Effect of basalt fibers and silica fume on the mechanical properties, stress-strain behavior, and durability of alkali-activated slag-fly ash concrete

Previous investigations have shown that there is limited exploration into the combined mechanism of silica fume and basalt fibers of various lengths on the performance of alkali-activated concrete. Based on this, the primary focus of this study is to elucidate the current knowledge gaps concerning the mechanical properties and durability of basalt fiber-reinforced alkali-activated concrete, with a particular emphasis on its stress-strain behavior. The effects of basalt fiber content (i.e., 0.2%, 0.4%, and 0.6% Vf), basalt fiber length (i.e., 6 and 12 mm), mixing proportions of 6 mm and 12 mm basalt fibers (i.e., 75:25, 50:50, and 25:75) and silica fume content (i.e., 3%, 6%, and 9%) on the workability, mechanical properties, stress-strain behavior, and durability of alkali-activated concrete were investigated. Based on experimental results, predictive models were proposed for the splitting tensile strength, flexural tensile strength, elastic modulus, peak strain, and stress-strain relationship of basalt fiber-reinforced alkali-activated concrete, showing excellent predictive accuracy. Additionally, the durability properties of all samples, including shrinkage, carbonation depth, and chloride ion permeability, were also tested. The results indicate that the combined effect of fibers and silica fume can enhance the mechanical properties and durability of the concrete. Finally, the reinforcement mechanism of the synergistic action of fibers and silica fume is discussed.