Evaluation and prediction on abrasion resistance of hydraulic concrete exposed to calcium leaching

Abstract

This study innovatively establishes quantitative correlations between calcium leaching depth and abrasion characteristics (abrasion depth, volume, and fractal dimension) of hydraulic concrete, investigating the abrasion resistance of hydraulic concrete exposed to calcium leaching. Scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), thermogravimetric analysis (TG), and mercury intrusion porosimetry (MIP) were performed to monitor changes in hydrates and microstructure of cement pastes to dissect underlying mechanisms. A predictive model for the abrasion resistance of concrete under calcium leaching was developed using Gaussian process regression (GPR). The results show that abrasion depth, abrasion volume and fractal dimension of hydraulic concrete are increased with the increase of the degree of calcium leaching. The migration and transformation of calcium ions lead to a reduction in the calcium-to-silicon (Ca-Si) ratio and a morphological change in the C-S-H from fibrous to flaky, resulting in a weakened bonding ability between hydrates. Calcium leaching increases the porosity of concrete, and the abrasion enlarges the proportion of large pores, further intensifying the internal deterioration within the microstructure of concrete. Moreover, the GPR theory is used to establish the prediction model of the morphology index of concrete exposed to calcium leaching, and the predictive model is in general agreement with the experimental data, which has theoretical guiding significance for predicting the durability of hydraulic concrete.