To determine the performance of metakaolin-based fiber-reinforced geopolymer concrete with recycled aggregates

In the present research, geopolymer concrete for construction applications comprising metakaolin was evaluated by partial addition of recycled coarse aggregates and steel fibers to develop eco-friendly cementitious composites. Mechanical and durability characteristics of geopolymer composites were then assessed such as compression, splitting tensile and flexural strength, water absorption, and drying shrinkage. It was observed that with the inclusion of steel fibers, no significant change in compressive strength occurred. Mixtures were prepared with a binder amount of 440 kg/m(3) in total. The recycled coarse aggregates were substituted with natural coarse aggregates at a rate of 15, 25, and 35% by their weight. The inclusion of steel fibers in the mixes was 1.0, 2.0, and 3.0% of metakaolin content. Because of the addition of steel fibers, the split tensile strength, flexural strength, and drying shrinkage were improved significantly. The load-displacement graph showed that the fracture toughness of geopolymer composites was enhanced due to the inclusion of steel fibers which leads to maximum loads capacity. From the stress-strain curve, it was observed that the geopolymer paste and the steel fibers had a strong bond, which will help in restraining the propagation of cracks. From XRD analysis, it was shown that a mix having 25% recycled coarse aggregates and 3.0% steel fibers in metakaolin-based geopolymer concrete results in environment-friendly composite with suitable strength and durability that will help in bringing sustainability to the construction industry.