Structural Geopolymer Mortars with Maximum Amounts of Construction and Demolition Wastes

The ecological and health issues of construction and demolition wastes (CDW) accumulation, as well as the depletion of virgin raw materials from the increased use of concrete, is pushing the drive for the reuse of this waste in more construction related applications. The objective of this study is to investigate the production of geopolymer mortars (GM) prepared with maximum amounts of CDW materials such as concrete, red clay bricks, and ceramic tiles, along with smaller contents of supplementary cementitious materials like Fly ash C, ground granulated blast-furnace slag, and metakaolin. The study also examined the effects of concrete waste aggregates (CWA) on the flowability and compressive strengths of GM prepared with CDW-binders and exposed to three exposure conditions of ambient environment, water immersion, and high temperature. An algorithmic mix design method was used to determine the ideal composition ratios of silica oxide to alumina oxide, sodium oxide to silica oxide, and liquid to solid binders. Although, the use of concrete waste aggregates resulted in lower compressive strengths compared to silica sand and natural sand, it was possible to achieve appropriate structural strengths and dimensional stability for high sustainable mortars combining both CDW-binders and CWA-aggregates.