full behavior of prestressed steel fiber concrete membrane elements for all loading ranges, including the influence after cracking of the steel fiber reinforcement.

  1. Enhancing heat transfer in the heat exchange medium of energy piles

Journal of Building Engineering, Volume 40, August 2021, 102375

Abstract

As systems for utilizing geothermal energy, energy piles have been widely employed in many engineering applications, and they offer various advantages. A significant amount of research has been devoted toward developing methods to enhance the heat exchange efficiency of these systems, including studies on the shape of the heat exchange tube and the shape and spacing of the energy piles. After around four decades of research and development, existing methods for improving the heat exchange efficiency have become relatively mature, thus hindering further improvements. Therefore, it is essential to develop an alternative approach for enhancing the heat transfer and improving the heat exchange efficiency of these systems. To this end, this paper first summarizes the conventional heat transfer model and then elaborates on the selection of the concrete pile material as the heat transfer medium. In this study, samples of graphite concrete and silicon carbide (SiC) concrete were prepared. Subsequently, several tests on the heat transfer behaviors and mechanical performances of the samples were conducted, in order to determine the physical and mechanical properties of the modified concrete. The results showed that, at the same ambient temperature, when the graphite content exceeded 15%, the heat transfer coefficient increased, leading to a significant improvement in heat transfer. However, the compressive strength decreased noticeably. With an increase in the SiC content, the thermal conductivity of the concrete gradually increased, while the compressive strength of the concrete with SiC increased considerably. The results proved that modifying the concrete used in energy piles is a feasible method for improving heat transfer.

  1. Earthquake-resistant CLT buildings stiffened with vertical steel ties

Journal of Building Engineering, Volume 40, August 2021, 102334

Abstract

The interest in multi-storey CLT buildings in seismic areas is leading to the development of new strategies to increase the lateral stiffness of shear walls and to resist high tensile forces due to rocking. Both these purposes can be achieved with vertical steel ties placed at each shear-wall end, to directly transfer tensile forces from each storey to the foundation. Three technologies are proposed for transferring forces from CLT panels to the ties: the use of nailed plates, of screwed connectors, or directly by contact with a thick plate at the top of each storey wall. The dynamic behaviour of CLT shear walls, representing the bracing system of a building and anchored with the aforementioned technologies, has been investigated by means of dynamic analyses and a comparison with the use of common nailed plates or screwed connections without ties. Results, varying the number of storeys and the seismic mass, show that the proposed technology is an effective strategy to increase the feasibility of multi-storey CLT buildings. Complementary non-linear static analyses have been performed to evaluate the actual displacement capacity and ductility of the systems.

  1. Digital twin application in the construction industry: A literature review

Journal of Building Engineering, Volume 40, August 2021, 102726

Abstract

The construction industry is faced with numerous challenges including low productivity, lack of research and development, and poor technology advancements. Advances in digital technologies such as digital twin (DT) has seen enormous utilisations in digitally advanced industries including the manufacturing and automotive industries. It presents an opportunity for the integration of the physical world to the digital world. DT technology has the potential to transform the construction industry and provide responses to some of its challenges. As a result, the concept of DT has attracted much attention and is developing at a rapid pace. The overarching aim of this study was to analyse the current state of DT applications in the construction industry. This study comprehensively reviews and analyses DT concept, technologies, and application in the construction industry using a systematic review methodology while incorporating the science mapping method. After a complete search of several databases and careful selection in line with the proposed criteria, 22 academic publications about DT application in the construction industry were identified and classified accordingly. The research analysed in detail the status, evolution of the concept, key technologies, and six areas of application in the lifecycle phases of a project: building information modeling, structural system integrity, facilities management, monitoring, logistics processes, and energy simulation. This research shows that there is a high potential for DT to enable solutions to the numerous challenges in the construction industry. Thus, this study raises the level of awareness and need for the application of DT in the construction industry.

  1. Characterization and hydrophobic surface study of silicon-based TiO2, ZnO and recycled carbon additives on cementitious materials surface

Journal of Building Engineering, Volume 40, August 2021, 102689

Abstract

The hydrophobic properties of cementitious mortar surfaces coated with silicone-based TiO2, ZnO and recycled nano carbon black (RNCB) filled composites prepared in different proportions to protect building materials were compared. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffractometer (XRD), 3D surface profilometry, surface roughness and contact angle tests were performed to evaluate the surface performance of hydrophobic samples. The results showed that the particles were uniformly distributed over the mortar surface of the hydrophobic samples. It was determined that the amount of TiO2 and ZnO particles in the crystalline phase is an important factor in crystallite sizes and lattice strain. For the ZnO–S2 sample, the contact angle of the water droplet showed hydrophobic behavior up to 155°. However, the contact angle of the 145° RNCB-S2 sample is important for low cost hydrophobic surface work. While the highest homogeneous roughness distribution (4.33 μm) was determined on the sample surfaces in the ZnO–S sample, the closest value to the ZnO–S sample was determined in the RNCB-S sample (3.47 μm). In this study, it was tried to prevent liquid ingress from the porous structure of mortar by forming a hydrophobic coating on the mortar surface. Especially, the hydrophobic properties of RNCB particles on the cementitious material surface are thought to be important in reducing the wettability on cementitious material surfaces.

