The influence mechanism of ettringite crystals and microstructure characteristics on the strength of calcium‐based stabilized soil

Abstract

To reveal the influence mechanism of ettringite (AFt) crystals and microstructure characteristics on the strength of calcium‐based stabilized soil, the strengths and microscopic properties of seven groups of stabilized soil samples were studied systematically through unconfined compressive strength, scanning electron microscope (SEM), X‐ray diffraction (XRD), thermogravimetry (TG), and Fourier transform infrared spectroscopy (FTIR) testing methods. The results indicate that the strength of the cement‐stabilized soil is relatively high because abundant calcium silicate hydrate (CSH) gels coat the outer surface of soil particles to cement together. For the cement–gypsum‐stabilized soil, superabundant thick and long AFt crystals make the pores in soil particles larger, and the sample becomes looser, resulting in lower strength than that of the cement‐stabilized soil. However, the strength of the cement–gypsum–lime‐stabilized soil is slightly stronger than that of the cement‐stabilized soil, for the reason that the appropriate amount of fine AFt crystals fill the macropores between soil particles to form a network space structure and sufficient CSH gels cement the soil particles and the AFt crystals network space structure tightly together. It could be suggested that the components of calcium‐based stabilizer should consider the optimal production balance between CSH gels and fine AFt crystals.