Waste Produced by Construction Industry

Beyond Demolition: Glass Reborn in Concrete

1. Precedent Projects

The construction industry generates vast amounts of waste, posing a significant challenge to environmental sustainability. Glass, a popular facade element, is often discarded in landfills at the end or during a building’s life. The research explores the potential to “rebirth” this demolition glass within new concrete facades. By transforming this waste stream into a valuable design element, this research aims to redefine our approach to heritage facades while promoting transformative practices in concrete application. This approach aligns with growing efforts in the construction industry to embrace circular economies, while Liu and Poon (2019) note that efforts are already underway to “turn waste glass into a valuable resource in cement-based products” (Liu and Poon 2019). Exploring the feasibility of reusing demolition glass within concrete facades addresses the issue of waste while offering potential aesthetic, economic, and environmental benefits. The research investigates the technical considerations, design possibilities, and the broader potential for reintegrating glass into the built environment, paving the way for more sustainable and innovative facade design.

 1.1. Classification of glass façade waste

Its composition must be precisely characterized to find the best choices for recycling and reusing glass facade trash. Most façade panels comprise one of three primary kinds of glass: float glass, laminated glass, or insulated glass units (IGUs). Most buildings utilize float glass, as the material—used for windows—is thin and affordable. Laminated glass is rarer to find, but it keeps the fragments together when undergoing fracture. Often toughened, two or more sheets of glass are fused to form laminated glass. These sheets are laminated or bonded together using a plastic laminate, and this type of glass is available in different thicknesses and varieties. Usually, construction companies make panels out of this (North 2022). IGUs are composed of two panes with an air gap between them for insulation. They are sometimes used in photovoltaic applications (Zhang et al., 2017). Distinct types of glass need distinct recycling processes because they include varied combinations of raw ingredients such as sand, soda ash, and lime. Because leftover coatings or paint might impede future use, the amount of contamination is equally critical. Advanced cleaning is necessary for heavily polluted glasses to eliminate impurities that might damage the durability, mechanical qualities, or aesthetics of the concrete if deposited throughout the material. In order to develop effective recycling strategies, conducting a thorough analysis of glass properties is crucial.

 1.2. Environmental impact of glass façade waste

Glass façade waste from construction has a considerably negative environmental impact. Adekomaya and Majozi (2021) suggest that it is “one of the major challenges crippling sustainable waste management and mitigation” (Adekomaya and Majozi 2021, 10488). Even with advanced technical methods, recovering recyclable elements from broken glass is time-consuming and laborious. Problems arise when the quantity of waste glass rises, and landfill space is reduced, as is the case with worldwide containment efforts. Glass remanufacturing is complex and costly, requiring "huge commitments” (Adekomaya and Majozi 2021, 10488). Studies have shown that most glass waste comes from beverage bottles and construction. For example, over 80% of disposed glass in some areas is from drink containers. Similarly, less than 10% of glass waste in Hong Kong is recycled, while over 90% is in landfills. The enormous volume of glass being landfilled presents a huge environmental burden, as landfilling depletes limited space and results in glass permanently occupying space in landfills. Further, the growing global demand for materials increases the amount of glass waste generated each year, exacerbating the environmental impacts of glass disposal if not managed sustainably (Adekomaya and Majozi 2021). Also, this comes from the glass used in material products, like drink containers, while it does not account for the massive amounts of waste generated from construction sites of structures like buildings and homes.

Furthermore, natural resources become depleted, making it more difficult to manufacture an increasing amount of glass in demand. Adekomaya and Majozi (2021) note that there has been a dramatic growth in the quantity and variety of glass items used in recent years, together with the number of people producing waste glass. Global glass output was anticipated to be close to 130 Mt in 2005, with other supporting fibers seeing similarly strong demand. Additional research showed that of all the glass fibers generated, around 25% went into making container glass, while 33% went into making flat glass. Due to these demands, massive amounts of glass fiber have been produced, with little or no infrastructure to deal with the resulting trash (Adekomaya and Majozi 2021). In other words, glass production is outpacing recyclability at the current rate. 

 1.3. Current practices of glass facade waste

There are issues with current practice that require solutions. Vast amounts of glass from deconstructed buildings regularly end up in already overflowing landfills each year. Disposing of this recyclable material in this manner wastes valuable resources, as glass could otherwise be recovered and used again in new applications. Some recycling initiatives have emerged to address this problem, but there are also limitations to recycling all glass waste streams. According to Imteaz et al. (2012), a cullet is a glass-related product often stored outside, while contaminants can gather on its surface. Logistics in collecting, transporting, and incorporating the used glass hamper the more widespread implementation of recycling construction waste glass. Design specifications and aesthetic considerations of buildings also impact the feasibility of reusing glass modules. Specific requests for unfulfillable glass could be made via a recycling process. For instance, glass used for certain types of skyscrapers may need to withstand high wind loads or meet stringent safety standards. Some of the potential solutions to these issues include developing standardized processes for sorting, cleaning, and processing recycled glass to remove contaminants and prepare the material for reuse and conducting research on techniques like glass refinement that could upgrade recycled glass to meet various engineering/aesthetic requirements. More efficient recycling facilities could help handle waste volumes. Additionally, researchers should conduct studies on glass refinement so that it can meet engineering and aesthetic requirements.

 1.4. Current implementation of glass facade waste into concrete

• Glass Fiber Reinforced Concrete (GFRC): Existing technology using fine glass fibers to create lightweight, precast concrete panels, but often limited in structural capacity and applications.
• Terrazzo and Exposed Aggregate Concrete: Decorative applications utilizing larger glass pieces embedded in concrete for aesthetic purposes but raise concerns about structural integrity and limited control over recycled glass characteristics.
• Case studies of projects incorporating recycled glass in concrete facades
• Challenges and Limitations of Existing Applications: Existing applications often face limitations in structural capacity, aesthetic control, or widespread adoption due to technical or economic barriers.

Bibliography

Adekomaya, Oludaisi, and Thokozani Majozi. 2021. “Mitigating Environmental Impact of Waste Glass Materials: Review of the Existing Reclamation Options and Future Outlook.” Environmental Science and Pollution Research 28 (9): 10488–502.

Glass Doctor. 2022. “What Is an Insulated Glass Unit or IGU?” Glass Doctor. 2022.

Imteaz, Monzur Alam, MM Younus Ali, and Arul Arulrajah. 2012. “Possible Environmental Impacts of Recycled Glass Used as a Pavement Base Material.” Waste Management & Research 30 (9): 917–21.

Lu, Jian-Xin, and Chi Sun Poon. 2019. “6 – Recycling of Waste Glass in Construction Materials.” Edited by Jorge de Brito and Francisco Agrela. ScienceDirect. Woodhead Publishing. January 1, 2019.

North. 2022. “Differences between Float Glass, Tempered Glass and Laminated Glass.” Beijing Northglass Technologies Co., Ltd. 2022.

Zhang, Weilong, Lin Lu, and Xi Chen. 2017. “Performance Evaluation of Vacuum Photovoltaic Insulated Glass Unit.” Energy Procedia 105 (May): 322–26. https://doi.org/10.1016/j.egypro.2017.03.321.