Ye Yuchen, Gu Zhenyuan, Wang Yi, Sun Ying, Zhu Chenhui, Yang Jie
School of Transportation and Civil Engineering, Nantong University, Nantong 226019, China.
Materials (Basel). 2025 Jun 13;18(12):2797. doi: 10.3390/ma18122797.
Sand content plays a critical role in regulating the structural compactness and strength development of alkali-activated slag cementitious materials. In this study, three types of specimens-pure slag paste, standard sand mortar, and fine sand mortar-were prepared to investigate the effects of sand incorporation on pore structure and fractal characteristics. Mechanical properties, pore structure, and micro-morphology were systematically evaluated at different curing ages. Mercury intrusion porosimetry (MIP) was employed to measure porosity, pore size distribution, and the threshold pore diameter, while fractal dimensions were calculated to quantify pore complexity and compactness. The results showed that the pure slag paste achieved the highest compressive strength at all ages but posed environmental concerns due to high resource consumption. In contrast, sand-incorporated mortars exhibited stable strength development and continuous pore structure refinement. Notably, the use of fine sand in Group C reduced slag content by approximately 5.6% compared to Group A, contributing to lower CO emissions and enhanced sustainability. Fractal analysis revealed a strong correlation between fractal dimension, pore compactness, and compressive strength. A higher fractal dimension indicated a more complex and interconnected pore network, promoting matrix densification. At 90 days, Group C achieved the highest fractal dimension and lowest porosity, attributed to the micro-filling effect of fine sand, which facilitated the formation of a denser and more continuous gel network. These findings provide a theoretical foundation for the multiscale characterization of alkali-activated cementitious systems and support the design of more sustainable mix formulations.
砂含量在调控碱激发矿渣胶凝材料的结构致密性和强度发展方面起着关键作用。在本研究中，制备了三种类型的试件——纯矿渣浆体、标准砂砂浆和细砂砂浆——以研究掺入砂对孔隙结构和分形特征的影响。在不同养护龄期对力学性能、孔隙结构和微观形貌进行了系统评估。采用压汞法（MIP）测量孔隙率、孔径分布和阈值孔径，同时计算分形维数以量化孔隙复杂性和致密性。结果表明，纯矿渣浆体在所有龄期均获得了最高的抗压强度，但由于资源消耗高而存在环境问题。相比之下，掺入砂的砂浆表现出稳定的强度发展和持续的孔隙结构细化。值得注意的是，与A组相比，C组使用细砂使矿渣含量降低了约5.6%，有助于减少二氧化碳排放并提高可持续性。分形分析表明分形维数、孔隙致密性和抗压强度之间存在很强的相关性。较高的分形维数表明孔隙网络更复杂且相互连通，促进了基体致密化。在90天时，C组获得了最高的分形维数和最低的孔隙率，这归因于细砂的微填充效应，其促进了更致密和连续的凝胶网络的形成。这些发现为碱激发胶凝体系的多尺度表征提供了理论基础，并支持了更可持续的配合比设计。
