Material Expert Interviews - Construction Waste and Materials
Amal Bakchan and Beatriz Guerra
Materials Lab: Please tell us your title, and relationship to materials
Amal Bakchan: Title: PhD Candidate | Graduate Research Assistant; in Sustainable Systems program, at the Department of Civil, Architectural, and Environmental Engineering
Relationship: One of my research areas focuses on construction waste (CW) generation and management/handling practices.
Beatriz Guerra: I’m a Ph.D. student of the CAEE (Civil, Architectural, and Environmental Engineering) department in the Sustainable Systems program. My research is on construction waste management and Building Information Modeling (BIM). Therefore, due to my research topic, I have a very close relationship with materials, especially the ones that are mainly wasted on job sites - for instance, concrete, wood, drywall, masonry, steel, tiles.
ML: How has your relationship to materials changed over time?
AB: My journey with materials, specifically construction materials, started in 2013, where I was interested to understand the sources of waste generation in the construction sites, as well as the quantities generated from construction activities (e.g. concrete casting, masonry work). I started with frequent field visits to closely monitor the ongoing construction activities, learn from construction workers’ previous experiences with materials, and acquire improved understanding of processes that contribute to CW generation. I then worked on multiple research studies that propose methods to estimate CW generation, ranging from field data, to data reported in waste hauling tickets, and automated bill of quantities.
My expertise in CW quantification has then enabled me to explore various CW management practices, from reduction, to reuse, and recycling. In this respect, I focused on understanding the behavioral determinants of CW management at the site level, and how technology, such as Building Information Modeling, can be used to improve the onsite adoption of these practices.
BG: While I was a civil engineering undergraduate student back in Brazil, I thought of materials as resources that would enable me to have my projects’ ideas actually built in the environment. At that time I was mainly focusing on the use of materials during design. I was not very aware of the material waste generated during construction activities, and in my mind construction waste was not a big issue – or at least it was an inevitable issue.
However, as I became a graduate student at UT, I was involved in a sustainability research project that was related to automating construction waste estimation. When I started researching about the construction waste issue I was shocked by the numbers! For example, according to the Environmental Protection Agency (EPA), in 2015, 548 million tons of construction and demolition waste was generated in the U.S. – to put this number in perspective, this is equivalent to 1500 Empire State buildings in one year!
Right now my mindset is more focused on how we should be more efficient in terms of materials usage and waste management in construction job sites.
ML: How is construction waste related to material design and reuse?
BG: Construction waste is intimately related to design and materials reuse. The way we design our products – in my context, buildings – really affects the amounts of waste generated at the product’s end-of-life phase. Decisions made early in design also influence the likelihood of reusing those materials in different projects – some types of decisions that influence reuse are the use of finishes or not, use of toxic materials, and how the materials are assembled together (e.g. glued, or bolted). Construction waste reuse is also largely affected by external factors such as policies incentivizing it, the easiness of certifying these materials and incorporating them back into the construction supply chain, the supply and price of virgin materials, etc.
ML: What are some of your research findings that you think are the most interesting?
AB: Some of my interesting research findings revealed a greater sensitivity of construction workers’ behavior towards CWM to personal factors (e.g. attitude, awareness) than to corporate factors (e.g. supervision). This finding emphasizes that promoting best practices is a behavioral and social process, and thus raises considerable attention to the role of human factors in minimizing and managing CW.
Additional interesting findings relate to the contribution of effective CW management—leveraging Building Information Modeling—for improving the sustainability, schedule, and cost performance of the construction projects. This finding contradicts the false conception that CW management interferes with normal site activities and is not cost-effective.
ML: What innovations are being done to reduce construction waste?
BG: I think that there are several innovations related to construction waste management, especially in recent years. Construction waste is an issue largely discussed by both academics and industry practitioners nowadays; if we look back 5 to 10 years ago, several digital applications to streamline construction waste management did not exist – including the use of BIM for this purpose. But aside from applications and software systems, in my opinion, one of the most important “innovation” (although I don’t think innovation is the best word) to reduce construction waste is the concept of circular economy.
Circular economy is an alternative to our current linear economic model - which the construction sector is still rooted in (i.e. the “take-make-waste” mindset). In this new context, buildings are made to last longer, to be reused or refurbished to its maximum extent, and then once the end of life is actually reached, the building’s components are not viewed as waste, but more like resources for different projects. One practical example of circular economy implementation is the “BAMB” pilot project in Europe – the ultimate idea of this project is to implement strategies along the building lifecycle in order to make buildings function as “materials bank” for other construction projects (therefore minimizing construction waste). Of course, several changes are needed in the construction industry in order to completely change to a circular economy, however, some geographic regions like Europe are already moving towards this direction in terms of policies. I think the circular economy concept applied to the built environment will have a positive and soothing effect on the construction waste issue!
ML: What do most people misunderstand about materials (either in general, or those you work with specifically)?
AB: There is a false preconception that CW management (e.g. reduction, reuse, recycling) contributes highly to project expenses, or the perception of CW management as an activity with a low priority compared to other objectives for meeting project deadline and maximizing profit. On the contrary, my research findings revealed that the integration of CW management applications—e.g. disposal scheduling, disposal cost estimation, and reuse planning—with project scheduling and budget estimation fields may improve the efficiency of these fields as well as promote better implementation of CW management.
--Many thanks to both Amal and Beatriz for participating as Material Experts!