Cement Soil Strength Properties

The in situ mixing technique is an established means of enhancing bearing capacity and reducing settlement by cement and clay entering into physicochemical interaction with fluid and getting hardened continuous non-particulate material. The product is called cement soil and fit for treating soft clay, super soft clay,silty clay, gravcl soil, soil aggregate and so on.The main strengthening reasons of cement treated soil are aggregating, concreting, original soil improvement, carbonating and crystallization. The main factors of influencing strength are quasi-cement-content, quasi-water-content, curing time and so on.Physical characteristics of soft clay in suit have been assumed first. Then a series of laboratorial triaxial shear tests were performed on reconstituted Liyang clay (Zheng-Li highway, Jiangshu province) proportional mixed with powder cement to investigate the strength and modulus behaviors of cement soil. According to the orthogonal analysis of strength test results, it is revealed that the most effective factor of strength is quasi-cement-content, the next one is curing time and the last is quasi-water-content. The interaction of quasi-cement-content and quasi-water-content is obvious, according to binary variance analysis. A concept of water-cement-weight ratio is proposed for predicting the strength of cement soil. The strength empirical formula based onquasi-water-cement-ratio and quasi-cement-content can be used for predicting the change in strength with variation of quasi-cement-content, quasi-water-content and curing time. The empirical formula can be also applied for the test data from other researchers, further indicating the validity.The strengthening theory of cement soil is testified by SEM results and chemical component analysis. The cement content changing behavior in cement soil is revealed by cement content determination test, based on the SEM results and chemical component analysis.