  1. Enhanced surface hardening of hydrated concrete composite by strontium nitrate (Sr(NO3)2) aqueous solution

Journal of Building Engineering, Volume 40, August 2021, 102696

Abstract

This study experimentally investigates the effects of strontium nitrate (Sr(NO3)2) aqueous solution on hardened concrete composite as a surface hardening method. Density, void content, water sorptivity, and surface abrasion resistance of the concrete mixture treated by Sr(NO3)2 solution were measured under diverse curing and treatment scenarios. The results showed that 30% Sr(NO3)2 aqueous solution increases the density by 1.0% and 2.2% and also decreases the void content by 7.4% and 14.4% with the water-cement ratio (w/c) of 0.5 and 0.4, respectively. Water sorptivity of the treated hardened concrete was decreased by 26.4% and 34.0% from the lithium silicate and sodium silicate treatments, respectively. In addition, the Sr(NO3)2 treatment increases the surface abrasion by 45% from the control specimen and about 25–30% from the two silicate-based treatments. X-ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive spectrometer (EDS), and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) were conducted to investigate the micro-morphologies, microstructure, and elemental characteristics. The results illustrate that (1) microstructures of hydrated cement matrix are densified, (2) portlandite (CH) in the matrix decreases as time elapses, (3) multiple types of hydrated aluminosilicate minerals (i.e. zeolites) are formulated, and (4) more subsequent polymerization related to C–S–H/C-A-S-H occurs. Lastly, the densifying and strengthening mechanisms of the hydrated cement by the Sr(NO3)2 treatment process are presented and discussed.

  1. Autonomous construction hoist system based on deep reinforcement learning in high-rise building construction

Automation in Construction, Volume 128, August 2021, 103737

Abstract

Construction hoists at most building construction sites are manually controlled by human operators using their intuitions; as a result, unnecessary trips are often made when multiple hoists are operating simultaneously and/or when complicated hoist calls are requested. These trips increase a passenger’s waiting time and lifting time, reducing the lifting performance of the hoists. To address this issue, the authors develop an autonomous hoist supported by a deep Q-network (DQN), a deep reinforcement learning method. The results show that the DQN algorithm can provide better control policy in complicated real-world hoist control situations than previous control algorithms, reducing the waiting time and lifting time of passengers by up to 86.7%. Such an automated hoist control system helps shorten the project schedule by increasing the lifting performance of multiple hoists at high-rise building construction sites.

  1. Variability evaluation of gradation for asphalt mixture in asphalt pavement construction

Automation in Construction, Volume 128, August 2021, 103742

Abstract

Variability of gradation for asphalt mixture is always the difficulty faced by the control of pavement construction, involving the pavement performance. The main purpose of this study is to improve the efficiency of detection for gradation variation and clarify the relationship between gradation variation and construction process. The variability of gradation for superpave asphalt mixtures was investigated with nominal maximum aggregate size (NMAS) of 13 mm, 20 mm, and 25 mm in construction. The correlation between the passing percentages at each sieve size and performance of asphalt mixture was first established by coupling grey relational analysis and entropy weight method. A digital image processing technology with multi-thresholds segmentation (DIP-MTS) was developed and verified through the experiment comparison. An approach to reversely calculate the gradation of cold aggregate was established. The mixture gradations during various construction stages were compared. Results illustrate that the passing percentages of sieves with NMAS, 4.75 mm, and 0.075 mm have a significant influence on the pavement performance and should be paid more attention during construction. The detection results of DIP-MTS are closer to the experimental value, and this technology is capable of detecting gradation for moving aggregate. The reverse calculation approach is proved feasible. Gradation variation in transportation is more severe than other construction processes.

  1. Leveraging integration facades for model-based tool interoperability

Automation in Construction, Volume 128, August 2021, 103689

Abstract

Data exchange and management methods are of paramount importance in areas as complex as the Architecture, Engineering and Construction industries and Facility Management. For example, Big Open BIM requires seamless information flow among an arbitrary number of applications. The backbone of such information flow is a robust integration, whose tasks include overcoming technological as well as semantic and pragmatic gaps and conflicts both within and between data models. In this work, we introduce a method for integrating the pragmatics at design-time and the semantics of independent applications at run-time into so-called “integration facades”. We utilize Model-driven Engineering for the automatic discovery of functionalities and data models, and for finding a user-guided consensus. We present a case study involving the domains of architecture, building physics and structural engineering for evaluating our approach in object-oriented as well as data-oriented programming environments. The results produce, for each scenario, a single integration facade that acts as a single source of truth in the data exchange process.

  1. Automatic identification of dense damage-sensitive features in civil infrastructure using sparse sensor networks

Automation in Construction, Volume 128, August 2021, 103740

Abstract

Widespread monitoring of bridges is yet rarely employed at a territorial level due to the high costs of monitoring systems. However, the aging of civil infrastructures, combined with the growing traffic demand, poses the need for a simple and automatic tool that helps emergency management. In this paper, an integrated algorithm for the identification of dynamic and dense quasi-static structural features exploiting moving vehicles is proposed. Filtering raw acceleration structural responses, triggered by passing vehicles, enables the identification of modal parameters and curvature influence lines. The procedure can be implemented efficiently as its main computational core consists of convolutions. The definition of a curvature-based damage index leads to accurate localization and quantification of structural anomalies using few sensors. The proposed procedure is tested on three viaducts of the Italian A24 motorway. Moreover, a numerical model is studied to evaluate the potentialities of the strategy for damage localization.

  1. Use of deep learning, denoising technic and cross-correlation analysis for the prediction of the shield machine slurry pressure in mixed ground conditions

Automation in Construction, Volume 128, August 2021, 103741

Abstract

Tunnel face stability constitutes a significant challenge for shield tunneling in urban areas. The use of a slurry pressure balanced shield machine in mixed ground conditions containing mudstone is generally disturbed by clogging, which results in noises and large fluctuations in the tunnel face pressure. These fluctuations add difficulties to the prediction of the slurry pressure. This paper proposes a denoising method to overcome this difficulty. This method is combined with variational mode decomposition and detrended fluctuation analysis. The method is coupled with cross-correlation analysis (CCA) and a long short-term memory (LSTM) network to predict the tunnel face pressure using both tunneling parameters and geological data as input. The paper proposes a predictive strategy that separates the trend component and fluctuation component from the denoised tunneling data via CCA. Two LSTM-based predictors are presented and combined for the development of a new modeling strategy. The performances of the proposed strategy are illustrated through an application to the Nanning metro. The LSTM model with the proposed strategy gave excellent results in both mudstone and round gravel grounds with an overall R2 value of 0.9974. The paper also presents a comparison of the proposed model with some traditional models as well as a discussion on the importance of input features in different ground conditions.

