Mechanical properties of alkali-activated slag based SIFCON incorporating waste steel fibers and waste glass

This experimental study focuses on sustainable slurry infiltrated fiber concretes (SIFCONs) by utilizing alkali-activated ground granulated blast furnace slag (GGBS) and waste fibers. The waste fibers were high-strength steel fibers recovered from scrap tires. Additionally, waste glass was employed as a substitute for commercial sodium silicate activator, contributing to the reutilization of a waste material. Such an approach stands out for its use of various waste materials to achieve a high-performance concrete primarily composed of recycled materials. Literature survey indicate that there are no studies available on concrete primarily composed of waste or recycled materials. In this study, the molarities of the activators were selected as 8 M and 14 M based on a prior research. Due to the fiber geometry and the associated bulking effect, a maximum waste fiber content of 5 % was adopted, with increments of 1 %. Load–deflection curves of the specimens were obtained in the bending test. Various mechanical properties, including compressive strength, splitting tensile strength, flexural strength, and fracture energy, were determined for the mixtures. The mechanical properties of the alkali-activated mixtures were improved compared to those of the reference concretes. Based on the mixture proportions and materials employed, alkali-activated mixtures in the study achieved compressive strengths exceeding 120 MPa and flexural strengths approaching 30 MPa. Furthermore, significant enhancements in fracture energies were observed. The strengths of the mixtures with waste glass, however, were lower compared to the other mixtures. Nonetheless, in summary, the study shows the promising potential of waste steel fibers and waste glass for the production of alkali-activated slag SIFCON. This approach not only enhances cost-effectiveness, sustainability, and mechanical properties but also reflects a significant step towards achieving a concrete composition that relies solely on waste materials.