Mechanical strength characteristics of saline soil stabilized by all-solid waste cementitious material based on projection pursuit regression modeling

To reduce engineering hazards caused by saline soil, and considered from the perspectives of environmental protection and resource conservation, an all-solid waste cementitious material consisting of carbide slag (CS), fly ash (FA), and slag was designed and used to stabilize saline soils with different sulfate contents. Unconfined compressive strength (UCS) tests were conducted, and a projection pursuit regression (PPR) model was established to investigate the relationship between the waste composition and the UCS of the stabilized soil at different sulfate contents. The microstructural characteristics of the stabilized soil were explored through scanning electron microscopy–energy dispersive spectrometer (SEM–EDS), X-ray diffraction (XRD), thermogravimetric–differential thermal analysis (TG–DTA). The results showed that the dosages of pozzolanic materials (FA and slag) and sulfate content had non-negligible effects on the UCS of stabilized soils. The stabilization mechanism included the cementing effect of the volcanic ash reaction and the filling effect of ettringite (AFt). The PPR model exhibited high calculation accuracy and reflected the inherent structure of high-dimensional test data for the UCS of saline soil stabilized with the designed all-solid waste cementitious material.