Microstructure-based Investigation of the Mechanical and Gas Permeability Properties of Stone Powder-doped Mortar

Abstract

In view of the increased focus on “green” and sustainable development and compliance with the national strategy for “carbon peak and carbon neutrality,” this study investigated the effect of replacing cement (0–20%) with limestone powder (stone powder) as a mineral admixture on the micro, meso, and macro properties of mortar. First, the applicability of stone powder was examined based on the physical filling and heat of hydration of stone powder-cement. Second, micro-meso testing methods, such as X-ray diffraction, scanning electron microscopy, thermogravimetry-differential scanning calorimetry, and nuclear magnetic resonance, were utilized to reveal the influencing mechanisms of stone powder on the microstructure of the mortar. Furthermore, the effect of stone powder on the compressive strength and gas permeability of the mortar was analyzed. Additionally, the time-dependent variations in the gas permeability and its functional relationship with the mechanical properties were determined. Finally, the correlation between the compressive strength and gas permeability with respect to the pore size of stone powder-doped mortar was established via gray-correlation analysis. The results show that an appropriate amount of stone powder (5%) can effectively improve the particle gradation, decelerate the release of the heat of hydration, increase the amount of hydration products, and improve the pore structure, thereby increasing the compressive strength and reducing the gas permeability coefficient. The gas permeability of stone powder-doped mortar was found to exhibit good time-dependent characteristics as well as a quadratic linear correlation with the compressive strength. The gray-correlation analysis results indicate that air pores exhibit the highest influence on the compressive strength and that the gas permeability coefficient is most significantly affected by large pores.

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Wuhan University of Technology and Springer-Verlag GmbH Germany, Part of Springer Nature