  1. The effect of block geometry on structural behavior of topological interlocking assemblies

Automation in Construction, Volume 128, August 2021, 103717

Abstract

The principle of Topological Interlocking for masonry construction has gained a growing interest over the last decade due to its special structural properties. This paper presents ongoing research on the correlation between block geometry and structural performance in flat assemblies of convex interlocking blocks. It describes four research stages that analyze different geometries of interlocking blocks through numerical and physical analyses. The results highlight advantageous geometries for simple block types, discuss structural behavior of the blocks under loads, and present novel types of block arrangements that achieve higher load bearing capacity than previously known assembly types while using similar material volume.

  1. Decision support system in management of concrete demolition waste

Automation in Construction, Volume 128, August 2021, 103734

Abstract

Processes of concrete waste management can be carried out using various technological and organizational systems. Such systems must meet the boundary conditions of a given project involving deconstruction of a building and will differ in terms of waste management costs, environmental impact and nuisance to the surrounding community. Selecting the most advantageous solution, taking into account numerous standards such as sustainable development, requires a multiple-criteria analysis of such variants. The system presented in this work supports the decision-making process in terms of choosing a technological and organizational solution in the field of concrete waste management. It is based on a mathematical simulation model, which produces rating indicators for technological-organizational waste management systems. Based on a synthetic rating indicator, the decision maker is provided with a list of ranked variants to choose from. Moreover, the system analyses qualitative parameters, such as the building site area required and waste management time.

  1. Detection of crane track geometric parameters using UAS

Automation in Construction, Volume 128, August 2021, 103751

Abstract

This paper presents the results of experimental and survey work on the application of Unmanned Aircraft System (UAS) photogrammetry to determine the geometric parameters that describe crane ground rails. The goal was to achieve highly accurate measurements (millimeter accuracy) to determine the geometric parameters of elongated engineering objects (of significant dimensions, such as a crane track) up to several hundred meters long and several dozen meters wide. The method of processing images taken with the use of UAS depends on combining images taken at different flying heights and the use of code targets (of appropriately selected sizes), enabling the automatic measurement of controlled points representing the object. The method of fixing the plates with the code target on the crane track is described.

Experimental field work was conducted using a section of crane track of length 35 m whose span was 6.000 m. The proposed method features high accuracy, takes less time and is therefore less expensive than other known methods.

  1. Loose coupling of GIS and BIM data models for automated compliance checking against zoning codes

Automation in Construction, Volume 128, August 2021, 103743

Abstract

Modeling urban data is crucial for supporting automated code checking processes. Ideally, digitally modelled building codes and urban data should be retrieved from municipalities, and the digital building model should be checked automatically based on the collected information. However, BIM tools do not contain and do not allow managing geographical information at a neighborhood scale. Current GIS applications also do not store all of the information required by building codes. Even if they did, interoperability between GIS and BIM environments are problematic.

This paper describes the development of a zoning domain model for automated compliance checking of building projects. The proposed model is illustrated through a proof-of-concept GIS application, where geometric and semantic data are stored, queried and exported as a GML file. Use of this data model for automated code checking is an example for how GIS data can seamlessly complement BIM data making expansion of BIM schemas unnecessary.

  1. A semantic modeling approach for the automated detection and interpretation of structural damage

Automation in Construction, Volume 128, August 2021, 103739

Abstract

During the life-cycle of constructions various influences induce material defects that could affect the behavior of the structural system. Therefore, anomalies that affect heavily stressed constructions, such as bridges, need to be inspected and evaluated regarding their impact on the structural capacity. By using new technologies in the field of damage detection, e.g. laser scanners or unmanned aircraft systems (UAS), this process can be facilitated. However, the classification and assessment of detected anomalies must still be performed in a manual way by human experts due to the lack of machine-processable evaluation methods. In this paper an approach is proposed towards a machine-based damage evaluation, applying semantic web technologies on a new developed method for damage detection on constructions. Thereby, anomalies are detected based on a large amount of high-resolution images from which georeferenced point clouds are calculated by using photogrammetric methods. Using the geometric relations among the image positions and reconstructed points, image features such as anomalies are localized on a 3 dimensional surface. Based on these image features, a web ontology as semantic representation of the recorded damages is generated and linked with an ontology that contains information about the affected construction and its environment. By using predefined rules based on expert knowledge, the detected anomalies are classified and assessed automatically. The inferred information is then used to generate damage representations in a structural analysis model. Furthermore, the geometrical data, which are represented in a model created according to Building Information Modeling (BIM) standards, the semantic data as well as the structural data are linked by utilizing the Multimodel approach.

  1. Reconstructing BIM from 2D structural drawings for existing buildings

Automation in Construction, Volume 128, August 2021, 103750

Abstract

Reconstructing building information models (BIMs) based on 2D drawings is an effective way to realize digital management of existing buildings. However, current image-based methods require much time as well as professional knowledge to manually design and extract features from drawing images. Moreover, the quality of generated BIM cannot be guaranteed when dealing with the drawings drawn under different design standards and drawing conventions. In this study, a novel hybrid method, integrating technologies like image processing, deep learning and optical character recognition (OCR), is proposed to extract the information of objects from the images of structural drawings (i.e. grids, columns and beams), and generate industry foundation classes (IFC) BIM for existing buildings. Experiments are carried out to verify the performance of the proposed method and the results demonstrate the feasibility and reliability of the method. Several accuracy-influencing factors are also analyzed and discussed in this paper.

