The early unconfined compressive strength test with composite low dosage of cement red clay

• 1、Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, Hohhot 010018, China

Abstract：The red clay in the central and western regions in Inner Mongolia autonomous region was selected and the fly ash waste and polypropylene fiber as the additive agent was applied tomake a kind of special cement-soil, which is has the economic beneficial and environmental effect. The orthogonal experiment was applied to study the influence of the dosage of cement, fly ash, polypropylene fiber and mixture moisture content on 7 days early unconfined compressive strength of cement-soil. It is concluded that in a certain range, the cement content has the greatest effect , followed by the dosage of fly ash , and the influence of the dosage of polypropylene fiber and mixture moisture content is smaller. The optimal mixture ratio is: cement 10%, fly ash16%, polypropylene fiber 0.12%, mixed moisture content18%. Then SEM test demonstrated that reasonable bedding structure of the slurry and the reinforcement and consolidation effect of fiber is the reason that the strength of 9 group is higher than group 1 from the micro aspects. The stress - strain curve fitting was drawn with the 9 group block (cement content10%, fly ash 16%, fiber content0.10%, the mixed moisture content 16%). It is concluded that the rising of the curve fits the cubic polynomial equation, and the decline of the curve fits quadratic polynomial equation. The experiment results can provide certain reference for practical engineering application.

Keywords： unconfined compressive strength test red clay cement orthogonal test SEM test stress and strain