Study on the optimization and performance of GFC soil stabilizer based on response surface methodology in soft soil stabilization

In order to improve the utilization efficiency of industrial waste residue and the treatment effect of marine soft soil, ground granulated blast furnace slag (GGBS), flue gas desulfurization gypsum (FGDG) and calcium carbide slag (CCS) were used to modify the waste soft soil in coastal areas. Using the box-behnken design (BBD) in response surface analysis, the optimal mix ratio design of GGBS, FGDG and CCS was obtained. Meanwhile, under the same conditions, the mechanical properties, durability and micro mechanism of industrial waste residue stabilized soil was studied and compared with that of OPC stabilized soil by the unconfined compressive strength (UCS) test, water stability test, freeze–thaw cycle test, X-ray diffraction and scanning electron microscope (SEM) test. Experimental results showed that the optimal mixing ratio of GGBS, FGDG and CCS was 61: 8: 31; the UCS of GFC stabilized soil exceeded 8.7 MPa at 28d. The UCS of GFC stabilized soil at 28d was 1.23 times higher than that of OPC stabilized soil. GFC stabilized soil also possessed superior durability than OPC stabilized soil. Micro mechanism analysis showed that gel hydration products (CSH, CAOH) and expansive hydration product (AFt) were produced in GFC stabilized soil. These hydration products led to the aggregation and condensation of soil particles, which made the soil structure denser through bonding and filling effects, thus increased strength of stabilized soil.