  1. Nondestructive methods complemented by FEM calculations in diagnostics of cracks in bridge approach pavement

Automation in Construction, Volume 128, August 2021, 103753

Abstract

Nondestructive methods of road pavement diagnostics are an alternative to traditional approach to pavement failure investigation. The article presents a detailed multidisciplinary inspection carried out using ground-penetrating radar (GPR), laser scanning technology and finite element method (FEM) calculations. It was done in order to assess the factors that contributed to occurrence of premature cracks of a bridge approach pavement. Assessments of permittivity values in the GPR method are dependent on two factors: thickness of successive layers and electromagnetic wave reflection in time. Electromagnetic field propagation in the pavement structure was also simulated using two numerical models: the first one reflected the undamaged pavement, while the second one included the defects next to the bridge joint. The comparison of the radargrams for both models enables identification of reflections and anomalies caused by the assumed defects. Nonhomogeneous compaction zones in the bridge approach pavement structure were detected by analysis of layer permittivity and anomalies observed in the in situ GPR maps. The GPR measurements were positively verified afterwards by values of air void content in the pavement layers, determined in standard invasive tests. Laser scanning technology was also used in the distressed area in order to assess its geometric changes. Results are presented in the form of contour plots depicting differences between the measured and the designed surfaces. The three-dimensional finite element (FE) model of the approach pavement was created to determine pavement deformation under moving load and stress state next to the bridge joint. The influence of insufficient support of the top asphalt layers on pavement response was investigated. The analysis of the cracks shows that some errors were made both during the design process and construction of the bridge approach pavement.

  1. Building information Modelling (BIM) application for an existing road infrastructure

Automation in Construction, Volume 128, August 2021, 103752

Abstract

New technologies are changing the sector of infrastructures design and construction. One of the most important is the I-BIM (Infrastructure Building Information Modelling), that is a management information system of digital processes for infrastructures.

In this study the I-BIM approach has been used for the upgrade of a section of the SS 245 road, in the north of Italy, in order to show its benefits applied on existing road infrastructure.

The project involved the design of a new road segment and its connection with the existing road network and with a railway line. These last were respectively solved by a roundabout and by a jacked tunnel under the railroad with wing walls at each exit side of the structure.

The steps carried out in this study were modelling the 3D digital terrain model from point cloud; creating the horizontal alignment, vertical profiles and editing cross-sections; modelling the jacked tunnel; creating the roundabout; generating the 3D parametric model of the complete road and visualizing the infrastructure in the real-world context. The real innovation consists in the creation of a plugin that allows extrapolating directly from the design program to the compute one, all the features need to be calculated.

The BIM tools used were “Autodesk AutoCAD Civil 3D” and “Revit Structure”, used respectively for road geometrical design and for tunnel structural project.

The obtained results have been showed that the I-BIM approach represents not only a powerful tool to optimize and validate the road project according to norms before its construction, but also to see how the infrastructure works with the 3D real environmental context.

  1. Review and analysis of augmented reality (AR) literature for digital fabrication in architecture

Automation in Construction, Volume 128, August 2021, 103762

Abstract

The use of Augmented Reality (AR) technologies has increased recently, due to the equipment update and the mature technology. For architectural design, especially in digital fabrication projects, more designers begin to integrate AR methods to achieve the visualization in the process. To help unskilled labors for holographic on-site previewing and instruction training, experimental and practice-based studies in AR for the architectural digital fabrication have emerged in recent years. Now, it is a great opportunity to discuss the topic of AR in architectural digital fabrication. By presenting a statistical review of AR technology in architecture projects, this literature review aims to review ongoing research and provide pathways for further research in architectural digital fabrication. This review article is based on information found in journal publications and conference papers in the fields of architecture, engineering, robotics, and digital fabrication, published to date (from 2010 to 2020). The review narrows the literature within these papers by filtering 84 articles through the keyword “Augmented Reality”, “Digital Fabrication” and “Assembly”. The selected articles can be categorized based on the most use of AR function in architectural digital fabrication into an order of the following three classifications with the most significant growth in the last years: (A) AR 3D holographic instruction, (B) AR data sharing, (C) AR for Human-Computer interaction. The information collected from these articles within their classifications is meant to give insight into the current state-of-the-art of AR in the architectural digital fabrication area, as well as to summarize how the topic has matured and developed over time in the research and industry literature. This article has not only analyzed the existing literature but also highlighted new emerging fields in AR research and the future trends of AR function in architectural digital fabrication.

VẬT LIỆU XÂY DỰNG

  1. An intelligent humidity regulation material hydrothermally synthesized from ceramic waste

Journal of Building Engineering, Volume 40, August 2021, 102336

Abstract

Huge amounts of ceramic waste are being produced during manufacturing ceramic products in China and even all around the world, which are very difficult to recycle due to its stability by high temperature sintering. With simulating the diagenesis of accumulative rocks underground and cycling their elements of Si, Al and Ca, the ceramic waste has been hydrothermally synthesized into calcium aluminum silicate hydrate (C-A-S-H) gel and further into Al-tobermorite, which are the most important strength-producing constituents of cement/concrete. The formations of C-A-S-H gel and Al-tobermorite are beneficial to both enhance strength and promote porosity of the specimens, favorable to produce a tough porous building material (flexural strength≥20 MPa) for regulating humidity indoors. Introduction of diatomite into ceramic waste samples effectively improved the humidity self-regulating performance (from 50 to 150 g/m2). The increment in moisture self-adsorption/desorption is attributed to the improvement of porosity offered by the both residual diatomite and formed tobermorite in the matrix. Moreover, calcium chloride was also introduced to further promote the humidity regulation performance, and the moisture self-adsorption could increase sixfold (~300 g/m2) than that without calcium chloride addition (~50 g/m2). Different from the diatomite addition, the calcium chloride addition could make more moisture adsorbed by mesopores and provide pores with higher moisture adsorption/desorption ability.

