Experimental Study On The Properties Of Cemented Soil Polluted By Paper Mill Effluent

Pollution in the project may lead to reduce foundation bearing capacity, differential settlement and other issues, and thereby affect the safety and durability of the building. When the cemented soil encounter industrial waste water, the impact of pollution has to be considered. By paper mill effluent field collection, the circumstances that the soil polluted is going to be reinforced and the cemented soil column suffers effluent drainage were simulated in the laboratory, and some conclusions were made, which may play a guiding role in the engineering practice.To investigate the effect of polluted soil on the properties of cemented soil, a number of test blocks were prepared which contained clean soil, polluted soil contaminated by 70% or 100% paper mill effluent respectively. After curing 7, 14, 28, 60, 90 days in standard curing condition, unconfined compressive strength and resistivity were measured. The test data were analyzed and the following conclusions were drawn. To ordinary portland cement and slag portland cement, when the effluent concentrations are the same, compressive strength and resistivity increase logarithmically with the increase of age; when the ages are the same, compressive strength and resistivity decrease exponentially with the increase of effluent concentration; compressive strength increases linearly with the increase of resistivity. When both age and effluent concentration are the same, the compressive strength and resistivity of cemented soil with slag portland cement are higher than those of cemented soil with ordinary portland cement. Compressive strength prediction formulae were established which based on the age and effluent concentration. To study the influence of effluent environment on the properties of cemented soil, a number of test blocks with clean soil were made, cured in standard curing condition for 7 days,and then immersed in clean water and pure paper mill effluent respectively. After immersion for 7, 14, 28, 90 days, the blocks were tested; the unconfined compressive strength and resistivity were measured. The test data were analyzed and the following conclusions were drawn. To ordinary portland cement and slag portland cement, compressive strength and resistivity of cemented soil immersed no matter in clean water or paper mill effluent increase logarithmically with the increase of immersion time; when the immersion time is the same, compressive strength and resistivity of cemented soil in paper mill effluent environment are lower than those of cemented soil in clean water environment; compressive strength increases linearly with the increase of resistivity. When both immersion time and water environment are the same, the compressive strength and resistivity of cemented soil with slag portland cement are higher than those of cemented soil with ordinary portland cement.The whole failure process of cemented soil blocks was observed and analyzed. In various conditions, the failure characteristics are almost the same and all the stress-strain curves are similar with obvious elastic phase and plastic phase.The paper also qualitatively analyzes the effect of effluent's chemical composition on the compressive strength of cemented soil. The wastewater contains many components and various physico - chemical actions coexist and interact, therefore the whole process is very complicated.