在机制砂制备过程中，大量石粉被筛分掩埋，导致资源浪费和环境污染。为提高机制砂石粉利用率，将废弃石粉高值化应用在混凝土中，并将机制砂中的石粉视作胶凝组分替代水泥，使用XRD、TG、SEM等测试手段研究花岗岩石粉对硬化水泥浆体微结构演变的影响，确定了石粉替代水泥最佳范围。通过调控机制砂石粉含量、粗骨料级配、砂率与水胶比等，优化混凝土工作性能和力学性能，揭示浆体体积分数对混凝土工作性能和力学性能的影响机制，利用高石粉含量机制砂制备了低成本、工作性能与力学性能满足要求的混凝土。结果表明：石粉替代10%（质量分数）的P.II 52.5硅酸盐水泥时，7 d和28 d浆体水化产物数量没有明显减少，微结构仍然较为致密；当石粉替代水泥比例超过20%（质量分数）时，浆体中水化产物数量减少超过20%（质量分数）、孔隙增多，导致强度大幅度降低；随机制砂石粉含量的增加，相同坍落度下混凝土减水剂掺量有所增加，浆体体积分数在31%~32%时，混凝土可获得良好工作性能和力学性能。在此基础上，采用石粉含量（质量分数）为15.1%、16.5%和18.7%的机制砂分别制备了满足工程性能要求的C30、C40和C50混凝土，水泥用量分别减少54、63和92 kg/m³，显著降低了混凝土成本和碳排放。

During the production of manufactured sand, a large amount of stone powder was sieved and buried, leading to resource waste and environmental pollution. To improve the utilization rate of manufactured sand stone powder, this study explores the high-value application of waste stone powder in concrete. By treating the stone powder in manufactured sand as a cementitious component to partially replace cement, the effects of granite stone powder on the microstructural evolution of hardened cement paste were investigated using XRD, TG, SEM, and other characterization methods, leading to the identification of the optimal cement replacement range. Furthermore, by adjusting the stone powder content in manufactured sand, coarse aggregate gradation, sand ratio, and water-to-binder ratio, the workability and mechanical properties of concrete were optimized. The study reveals the mechanism by which paste volume fraction influences concrete’s workability and mechanical performance, and successfully produced low-cost concrete with acceptable workability and mechanical strength using manufactured sand with a high stone powder content. The results show that cement paste with 10% stone powder retained a denser microstructure, as the amount of hydration products showed negligible reduction compared to that of pure cement paste after 7-day and 28-day curing. However, when the substitution of cement with stone powder exceeded 20%, the amount of hydration products decreased significantly by more than 20%, leading to a porous microstructure and lower compressive strength compared to that of pure cement paste. When manufactured sand (MS) with high stone powder content is used in concrete production, the dosage of superplasticizer needs to be increased slightly under the same slump requirement. Additionally, the optimal workability and mechanical properties of MS concrete were achieved when the volume fraction of paste lay in the range of 31~32%. Consequently, C30, C40, and C50 concretes meeting target property requirements were prepared using MS with 15.1%, 16.5%, and 18.7% stone powder content, respectively, resulting in cement consumption reductions of 54, 63, and 92 kg/m³, and thereby significant reductions in cost and carbon emissions.