  1. Application of the desirability function for the development of new composite eco-efficiency indicators for concrete

Journal of Building Engineering, Volume 40, August 2021, 102374

Abstract

Studies have been developed to evaluate the construction industry environmental impacts based on eco-efficiency indicators. This work aims to complement impact assessment methods currently used in the literature with the application of the statistical desirability function, and create novel desirability-based indicators to evaluate the environmental and mechanical performance of concrete production. Six new eco-efficiency indicators associated with different impact categories addressed by international, national, and regional agreements in the sustainability area were proposed: Energy Impacts Reduction (EIR); Material Impacts Reduction (MIR); Greenhouse Gases Reduction (GGR); Ecotoxicity Potential Reduction (EPR); Acidification, Eutrophication, and Ozone Abatement (AEO); and Eco-efficiency Potential (EEP). A case study was developed to carry out a life cycle assessment (LCA) of conventional and sustainable concretes, apply the individual desirability methodology and calculate the novel indicators. The application of the desirability function was able to adjust and combine LCA midpoint or endpoint characterization factors and provide very flexible and intuitive desirability-based indicators of concrete eco-efficiency. The desirability-based indicators developed in this work allow assessing the eco-efficiency of cement-based materials in a statistical methodology that offers synthetic results that are easy to understand by the end-user and have great potential for practical application in decision-making processes.

  1. Disposal of wooden wastes used as heavy metal adsorbents as components of building bricks

Journal of Building Engineering, Volume 40, August 2021, 102371

Abstract

The recovery of wastes is the basis of the Circular Economy. In recent years, there is an increased interest in the use of agro-industrial wastes as simple and “low-cost” adsorbents in the removal of heavy metals from wastewaters. However, the fate or reuse of such adsorbents saturated with pollutants has not been discussed deeply. The novelty of this paper is the valorization of pine sawdust waste and pine sawdust char, previously used as adsorbents for Ni(II), Zn(II), Cd(II) and their mixture, in the manufacture of porous fired clay bricks, which are an important kind of bricks due to their low weight and low thermal conductivity. Initially, both residues were evaluated as potential adsorbents for the heavy metals under study. The obtained results were much better for biochar with adsorption efficiencies close to 100%, both in individual and mixed systems, the later closer to real wastewater cases. Finally, 20% by volume of the contaminated biomass waste was incorporated into ceramic matrices, increasing the apparent porosity with respect to a brick of reference. The evaluation of the physical properties and their mechanical characterization, determined a decrease in the quality of these bricks even still within the current regulations for construction purposes. The s-s curves showed differences in the mechanical behavior associated with the type of waste material, being those obtained for bricks with biochar similar to those of the bricks of reference. Heavy metals immobilized in the clay matrix did not introduce significant changes in the physical and mechanical properties checked. Therefore, it is possible to take advantage of wood waste used as heavy metal adsorbents in wastewater treatment, with an option for its proper disposal.

  1. Propose new implement models to determine the compressive, tensile and flexural strengths of recycled coarse aggregate concrete via imperialist competitive algorithm

Journal of Building Engineering, Volume 40, August 2021, 102337

Abstract

This study aims to develop new formulas to predict the tensile, compressive and flexural strengths of recycled coarse aggregates (RCA) concrete. For this purpose, a total of 1348 available experimental results are used. Imperialist Competitive Algorithm (ICA) is employed to find equations based on the content of water, cement, RCA, natural coarse aggregates (NCA) and natural fine aggregates (NFA). In addition, some relationships are developed between flexural, tensile and compressive strengths when different RCA contents are used. To provide the proper equations for estimating the compression, bending and tension capabilities, first the features are considered using the minimum redundancy maximum relevance algorithm that affects the efficiency of the algorithms. Then, the appropriate number of features for estimating each parameter is selected using the Multi-Layer Perceptron (MLP) network. The obtained results showed that the mean absolute error of the proposed formulas in estimating the compressive, flexural and tensile strengths are about 0.54, 0.36 and 0.48, respectively. Additionally, RCA had a substantial influence on the mechanical properties of concrete, and the RCA content should be considered in the formulas utilized to foresee the mechanical characteristics of concrete.

  1. Review of reactive magnesia-based cementitious materials: Current developments and potential applicability

Journal of Building Engineering, Volume 40, August 2021, 102342

Abstract

Previous research on reactive cementitious materials shows that, compared with traditional calcium-based cementitious materials, reactive magnesia-based cementitious materials (an alternative cementitious material) exhibit excellent mechanical properties; different hydration mechanisms, hydration products, and microstructures; and considerably high durability. This paper presents a comprehensive review of the raw materials, hydration products, phase transformation evolution, and crystal structures of reactive magnesia-based cementitious materials. Furthermore, developments in terms of the durability of reactive magnesia-based cementitious materials are summarized and analyzed based on the carbonation performance, water resistance, and brine corrosion resistance. Finally, considering the existing problems and advantages of reactive magnesia-based cementitious materials, potential future research directions are highlighted.

  1. Quantitative determination of processed waste expanded perlite performance as a supplementary cementitious material in low emission blended cement composites

Journal of Building Engineering, Volume 40, August 2021, 102335

Abstract

Ground waste expanded perlite (WEP) is a new pozzolanic supplementary cementitious material of high activity. The use of effective reactive additions allows for a further reduction of the clinker content in the cement while maintaining the strength and durability of the mortars. This is the potential to further reduce the carbon footprint of cement. In the present work, the activity of ground waste expanded perlite was quantified using the k-value concept introduced by the EN-206 European standard for Type II additions. Two methods of k-value determination were used, based on the strength of mortars without and with ground WEP. Mortars made of ordinary Portland cement, as well as blended cements containing up to 80% of granulated blast furnace slag, were investigated in the study. Results showed that a 15% replacement of cement by ground WEP did not cause a decrease in strength. The results obtained showed that k-value equal to 1.0 may be attributed to ground perlite. Carbonation depth measurements revealed that the influence of ground waste expanded perlite on carbonation resistance was similar to the influence of silica fume. In mortars made from cements containing up to 60% of slag, incorporation of ground WEP increased carbonation depth by approximately 1 mm. For cement with 80% slag, the increase in carbonation depth was almost 5 times higher. It was found that the addition of ground waste expanded perlite activates high slag volume cements (CEM III/A and CEM III/B), however, due to increased carbonation, use of ground WEP with cements containing more than 60% of slag should not be appropriate.

