Mechanical properties of basalt and polypropylene fibre-reinforced alkali-activated slag concrete

Alkali-activated materials have received considerable attention in regarding their use as environmentally sustainable alternatives to Portland cement. However, the brittleness and shrinkage cracking of these materials have hindered their wider application. An effective solution to these problems is adding fibre to the concrete. This study investigated the mechanical properties of basalt and PP fibre-reinforced alkali-activated slag (AAS) concrete. A total of 11 mixture groups with different fibre dosages and lengths were created, and 132 samples were subjected to cube compressive, prism compressive, splitting tensile, and flexural strength tests. The influence of the fibre dosage and length on the mechanical properties was determined. Owing to the different strength calculation formulas and large shrinkage of the AAS material, significant differences are observed when the tensile strength of AAS concrete is characterized analysed through splitting tensile and flexural strength tests. For the same fibre length and dosage, PP fibre did not improve the strength of AAS concrete as effectively as basalt fibre did. According to the experimental results, a mathematical method was proposed to determine an optimal solution to the bivariate problem.