The impact of granite powder on the performance and hydration of concrete

Granite manufactured sand typically contains a certain amount of stone powder in engineering applications, and the variation in its content significantly affects the workability, mechanical properties, and cement hydration process of concrete. To systematically reveal the impact of granite stone powder on concrete performance, concrete mixtures were prepared with stone powder contents of 3%, 5%, 7%, 10%, 15%, and 20%. The effects of stone powder content on the workability and mechanical properties of concrete were studied. In addition, cement paste samples with 10% and 20% stone powder content were prepared, and X-ray diffraction (XRD), thermogravimetric analysis (TG-DTG), and scanning electron microscopy (SEM) were used to explore the mechanism of granite stone powder’s influence on cement hydration behavior. The results indicate that granite stone powder content has a significant impact on the workability of concrete: when the stone powder content is too low, the water retention of concrete is insufficient; when the content is too high, the slump is notably reduced. There is an optimal range for granite stone powder content in C30 and C40 manufactured sand concrete, and a moderate amount of stone powder can improve both compressive and flexural tensile strengths. Compared with limestone stone powder, granite stone powder has a larger particle size and an uneven gradation, resulting in a relatively weaker micro-aggregate filling effect and a less pronounced promoting effect on cement hydration. Additionally, granite stone powder reduces the early reaction rate of cement hydration to some extent. The findings provide a theoretical basis for the rational use of granite stone powder in concrete and offer reference value for promoting the application of granite manufactured sand in engineering projects.