  1. Behavior resulting from fire in plasterboard with plastic cable waste aggregates

Journal of Building Engineering, Volume 40, August 2021, 102293

Abstract

This article analyzes the effect of fire on plasterboards with aggregates of plastic cable waste, considering the plaster coating as a strategy to reduce the flammability of the added polymers. A real test was performed, using a direct fire set in a Madrid fire station, and a theoretical estimate of the composition of the gas emissions, focused in CO2 and CO, during a fire in a type room is presented. The results reflect that there is no clear trend between the evolution of temperatures over time and the amount of plastic waste added to the plaster matrix in the different specimens, but a different behavior is obtained depending on the surroundings where they are located. Temperatures of 600 °C are reached between 5 and 10 min after the start of the fire if they are located in a place with heat containment, and they do not reach 400 °C in the same period of time in a place with less heat containment. It was also observed that gypsum can be considered a passive protection of polymers, as it retards the effect of the flame on them. Concerning the gases released, the theoretical calculations, based on the elemental and thermogravimetric analysis of the plastic cable waste, reveal that the amount of carbon dioxide generated in a fire would not pose a risk to people’s health whereas the values obtained for the carbon monoxide exceed the limited considered dangerous to health for a period greater than 15 min. Using plastic cable waste as secondary raw material reduces the number of incinerations to be carried out in landfills with this type of waste, thereby decreasing the potential emission of contaminants into the atmosphere and contributing to the sustainability of our planet.

  1. Effect of carbonation in high chloride-binding capacity mortars subjected to a marine environment at early ages

Journal of Building Engineering, Volume 40, August 2021, 102355

Abstract

This paper presents an experimental research on the effect of carbonation on the chloride penetration in mortars exhibiting a refined porous network and high chloride-binding capacity. The research was focused on the use of metakaolin combined with nanosilica, evaluating the influence of the surface area of the nanoadditions. It was observed that the addition of nanosilica reduces the binding capacity of metakaolin, this reduction was influenced by the type of nanosilica. The analysis of the carbonated samples following carbonation periods of three and six months allowed observing that the free chloride content as well as the bound chloride content are diminished with carbonation. Thence, it can be concluded that the carbonation process hinders the chloride penetration, which can lead to a reduction with time in the chloride concentration of samples.

  1. Seismic assessment of large historic vernacular adobe buildings in the Andean Region of Peru. Learning from Casa Arones in cusco

Journal of Building Engineering, Volume 40, August 2021, 102341

Abstract

The country of Peru has a rich tradition of historic earthen structures from ancient archaeological sites to vernacular and monumental architectures. Nowadays, still a relevant part of the world population lives in earthen houses, which are found to be quite vulnerable to horizontal loading causing considerable loss of life over time. Hence, the importance of studying the seismic performance of these buildings to predict their capacity and failure mechanisms.

After the destruction caused by the 2007 Pisco earthquake, the Getty Conservation Institute initiated a project to better understand the seismic performance of four historic earthen building typologies present in Peru. This paper addresses the seismic assessment of Casa Arones, which is considered as a prototype of the typology of large vernacular houses present in many historical centres of the Andean Region of Peru. Advanced numerical analysis is used to assess the global behaviour of the building, and to identify the damage distribution and failure mechanisms. The challenges faced in the study, related to the complexity of the structure and the insufficient information on its morphology and materials properties, are discussed. Moreover, sensitivity analysis is used to understand the influence of floors and roof on the global behaviour, which is a novel contribution.

  1. Modeling heat and moisture transfer of building facades thermally insulated by the panels with ventilated channels

Journal of Building Engineering, Volume 40, August 2021, 102391

Abstract

This work deals with a numerical study of the thermal and humidity state of a brick wall of a building insulated by panels with ventilated channels in a long-term operation cycle. A new physical and mathematical model has been developed for calculating heat and moisture transfer processes in facades with such panels. The model is based on the joint solution to a system of non-stationary differential equations of heat and moisture transfer in multilayer porous materials, taking into account adsorption processes and phase transitions. In addition, the model includes equations that describe the processes of heat and vapor transfer in ventilated channels. The results of calculations for a sharply continental climate have shown that two characteristic peaks of relative moisture content are observed in the insulating material of the panel. One of them corresponds to late summer – early autumn; the second peak corresponds to winter – early spring. The seasons corresponding to these peaks are the most critical in terms of wetting the mineral wool panel.

  1. Heat transfer mechanism of glazed hollow bead insulation concrete

Journal of Building Engineering, Volume 40, August 2021, 102629

Abstract

In this study, an improved random aggregate adding method was used to develop a microscopic model of glazed hollow bead insulation concrete (GHBIC), and the model’s effectiveness was verified through a test. In addition, the heat transfer performance of GHBIC was also studied using the model. The effect of shape, volume fraction, and gradation of coarse aggregate as well as the volume fraction and gradation of glazed hollow bead on the effective thermal conductivity of this concrete was studied. The results show that the glazed hollow bead effectively blocked the heat flow channel of GHBIC. The smaller the particle size and the higher the volume, the blocking effect is more obvious. Finally, considering the fineness of glazed hollow bead, a mathematical model for the thermal conductivity of GHBIC was established.

  1. Axial compression tests on elliptical high strength steel tubes filled with self-compacting concrete of different mix proportions

Journal of Building Engineering, Volume 40, August 2021, 102678

Abstract

The compaction state and the paste volume of concrete may significantly influence the compressive behaviour of concrete-filled steel tube (CFST) columns, while limited studies have been conducted to understand the compressive behaviour of CFST columns with different mix proportions. This study presents an experimental investigation to the axial compressive behaviour of elliptical CFST (ECFST) column consisting of a high-strength steel (HSS) tube and a self-compacting concrete (SCC) core with different mix proportions. Eighteen ECFST column specimens, fabricated with high-strength elliptical steel tubes in three different cross-sections and three batches of concrete with different mix proportions, were tested under axial compression. The parameters under investigation are the concrete paste volumes (41%, 37% and 32.5%), the cross-sectional aspect ratios (1, 1.5 and 2) and the compaction conditions (with and without mechanical compaction). The standard cylinder tests reveal that SCC without mechanical compaction has a better filling ability and thus a better self-compaction capability when the paste volume is larger than 37%, while SCC with mechanical compaction has the highest strength when the paste volume is the lowest. The axial compression tests show that the peak axial load capacities of ECFST columns are dependent on the paste and aggregate contents in concrete. The compaction state also affects the performance ECFST columns because compaction usually increases concrete strength especially when the aggregate content is high. In addition, it is found that key performance parameters (e.g., strain enhancement ratio, ductility and strength index) all decrease with the increase of cross-sectional aspect ratio due to the non-uniform confinement provided by elliptical steel tubes.

