Cement-stabilization of soil is a common and useful ground improvement method to increase the strength and stiffness of weak soils. The engineering properties of cement-stabilized soil can be affected by the amount of fines in the soil, but there exist controversial views on the effects of fines in the literature, indicating that the underlying mechanism in such cemented soils is not fully understood yet. This paper presents a laboratory study to investigate the effects of fines content on the strength and the wave velocities of cement-stabilized soil using specimens with well-controlled packing densities. The effects of void ratio and cement content are also examined. Experimental results show an interesting finding that the strength and the wave velocities of the cement-stabilized sand first increase and then decrease as the fines content increases from 0 to 15%. The contact and bonding characteristics at the particle level indicate that the strength of the sample is affected by the bonding area and the bonding strength. For a given cement content, the addition of fines increases the bonding area but decreases the bonding strength. Such controversial effects of fines enable to better understand the observed trend of strength variation. A similar mechanism can also be applied to the effects of fines on the wave velocity. Based on the particle-level mechanism, an empirical equation is proposed to characterize the effects of fines. The unconfined compressive strength of the samples can be correlated with the ultra-sonic pulse velocity and shear wave velocity for field monitoring and quality control. The correlations are affected by the fines content.

土壤的水泥稳定化是提高脆弱土壤的强度和刚度的一种常用且有用的地面改良方法。水泥稳定土的工程性质会受到土壤中细粒含量的影响，但是在文献中关于细粒效果的观点存在争议，这表明尚未完全了解此类胶结土壤中的潜在机理。本文提供了一个室内研究，目的是使用具有良好控制的堆积密度的标本，研究细粉含量对水泥稳定土的强度和波速的影响。还检查了空隙率和水泥含量的影响。实验结果表明，有趣的发现是，随着细粉含量从0％增至15％，水泥稳定砂的强度和波速先增大然后减小。颗粒水平的接触和粘结特性表明样品的强度受粘结面积和粘结强度的影响。对于给定的水泥含量，添加细粉会增加粘结面积，但会降低粘结强度。此类有争议的罚款影响使人们能够更好地了解所观察到的强度变化趋势。类似的机制也可以应用于细粉对波速的影响。基于颗粒级机理，提出了一个经验方程式来表征细粉的效果。样品的无限制抗压强度可以与超声波脉冲速度和剪切波速度相关联，以进行现场监测和质量控制。相关性受罚款内容的影响。