武汉地区粉煤灰和膨润土双掺合剂水泥土性能改良试验研究

Experiment on performance improvement of cement-soil with the dual admixture of fly ash and bentonite in Wuhan area

摘要:

近年来，水泥土被广泛应用于土体加固工程，其强度与加固效果密切相关。为研究膨润土和粉煤灰掺量对水泥土性能的影响，对25组不同膨润土和粉煤灰掺量的水泥土进行基本力学性能试验。通过抗压强度试验，发现当粉煤灰和膨润土掺量分别为40%和11%时，28 d的水泥土抗压强度最大，为7.30 MPa；当粉煤灰和膨润土掺量分别为20%和7%时，90 d的水泥土抗压强度最大，为7.19 MPa。通过室内直接剪切试验，发现当粉煤灰和膨润土掺量分别为20%和11%时，28 d的水泥土抗剪强度参数粘聚力c最大，为1144.8 kPa；当粉煤灰和膨润土掺量分别为30%和5%时，90 d的水泥土抗剪强度参数粘聚力c最大，为1753.71 kPa。研究成果可以为武汉地区的粉煤灰和膨润土双掺合剂改良水泥土的现场施工提供参考依据。

关键词:水泥土性能;膨润土;粉煤灰;掺量;抗压强度;抗剪强度;土体加固;武汉地区

Abstract:

In recent years, cement-soil has been widely used in soil reinforcement projects, and its strength is closely related to the reinforcement effect. In order to study the effect of the adding amount of bentonite and fly ash on the performance of cement-soil, the basic mechanical properties of 25 groups of cement-soil with different adding amount of bentonite and fly ash were tested. Through the compressive strength test, it was found that when the blending amount of fly ash and bentonite was 40% and 11% respectively, the 28d compressive strength of cement soil was the largest at 7.30MPa; when the blending amount of fly ash and bentonite was 20% and 7%, the 90d compressive strength of cement-soil was the highest at 7.19MPa. Through the indoor direct shear test, it was found that when the fly ash and bentonite content was 20% and 11% respectively, the 28d cement-soil shear strength parameter, e.g. cohesion c, was the largest at 1144.8kPa; when fly ash and bentonite was added with the amount of 30% and 5% respectively, the cohesive force c of the 90d cement soil shear strength parameter was the largest at 1753.71kPa. The research results can provide reference for the on-site preparation of cement-soil with fly ash and bentonite in Wuhan area.

Key words:cement-soil properties; bentonite; fly ash; adding amount; compressive strength; shear strength; soil reinforcement; Wuhan area