Study on the Optimal Ratio of Cement Coal Fly Ash Improved Saline Soil
[Purposes]On the basis of traditional cement improved soil,fly ash is added to improve saline soil.Fly ash solidified saline soil is in line with the goal of"double carbon"goal,which has positive sig-nificance.[Methods]A three-factor and four-level orthogonal test was designed to analyze the effects of cement fly-ash content,curing conditions and water content on the compressive strength and elastic modulus of the sample.The fixed proportion of cement fly ash is controlled to be 1∶2,the content t levels are 12%,14%,16%,18%,and the curing methods are clean water,salt water,high temperature curing and standard curing.[Findings]The compaction test showed that the content of cement fly-ash had little effect on the maximum dry density within the test range,the maximum dry density was about 1.8 g/cm3,and the optimal water content was between 14%and 16%.The improved soil shows strain softening type.The highest compressive strength is 1.69 MPa and 1.99 MPa,and the smallest compressive strength is 0.34 MPa and 0.55 MPa at 7 d and 14 d ages.[Conclusions]The strain softening characteristics are ob-vious with the increase of dosage and the deepening of reaction and hydration degree of volcanic ash.The amendment content is 18%,the moisture content is 16%,and the strength is the highest when the curing method is high temperature curing.The strength of saline soil is the largest when the dosage of modifier is 18%,the moisture content is 16%,and the curing method is high temperature curing.The order of the influence of the three factors on the strength of saline soil is curing condition>modifier dosage>moisture content.The weight of the factors is 57%of curing condition,24%of modifier dosage and 19%of moisture content.The compressive strength and resilient modulus are fitted,and it is found that there is a good linear relationship between them.
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