Sustainable geopolymer composites incorporating waste volcanic tuff and recycled geopolymer concrete powder as base materials

Abstract

The utilization of alternative binders in geopolymer synthesis plays a pivotal role in mitigating environmental impacts, lowering production costs, conserving natural resources, supporting waste management strategies, and enhancing the intrinsic performance of geopolymeric materials. In this study, the influences of concrete geopolymer powder and waste volcanic tuff, used as supplementary binder precursors, on the behavior of geopolymer concrete were systematically investigated under different curing regimes. These waste-derived materials were combined with ground granulated blast furnace slag and polyvinyl alcohol, basalt, and carbon fibers were incorporated into the mixtures to elucidate the role of fiber reinforcement in improving the mechanical performance and structural integrity of the geopolymer matrix. Their influence on the unit weight, porosity, water absorption, strength, microstructural, fire resistance, and abrasion resistance properties of the composites was comprehensively evaluated. Fiber reinforcement enhanced the compressive strength by up to 16 % in recycled geopolymer powder mortars and by up to 23 % in waste volcanic tuff series. The results demonstrate that volcanic tuff and geopolymer concrete waste can be considered as potential sources in geopolymer systems, offering an alternative and sustainable solution for construction applications. Additionally, the carbon emission analysis revealed that the geopolymer mixtures exhibit nearly half the carbon footprint of conventional concrete, further underscoring their environmental advantages.