Analysis of the Mechanical Properties of Cured Sludge by Alkaline Excitation of Phosphogypsum

Engineering slag is a green building material that meets the requirements of contemporary sustainable development, and the solidification technology of residue is particularly important in the practical engineering of resource utilization and environmental protection. In order to reuse the waste soil and industrial waste and reduce the construction cost, the stabilization effect of adding different contents of calcium oxide, blast furnace slag and phosphogypsum to the waste soil of a township road reconstruction project was studied. The unconfined compressive strength test of calcium oxide further clarified the solidification mechanism of residual soil and helped us to obtain the optimal curing ratio. The dry and wet cycle test simulated the influence of temperature and humidity changes on the appearance, quality, strength and water resistance in actual engineering. The experimental results show that the unconfined compressive strength of the sample reaches 1.273 MPa after 7 days of curing when the mixture of 4% calcium oxide (ratio to 100% plain soil) and 16% blast furnace slag (ratio to 100% plain soil) is mixed. When the three materials were mixed, the unconfined compressive strength of 4% calcium oxide (the ratio of 35% phosphogypsum and 65% plain soil) and 16% blast furnace slag (the ratio of 35% phosphogypsum and 65% plain soil) reached 1.670 MPa and 3.107 MPa at 7 and 28 days, respectively. The curing age has a significant promoting effect on the stability of loess. The dry and wet cycle test results conclude that the specimens have good durability and stability. The results of microstructure analysis shows that a large number of ettringite and C-S-H gel were formed in the gelling system, which not only makes the original soil more stable, but also acts as a part of filling pores, and the two work together to support the soil and improve the strength.

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