  1. Thermal behavior of beam string structure: Experimental study and numerical analysis

Journal of Building Engineering, Volume 40, August 2021, 102724

Abstract

Due to the dynamic coupling effects of solar radiation, wind, atmospheric temperature and other environmental factors, the temperature field and its effects on a beam string structure under construction or lighting roofs are generally non-uniform and vary significantly. This can affect the structural performance and even lead to potential safety hazards. In order to determine the non-uniform temperature distribution of beam string structure and further analyze the relationship between the temperature field and thermal effects, experiments were designed and conducted on a commonly used one-way beam string to measure the temperature field, cable force and deformation. Based on the test data, the non-uniform features and the time-variation of beam string temperature field was analyzed, and laws for the long-term variations in the cable force and deformation were summarized. The influence of temperature field on thermal effect was also evaluated. Numerical methods for computing the temperature field of beam string structure were proposed considering multiple environmental factors, and the temperature effects were simulated in detail. The experimental study revealed a conspicuously non-uniform temperature distribution and significant thermal effects, and verified the accuracy and effectiveness of the numerical methods. The research methods and conclusions of the present study can provide valuable references for thermal design, monitoring and control of beam string structures.

  1. Seismic behavior of ultra-high performance concrete elements: State-of-the-art review and test database and trends

Journal of Building Engineering, Volume 40, August 2021, 102572

Abstract

The rapidly growing demand for taller buildings and longer span bridges in high seismicity regions obliges structural engineers to develop innovative materials that are stronger and more deformable, and components and structures that are more resilient. Ultra-High Performance Concrete (UHPC) is a promising material to satisfy this demand because of its superior strength, ductility and durability characteristics. This study develops a critical state-of-the-art review of the experimental research work on seismic performance of UHPC structural components. In addition, a comprehensive database for 142 cyclic tests on UHPC components is constructed, presented and analyzed. The seismic behavior of various structural components in literature tests, including columns, beams, beam-column joints, and structural walls, is investigated in detail based on analyzing the observed data trends in the database and past literature test results.

  1. Synthesis and properties of thermally enhanced aerated geopolymer concrete using form-stable phase change composite

Journal of Building Engineering, Volume 40, August 2021, 102756

Abstract

Aerated concrete is composed of a large number of air voids to make it lightweight and to improve the insulation capacity; however, it possesses low thermal energy storage capacity. This paper reports the synthesis and properties of phase change material (PCM) composite integrated aerated/foamed geopolymer concrete (GFC) for enhancing the thermal storage capacity. A paraffin/hydrophobic expanded perlite based form-stable PCM composite was incorporated into the aerated concrete, and the chemical compatibility, mechanical properties, and thermal performance were experimentally evaluated. The FT-IR and TGA tests have indicated that the PCM composite is chemically compatible and thermally stable with GFC. The thermal performance tests on GFC, studied by simulated test rooms, has revealed that the GFC containing PCM composite has very high thermal energy storage capacity. The incorporation of 15% and 30% of PCM composite has reduced the peak indoor temperature of the test room by 1.85 °C, 3.76 °C, respectively while enhancing the thermal storage capacity by 105% and 181%. Despite the reduction in mechanical properties of geopolymer concrete with PCM, the GFC containing PCM has shown enhanced mechanical properties. The air-void distribution had also been improved with the formation of uniform and fine air voids in PCM integrated GFC. The enhancement in mechanical properties and uniform distribution of fine air voids was attributed to PCM composite’s lightweight properties. This has resulted in reduced foam content to meet density requirements, thus increasing the size of gel particulates surrounding the air voids.

  1. Synthesis and properties of thermally enhanced aerated geopolymer concrete using form-stable phase change composite

Journal of Building Engineering, Volume 40, August 2021, 102756

 

Abstract

Aerated concrete is composed of a large number of air voids to make it lightweight and to improve the insulation capacity; however, it possesses low thermal energy storage capacity. This paper reports the synthesis and properties of phase change material (PCM) composite integrated aerated/foamed geopolymer concrete (GFC) for enhancing the thermal storage capacity. A paraffin/hydrophobic expanded perlite based form-stable PCM composite was incorporated into the aerated concrete, and the chemical compatibility, mechanical properties, and thermal performance were experimentally evaluated. The FT-IR and TGA tests have indicated that the PCM composite is chemically compatible and thermally stable with GFC. The thermal performance tests on GFC, studied by simulated test rooms, has revealed that the GFC containing PCM composite has very high thermal energy storage capacity. The incorporation of 15% and 30% of PCM composite has reduced the peak indoor temperature of the test room by 1.85 °C, 3.76 °C, respectively while enhancing the thermal storage capacity by 105% and 181%. Despite the reduction in mechanical properties of geopolymer concrete with PCM, the GFC containing PCM has shown enhanced mechanical properties. The air-void distribution had also been improved with the formation of uniform and fine air voids in PCM integrated GFC. The enhancement in mechanical properties and uniform distribution of fine air voids was attributed to PCM composite’s lightweight properties. This has resulted in reduced foam content to meet density requirements, thus increasing the size of gel particulates surrounding the air voids.

