Experimental Study on the Influence of Waste Stone Powder on the Properties of Alkali-Activated Slag/Metakaolin Cementitious Materials

Waste stone powder, as a solid waste resource, is characterized by its large volume, wide distribution, and low utilization rate. Its resource utilization is one of the important approaches to achieving closed-loop recycling development in the stone industry. This study aims to utilize waste stone powder as a mineral admixture in the preparation of alkali-activated cementitious materials, investigating the influence of parameters such as waste stone powder content, water-binder ratio, and Na2O content on the mechanical properties, fluidity, setting time, and shrinkage behavior of the cementitious materials. The results indicate that both waste stone powder and the water-binder ratio can effectively improve the setting time and fluidity of the paste. However, higher waste stone powder content leads to more severe shrinkage, and a calculation model for material shrinkage was established. The optimal mechanical properties for alkali-activated slag samples were achieved with a Na2O content of 8%, waste stone powder content of 16%, and a water-binder ratio of 0.45. For alkali-activated metakaolin samples, a waste stone powder content of 16% resulted in superior mechanical performance. Furthermore, the failure of all material samples was brittle, primarily exhibiting typical splitting failure. Based on damage theory, a calculation model for the load–displacement curve of the material was developed, providing reference and support for further research and application of this material