Study On Mechanical Property Of Cemented Soil Under Sanitary Contamination

With the sustainable development of economy and the rapid industrialization and urbanization in China, the amount of the abandoned chemical from factories and domestic refuse are sharply increased, whose wastewater can pollute not only the water substance and the atmosphere, but also the soil. The soil pollution can not be ignored even in the urban plan process.The mechanical properties of cement soil mixing column that is a common method in soil improvement is influent by the environmental pollution directly and seriously. The contamination of either soil or underground water leads to reduce of the mechanical properties of the cemented soil mixed column, results in reduce of the structure's reliability and durability degree. The research of the contaminated soil has a great and practical meaning.The current researches of polluted soil are mostly related to a single chemical composition. A serious limitation for all these theoretical results is being quite different from the practical situationis.In this paper, studies have been done as follow:1 Sanitary, silty clay, two kinds of cement (normal Portland cement and slag Portland cement) are chosen to manufacture the contaminated soil-cement test blocks which are at different concentrations of the sanitary.2 Mechanical properties of cemented soil are studied by indoor simulation experiment. Physical and mechanical properties of the soil-cement are marked by the age and concentrations of the contaminating. The experimental results show that the unconfined compressive strength of the contaminated cemented soil increases linearly with the age and decreases exponentially with the increases of the contamination's content in a certain age. The predictor formula about the effect of the sanitary on the strengths of the cemented soil is established.3 The electrical resistivity of the cemented soil increases with the age time and decreases with the contamination's content; the electrical resistivity is linear with the unconfined compression strengths. This correlation may be used to predict and check the strength of soil-cement.4 The micro-structure of the soil-cement is investigated with scanning electron microscope, and data such as soil pore parameters, pore size classification parameters have been analyzed by use of Image-Pro plus 6.0 image analysis procedure. With the combination of soil physical and mechanical properties and micro-structure study, the cause of the reasons for changes in soil has been discussed.5 At last, by analyzing from the view of chemical mechanism the change of cemented soil strengths may be explained. The physical and chemical reactions between erosive chemical substances in the household wastewater and the cemented soil cause the deterioration of the physical properties, the change of the mineral component, the structural instability and erosion of the cementation.