Abstract

Soil solidification with cement is widely adopted to improve soil strength and stiffness. However, a large amount of cement may be consumed for ideal soil solidification. Therefore, a method was proposed using waste powders crushed from discarded brick and concrete as alternative materials to partially or fully replace the cement in soil solidification. The influence of the substitution rate and particle size of waste powders on the efficiency of solidification was studied. Scanning electron microscopy (SEM), water content analysis, direct shear tests, and unconfined compression tests were conducted at varying curing days. The results revealed that a lower substitution rate or smaller particle size generally led to denser soil structures and lower water content of the sludge. The unconfined compressive strength, cohesion, and internal friction angle of solidified sludge decreased slightly within around 6% when the substitution rates gradually grew to 40% and reduced by 19% approximately with the particle size rising from 0.045 mm to 1 mm. Besides, compared with brick powder, the concrete powder had a more positive impact on solidification. Consequently, the concrete powder with the smallest particle size of 0.045 mm and substitution rate less than 40% is recommended for replacing cement in solidification.

摘要

用水泥固化土壤被广泛用于提高土壤强度和刚度。然而，理想的土壤固化可能会消耗大量的水泥。因此，提出了一种利用废弃砖块和混凝土破碎的废粉作为替代材料，部分或全部替代土壤固化中的水泥的方法。研究了废粉的替代率和粒径对固化效率的影响。在不同的固化天数进行扫描电子显微镜 (SEM)、含水量分析、直接剪切测试和无侧限压缩测试。结果表明，较低的替代率或较小的粒径通常会导致土壤结构更密集，污泥的含水量更低。无侧限抗压强度、凝聚力、当置换率逐渐增加到40%时，固化污泥的内摩擦角在6%左右略有下降，随着粒径从0.045 mm增加到1 mm，内摩擦角下降约19%。此外，与砖粉相比，混凝土粉对凝固的影响更大。因此，推荐使用粒径最小为 0.045 mm、替代率小于 40% 的混凝土粉末替代凝固中的水泥。