Framework for economic assessment of concrete waste management strategies

Optimal site selection for construction and demolition waste disposal using GIS-FAHP: a case study from Kafr El Sheikh City, Egypt

The increasing number of building and demolition projects results in huge amounts of construction and demolition wastes (CDWs) that are illegally dumped. However, these wastes must be disposed of in appropriate legal sites to protect the environment and human health. After reviewing the literature, no prior research examined optimal site selection for dumping or recycling CDW in an Egyptian city. Furthermore, the absence of field surveys did not offer a holistic understanding of the specific criteria used in the model for this region, nor did it permit an assessment of the suitability of existing dumpsites, thereby revealing certain limitations in the final results. In this regard, this research aims to apply a multi-criteria geographic information system (GIS)-based framework to identify an optimal site for CDW disposal in Kafr El Sheikh City. The criteria affecting the site selection are identified and categorized from prior literature, which are further refined using field surveys and focus group to evaluate their applicability in the context of an Egyptian city. After conducting questionnaire surveys, the trapezoidal interval type II fuzzy analytic hierarchy process is applied to compute the weights of the identified criteria from the perspective of each group of experts. The entropy-based aggregation approach is employed to identify the compromise weights taking into account the preferences of different groups. GIS is a powerful tool for geoprocessing and analyzing spatial big data. The result is a scenario map for the optimal site locations with varying suitability scales (i.e., excellent, very good, good, average, poor, and very poor). The proposed methodology provides what-if scenarios based on a selected set of criteria. According to the results of the multi-criteria decision analysis models, the suitability varies based on the weights of the criteria. For the equal-weighted criteria model, the excellent category covers 5.96% of the study area, increasing to 6.48% for the weighted criteria model. These areas primarily lie in the northeast direction. Conversely, the majority of the study area, 41.80% under equal-weighted criteria and 32.39% under weighted criteria, falls within the average and poor suitability categories, respectively. In general, the most suitable areas are located on the outskirts of the city, and the suitability decreases near the central business district. To bridge the gap between research findings and practical applications, a land use analysis employing satellite imagery is conducted to pinpoint suitable locations for CDW disposal. Existing CDW dumpsites predominantly fall within the range of poor to very good for the equal-weighted criteria model, while the weighted criteria model categorizes them into the poor (16.66%) and average (83.33%) categories. The findings demonstrated the applicability of the proposed framework for CDW disposal management and planning.

Construction and Demolition Waste Management Research: A Science Mapping Analysis

Construction and demolition waste treatment has become an increasingly pressing economic, social, and environmental concern across the world. This study employs a science mapping approach to provide a thorough and systematic examination of the literature on waste management research. This study identifies the most significant journals, authors, publications, keywords, and active countries using bibliometric and scientometric analysis. The search retrieved 895 publications from the Scopus database between 2001 and 2021. The findings reveal that the annual number of publications has risen from less than 15 in 2006 to more than 100 in 2020 and 2021. The results declare that the papers originated in 80 countries and were published in 213 journals. Review, urbanization, resource recovery, waste recycling, and environmental assessment are the top five keywords. Estimation and quantification, comprehensive analysis and assessment, environmental impacts, performance and behavior tests, management plan, diversion practices, and emerging technologies are the key emerging research topics. To identify research gaps and propose a framework for future research studies, an in-depth qualitative analysis is performed. This study serves as a multi-disciplinary reference for researchers and practitioners to relate current study areas to future trends by presenting a broad picture of the latest research in this field.

Main Challenges to Concrete Recycling in Practice

While concrete recycling is crucial to protecting the environment, its implementation in practice is low in many countries. This study aims to highlight challenges to concrete recycling. To achieve that aim, the study objectives are (1) to identify the main challenges to concrete recycling in construction projects; (2) to compare the main challenges between small–medium enterprises (SMEs) and large enterprises (LEs); and (3) to determine the underlying groups among the main challenges. Potential challenges were identified through a systematic literature review of journal articles and semi-structured interviews with fifteen industry practitioners. Then, the identified challenges were inserted into a questionnaire survey and distributed to industry practitioners. Eighty-nine valid responses were collected and analyzed using the mean score ranking, normalization, agreement analysis, and factor analysis techniques. The analyses show thirteen main challenges to concrete recycling. The main challenges include increased project duration, lack of national programs, lack of comprehensive rules and regulations, increased project cost, low demand for recycled concrete, low cost-effectiveness of concrete recycling, and increased transportation cost. However, there is no consensus on the criticality between SMEs and LEs. For example, increased project cost is the main challenge for SMEs but is only middlingly ranked for LEs. Finally, the main challenges can be categorized into three interrelated groups: people and technical, legal and environmental, and economic challenges. This study contributes to the literature by analyzing challenges that hinder concrete recycling in practice. The findings allow researchers and practitioners to develop strategies to reduce concrete recycling rejection.

Clean construction and demolition waste material cycles through optimised pre-demolition waste audit documentation: A review on building material assessment tools

Waste from the construction sector poses huge challenges for sustainable waste management. This is not only due to the vast amount of waste produced in construction and demolition activities, but also due to pollutants potentially contained in these products. Subject to these conditions, waste management must ensure recovery of as many resources as possible, while making sure to keep material loops clean. This demanding task requires more knowledge about the existing building stock and an adaptation of current demolition processes. Innovative technologies, such as Building Information Modelling, or modern frameworks, such as Geographic Information Systems, offer a high potential to synoptically provide stock material information for future demolition activities for individual objects to be deconstructed as well as for whole cities as a basis for managing the anthropogenic stock and potential urban mining. Suitable methods of data collection allow for acquiring the desired input for the generation of building stock models enriched with demolition-related information. With the latter, selective deconstruction strategies as well as appropriate waste stream routing agendas can be planned and executed, thereby securing safety at work during the demolition process itself and a waste stream routing according to the waste hierarchy. This review article gives an overview of currently deployed building material assessment tools (data capture and visualisation), both a prerequisite for improved information on materials and geometry (and thereby mass/volume). In addition, this article describes workflows employable for the purpose of urban mining in end-of-life buildings, of which one holistic approach will be described in depth.