Potential Circular Strategies for Load-Bearing Building Elements at the End-of-Life

Abstract

The growing pressure on planetary boundaries, highlighted by the 2023 Stockholm Resilience Centre report shows that six out of nine boundaries have been exceeded. The construction sector, responsible for 39% of global CO2 emissions, plays a pivotal role in this context. This study examines the potential of circular economy strategies to mitigate the environmental impact of multi-residential buildings, focusing on the end-of-life phase and material recovery during demolition. Circular strategies for structural building elements in multi-residential buildings are investigated through a hotspot analysis of life cycle assessments of Swedish multi-residential buildings and a comprehensive literature review. The analysis identifies that structural elements such as floor slabs and load-bearing walls are the major contributors to the buildings' carbon footprints. The work focuses on the circular economy strategies, element reuse and material reuse by evaluating their applicability to different building elements and by identifying practical approaches to enhance circularity within the construction industry, addressing key technical hurdles and proposing viable solutions for sustainable building practices. Element reuse, although requiring repair and reinforcement due to previous life cycle damage, is deemed highly effective. Material reuse is highlighted as a viable alternative for elements like cross-laminated timber and glulam, especially when element reuse is not feasible. Recycling, while common, often results in downcycling, underscoring the need for prioritizing reuse strategies. The analysis indicated varying strategies are appropriate for different elements. The research identifies significant challenges, including the durability of aged elements, the lack of standardized guidelines, and the complexity of implementing CE strategies for structural elements. Prefabricated elements, such as hollow-core slabs, CLT and Glulam, demonstrate high potential for reuse due to their modular design and ease of recovery. However, in-situ cast elements present greater challenges due to individualized reinforcement layouts and connection areas. The study concludes that a successful transition to a circular economy in the building sector requires collaborative efforts, detailed technical information, and the development of standards to facilitate the reuse and recycling of structural elements.