  1. Innovative seismic isolation of masonry infills using cellular material at the interface with the surrounding RC frame

Journal of Building Engineering, Volume 40, August 2021, 102736

Abstract

In this experimental study, a method is presented for the seismic isolation of masonry infill walls from surrounding reinforced concrete frames using polyethylene foam at the interface of infill masonry walls and reinforced concrete frames. The main objective of this research work was to study the change in infill-frame interaction, by using polyethylene sheet for isolation of masonry infill wall from RC frame. For this purpose, two full scaled reinforced concrete frames having infill masonry walls and a window opening, were fabricated. One of the RC infilled frames was having no polyethylene foam at the infill-frame interface (RC Frame 1) while the other frame was having polyethylene foam at the infill-frame interface (RC Frame 2). Data of bare frame was obtained from PhD research work of Engr. Syed Azmat Ali Shah (UET Peshawar, Pakistan). Quasi static cyclic tests were conducted in displacement-controlled manner. Different graphs were plotted from the data obtained during test such as hysteresis curves, energy dissipation curves, envelope or backbone curves, bilinear idealization of backbone curves, stiffness degradation curves and performance levels were also determined for both the RC frames. It is concluded that by using polyethylene foam at the interface of masonry infill wall and RC frame, the infill frame interaction was reduced during early cycles of lateral displacements. At lower values of lateral displacements, response of RC Frame 2 (having PE foam) was similar to bare frame having less stiffness and strength. By further increasing the value of lateral displacement, the polyethylene foam was compressed and therefore infill masonry walls were activated, due to which stiffness and strength of RC Frame 2 were increased and its behavior was similar to infilled frame behavior. It is also concluded that damages produced in infill wall in RC Frame 2 (having PE foam) were less as compared to damages produced in RC Frame 1.

  1. Enhanced surface hardening of hydrated concrete composite by strontium nitrate (Sr(NO3)2) aqueous solution

Journal of Building Engineering, Volume 40, August 2021, 102696

Abstract

This study experimentally investigates the effects of strontium nitrate (Sr(NO3)2) aqueous solution on hardened concrete composite as a surface hardening method. Density, void content, water sorptivity, and surface abrasion resistance of the concrete mixture treated by Sr(NO3)2 solution were measured under diverse curing and treatment scenarios. The results showed that 30% Sr(NO3)2 aqueous solution increases the density by 1.0% and 2.2% and also decreases the void content by 7.4% and 14.4% with the water-cement ratio (w/c) of 0.5 and 0.4, respectively. Water sorptivity of the treated hardened concrete was decreased by 26.4% and 34.0% from the lithium silicate and sodium silicate treatments, respectively. In addition, the Sr(NO3)2 treatment increases the surface abrasion by 45% from the control specimen and about 25–30% from the two silicate-based treatments. X-ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive spectrometer (EDS), and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) were conducted to investigate the micro-morphologies, microstructure, and elemental characteristics. The results illustrate that (1) microstructures of hydrated cement matrix are densified, (2) portlandite (CH) in the matrix decreases as time elapses, (3) multiple types of hydrated aluminosilicate minerals (i.e. zeolites) are formulated, and (4) more subsequent polymerization related to C–S–H/C-A-S-H occurs. Lastly, the densifying and strengthening mechanisms of the hydrated cement by the Sr(NO3)2 treatment process are presented and discussed.

  1. Influence of granite fine powder on the performance of cellular light weight concrete

Journal of Building Engineering, Volume 40, August 2021, 102707

Abstract

As increasing the utilization of granite stone wares, the quantum of granite fine powder substantially increases these days, causing social and ecological issues to the society. This research attempts to use granite fine powder (GFP) as an alternative resource of raw material for making foam based cellular light weight concrete (CLWC). The weight ratios of GFP and binder used in this present study were 0.8:1, 1:1, and 1.2:1. Three different foam-binder ratios, such as 0.025, 0.05 and 0.1 were used in this study. The outcomes obtained from experimental study showed that, comparing with GFP-binder ratio, the foam-binder ratio have a predominant effect on bleeding capacity, flowability, strength, absorption and permeable voids of CLWC. The voids distribution of CLWC during fresh and hardened states is considerably influenced by GFP-binder ratio and foam-binder ratio as inferred from microscopic image analysis. The experimental investigation of this study addresses consensus behavior of GFP based CLWC from materials point of view.

  1. Life cycle cost analysis of lightweight green concrete utilizing recycled plastic aggregates

Journal of Building Engineering, Volume 40, August 2021, 102670

Abstract

The increasing quantities of plastic waste worldwide is an imminent problem with sever environmental impacts. Recent research was able to develop methodologies to recycle plastic waste and use it as a replacement to natural aggregates in concrete. This not only reduces the amount of unprocessed plastic waste, but also minimizes the need for natural aggregates; thus, which in turn reduces the environmental impacts of overexploiting aggregate quarries. The goal of this research is to assess the life cycle cost implications of utilizing green recycled plastic lightweight aggregates (PLA) – specifically those formed of linear low-density polyethylene (LLDPE) – in concrete structures. To this end, the authors considered a concrete structure with multiple variable design parameters, and conducted structural design using conventional concrete and concrete with recycled plastic in an alternating way; with a total of 24 different scenarios. Then lifecycle cost analysis was conducted on these scenarios using construction cost, operation and maintenance, and end of life cost. Finally, a sensitivity analysis was performed to quantify how the structural parameters and cost of key elements impact the cost effectiveness of the LLDPE-based PLA. The findings indicated that using LLDPE-based in concrete structures leads to savings in concrete and steel quantities up to 7.23% and 7.18% respectively depending on the structural configuration of the building. This leads to savings in life cycle costs up to 5.9% depending on the structural configuration and the discount rate. Also, the study revealed that structures with slab spans of around 4 and 5 m benefit the most from the use of LLDPE-based PLA; while those with smaller slab spans of 3 m benefit the least, and sometimes do not benefit at all – financially speaking. The outcomes of this research quantitatively validates the use of green recycled plastic aggregates as a substitute to the conventional aggregates in order to save the limited natural resources. Furthermore, the paper will contribute to the upcoming paradigm shift of utilizing recycled plastic in concrete and using concrete in general as a waste recycling system rather than just a building material; thus, minimizing the environmental impacts of both the concrete and plastic industries as well as helping developers reduce their life cycle costs.