Study on performance of sulphoaluminate cement-based double liquid grouting material based on response surface method

In order to improve the early strength of traditional double liquid grouting material and accelerate the setting time of slurry after double liquid mixing, using fly ash, quicklime and hydrated lime to modify traditional double liquid grouting materials, sulphoaluminate cement-based double liquid grouting material (SACDL) was developed based on response surface method (RSM). Taking the mass fraction of fly ash, quicklime and hydrated lime as variables, slurry fluidity, setting time, flexural and compressive strength as responses, and a polynomial model was established, and the early hydration mechanism was analyzed in combination with macroscopic properties and microscopic morphology. The results show that the optimal mass fraction of fly ash, quicklime and hydrated lime in SACDL is 0%, 10.6% and 10% respectively, at this time, the fluidity, initial setting time, 3 h flexural strength and 3 h compressive strength of SACDL reach 141.5 mm, 19.4 min, 2.3 MPa and 12.6 MPa respectively, the error between the predicted value and the actual value is small, and the model is in high agreement with the actual data; the interaction between quicklime and hydrated lime had significant effects on the fluidity, setting time, flexural strength and compressive strength of SACDL paste at different ages, quicklime and hydrated lime greatly increased the concentration of Ca²⁺ in the liquid phase, and provided an alkaline environment for the reaction system, accelerating the hydration of dicalcium silicate (C₂S) and tricalcium silicate (C₃S), thereby improving the early strength of SACDL; however, fly ash is not suitable for SACDL, the incorporation of fly ash makes SACDL lack sufficient active silicate, resulting in a decrease in the production of ettringite (AFt), thereby reducing the strength of SACDL.