Increasing the efficiency of geopolymers based on man-made raw materials

Abstract

Introduction. Geopolymer technology, which involves the synthesis of inorganic polymeric materials based on aluminosilicate raw materials and alkaline activators, is considered the most promising alternative to Portland cement. Aim. Development of a scientifically based technological solution for the production of geopolymer building materials based on hydro-removed ash and slag waste from thermal power plants. Materials and methods. Basalt mineral wool production waste served as the base for the geopolymers. Reinforcement was provided by three types of fiber: steel cord, polypropylene, and basalt wool waste. The developed materials were tested for cone settlement, compressive, flexural, and tensile strength, as well as resistance to chloride penetration. A stress-strain curve was constructed. Results. Despite a significant reduction in workability (due to the fiber), all developed fiber-geopolymer composites maintain a medium workability rating, allowing for efficient formation using vibration compaction methods. An unrein-forced geopolymer sample achieves a strength exceeding that of traditional B30 cement concrete by 28 days. The addition of fiber has little effect on compressive strength. A comparison of the flexural and tensile strengths of 28-day-old samples cured under ambient conditions reveals a similar trend to those of samples tested in compression, demonstrating that polypropylene and metal cord fibers are effective both individually and in combination. Analysis of the stress-strain curves demonstrates that hybridization of fibers of different natures and elastic moduli is the most effective tool for transforming brittle geopolymer rock from man-made raw materials into a highly ductile and energy-absorbing structural material. The diffusion coefficient of chloride ions in the geopolymer. Despite the fact that the diffusion coefficient D Cl – for the developed geopolymer samples in some cases exceeds the coefficient for traditional cement concrete, the obtained values characterize high durability characteristics. Conclusions. Thus, the developed fiber-geopolymer compositions based on man-made raw materials, while maintaining average workability sufficient for effective vibration compaction, surpass traditional B30 class cement concrete in compressive strength at 28 days and demonstrate a significant increase in bending and tensile strength due to both mono-reinforcement and the synergistic effect of hybrid reinforcement with multi-modular fibers. This, combined with the transformation of brittle fracture into ductile fracture and high durability indicators, confirms their potential as a highly effective structural material.