Influencing factors analysis and optimized prediction model for rheology and flowability of nano-SiO2 and PVA fiber reinforced alkali-activated composites

Alkali-activated composites (AAC) has real potential as a repair material of defective concrete structures by virtue of fast setting, high strength, and recyclability . Understanding the workability of AAC is the key to realize this environmental technology as a new repair material. In this work, the effects of water-reducing admixture, nano-SiO 2 (NS), and polyvinyl alcohol (PVA) fiber contents on the rheology and the flowability of AAC were investigated through the impeller-rheometer and L-box tests respectively. Based on the results of rheology and flowability, the least squares support vector regression (LS-SVR) method was used for the multi-output prediction of the rheological parameters of AAC. The test results indicate that the fresh mixtures can be regarded as a Bingham fluid, and the proper NS and water-reducing admixture contents can promote the rheology and the flowability of the mixtures, while excessive PVA fiber and NS have negative influence on the workability. The predicted results exhibit that the predicted rheological parameters of mixtures are concordant with the experimental values (the correlation coefficients of static yield stress, dynamic yield stress and plastic viscosity are 0.990, 0.963 and 0.976, respectively). Consequently, the LS-SVR method can be applied for the inverse analysis of the rheological parameters of AAC.