Experimental Study Of The Physical And Mechanical Properties Of Cement Reticulate Red Clay

Almost all researches on cement soil were carried on soft soil and ground of low bearing capacity. There are applications of cement soil in the areas with good soil properties, while, most of them basing on the reseach results on soft soil. Little advantage of the good soil properties were taken in this condition. As a result, not only are the function of formation may be losed, but also the construction costs and waste will be increased. For this problem, compacted cement soil properties in the Chang Sha region were investigated through a large number of laboratory tests in the article.The research status, development and applications of cement soil are introduced in this paper, also, a series of tests on cement soil in the Chang Sha region are conducted. The main conclusions are the following.1) The physical properties and indexes of the reticulate red clay were setted, like water content (ω) was 26.4%, density (p) was 1.85g/cm3; plastic limit (ωp) was 21.5%; liquid limit (ωs) was 34.7%, the most good water content (ω) was 21.7%, and maximum dry density (p) was 1.533g/cm3.2) The results of the compressive strength and shear strength test for cement soil showed that:①the strength of cement soil increased when the cement ratio increased;②the strength of cement soil decreased when the water content increased;③the strength of cement soil increased when the curing age improved, but in the late, the growth rate decreased;④the strength of cement soil increased as the strain rate increasing. The best formula of cement soil was got, such as cement ratio is 20%, the water content was setted by 40% cement weight add to 21.7% soil weight, and the curing period was 28 days.3) The results of the unconsolidated and undrained strength test show that the greater the loading rate, the greater the strength of cement. When the growth rate of the main stress increases, the loading rate increase in the initial stage of loading; when the cement ratio decreased, the loading rate effect of cement soil increased; when the water content was less than the optimum water content, the water content rate decreased, and the effect of loading rate increased; when the water content was greater than the optimum water content, water content rate increased, and the effect of loading rate increased.4) The sample of cement soil with small cement ratio failed plastically in the tests. As the increasing of the cement ratio, the plastic failure changed to brittle fracture.5) The results of the tests for a series of permeability tests showed that:the permeability coefficient of the original soil was 2.80×10-6cm/s; the permeability coefficient of soil with a same water content of the original soil was 1.35×10-7cm/s; and the permeability coefficient of cement soil with a best formula wass 2.70×10-8cm/s; optimal formulation of the cement soil permeability was 4.88×10-8cm/s. The impermeability of the original soil was the worst, the impermeability of the cement soil was the best, and the impermeability of the undisturbed soil was better than the original soil.