Experimental Study on The Effect of Cement-Lime Double Admixture on Dewatering and Strength of Sludge

Abstract

Abstract Cement and lime are mixed into the sludge in different ratios to analyze the effect of curing agent on sludge dewatering and the dehydration rate, improve the strength of sludge, and promote the application of sludge in water conservancy and geotechnical engineering. The solidified sludge was subjected to test of moisture content and direct shear test to study the dewatering effect and strength characteristics of the improved soil. It was found that the precipitation and dehydration rate of solidified sludge were related to the ratio of curing agent incorporation. The higher the incorporation ratio is, the more obvious the dehydration effect is, and the maximum reduction value of dehydration is 13%. The sample’s dehydration rate is from the large to the small, and the average precipitation rate of 0-12h is 2-6 times than that of 12-72h. With the increase of the dosage of curing agent, the cohesion of solidified soil increases obviously, and its range of variation is between 32 and 77kPa. The internal friction angle of the sample increases with the increase of cement content, but fluctuates slightly under the action of lime. After comprehensive consideration of dehydration effect, shearing strength parameters and economic benefits, the optimal ratio of cement and lime to modified sludge soil can be controlled at 10% and 10%, respectively.