Effects of ultrafine glass powder on the reliability analysis and life prediction of cement mortar under multi-concentration sulfate attack

Abstract

In this paper, the influence mechanism of ultrafine glass powder (UGP) on the sulfate resistance of cement mortar is studied by replacing cement with different of equal quality amounts. The reliability analysis of UGP-modified cement mortar in sulfate environment is systematically discussed by mass change analysis, scanning electron microscope (SEM), X-ray diffraction (XRD) and nanoindentation, etc. The results show that the proper amount of UGP can significantly improve the sulfate resistance of cement mortar, and the effect is the best when the content of UGP is 10%. Compared with the undoped UGP group, the flexural strength and compressive strength increased by 11.34%, 8.62% and 6.63%, 6.85% respectively after 120 days of erosion in 5% and 10% sodium sulfate solutions, and the mass loss was the smallest. A two-parameter Weibull distribution model via relative dynamic elastic modulus is developed to predict the reliability life of UGP-modified cement mortar. The results show that 10% UGP content can significantly prolong the service life of cement mortar in sulfate environment. UGP effectively consumes Ca(OH)₂ through pozzolanic reaction, which promotes the formation of C-S-H gel and reduces the formation of expansion products such as gypsum (CaSO₄·2 H₂O) and ettringite (AFt), as well as optimizes pore structure and enhances material compactness and microscopic mechanical properties.