Opportunities and challenges in constructing a demountable precast building using C&D waste-based geopolymer concrete: A case study in Trkiye

As countries worldwide, including Turkiye, grapple with critical challenges in the preservation of natural resources, it is imperative to take urgent and proactive measures that go beyond outdated practices such as using construction and demolition (C&D) waste solely as filler and demolition of the buildings at the end of their service lives. The sustainability of the construction industry is intrinsically linked to the efficiency of C&D waste recycling and the reusability of structural elements after the end of the service life of the buildings. Despite some progress made in recent decades, the production of cement, the extraction of raw materials for concrete, and the generation of construction and demolition waste continue to rise unabated. Recognizing the utmost importance of concrete consumption and waste generation for the world's future, the development of innovative solutions becomes imperative. This study initially introduces the development of a cement alternative called C&D wastebased geopolymer, along with the design of demountable precast structural elements specifically created for deconstruction purposes. To this end, new beam-to-column, column-to-foundation, and slab-to-beam connections are developed and their performances are tested. The tests show that the proposed connections perform ductile bending behavior, and their capacities were sufficient. Most importantly, the C&D waste -based geopolymer shows similar results to its conventional counterpart. Subsequently, the construction of a full-scale, eco-friendly demountable precast building application in Turkiye under real-world conditions is presented, drawing upon the knowledge gained from laboratory experiments. Sustainability analysis of developed geopolymer concrete and demountable precast building is performed. Significant considerations vital to the successful implementation of reusable precast elements are highlighted. Turkiye's current construction and demolition waste handling strategies are discussed, and new strategies are suggested for minimizing waste generation and recycling. The main challenges and opportunities of the prefabrication sector in Turkiye are summarized. Lastly, potential benefits and future direction of the prefabrication are discussed.