Durability Performance of Recycled Aggregate Geopolymer Concrete Incorporating Fly Ash and Ground Granulated Blast Furnace Slag

Abstract

The construction industry must adopt a sustainable and environmentally friendly approach because it heavily relies on natural resources. To tackle this issue, the utilization of industrial by-products such as fly ash (FA), ground granulated blast furnace slag (GGBS), and recycled aggregates (RAs) from building demolition waste has emerged as a significant sustainable element in the production of recycled aggregate geopolymer concretes (RAGPCs). This study evaluated the durability performance and life-cycle assessment (LCA) of FA-GGBS–based RAGPC adhering to German specifications to optimize aggregate particle packing. Six different mixes of RAGPC were developed with various alkaline-activator content (AAC)/binder (B) ratios, ranging from 0.3 to 0.8. The concrete was cast and then ambient cured until testing. Various tests were carried out to evaluate the performance of RAGPC. The tests included compressive strength, durability, water absorption, and volume of permeable pores. The durability was measured using water sorptivity and water permeability tests. In addition, microstructure characteristics, embodied energy, and global warming potential as part of LCA also were evaluated. It was found that ambient-cured geopolymer concretes demonstrated good strength gain, normal pore structure characteristics, and good durability. Strengths ranging from 30 to 64 MPa can be developed with RA and geopolymer binders. The durability of the RAGPC gel and its capillary porosity resulted in water absorption of less than 10%. The water permeability results indicated reduced penetration. In terms of LCA, the RAGPC had an embodied energy of 4.48% and a global warming potential of 0.083, both of which are significantly lower than those of conventional concrete.