Mechanism of Rapid Solidification Sludge with Soil Stabilizer Based on Calcium Sulfoaluminate Cement

In this study, a composite rapid soil stabilizer (CRSS) was developed based on a calcium sulfoaluminate cement (CSA) to enhance the rapid solidification performance of sludge soil and augment its deficient engineering properties. The appropriate admixture type and dosage were determined through a double mixing test, and the stabilizer formula was optimized via response surface analysis. The solidification products and micromorphology were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the solidification mechanism was discussed. The results showed that the unconfined compressive strength (UCS) of the CRSS-solidified sludge cured for 1 day reached 9 MPa, which was approximately 5 times higher than that of sludge solidified by early strength composite portland cement (PC 42.5R). Gypsum, lithium salt, and ionic soil stabilizer addition significantly affected the strength of the CSA-solidified sludge.