Effect of steel fibers and construction demolition waste on fracture behavior of slag-based geopolymer mortar

Abstract

This study investigates the effects of Steel Fibers (SF) and Recycled fine Aggregate (RA) from Construction and Demolition waste (CDW) on the mechanical and fracture properties of Steel Fiber-Reinforced Geopolymer Mortar (SFRGM). SF was incorporated at varying volume fractions (0%-1.25%), while natural sand was replaced with RA at levels of 0%, 10%, 20%, and 30%. The study examines compressive strength, splitting tensile strength, and flexural strength, as well as fracture characteristics such as load-deflection behavior, peak load, and fracture energy using three-point bending tests on notched beams. Results show that up to 20% RA replacement caused moderate reductions in compressive, tensile, and flexural strengths, with more pronounced decreases at 30% RA. The inclusion of SF notably improved strength parameters by 20%, 45%, and 80%, respectively, while enhancing ductility and energy absorption. Although RA slightly lowered fracture energy, SF significantly increased it, with a 1% SF content yielding approximately 59 times the fracture energy of the control sample across all mixes. These findings suggest that integrating RA and SF in SFRGM offers a potential alternative to conventional cement-based materials.