Han Youmin, Xia Junwu, Chang Hongfei, Xu Jun
State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Daxue Road, Xuzhou 221116, China.
School of Architecture and Civil Engineering, Anhui Polytechnic University, Beijing Road, Wuhu 241000, China.
Materials (Basel). 2021 Mar 11;14(6):1359. doi: 10.3390/ma14061359.
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.
为揭示钙矾石（AFt）晶体及微观结构特征对钙基稳定土强度的影响机制，通过无侧限抗压强度、扫描电子显微镜（SEM）、X射线衍射（XRD）、热重分析（TG）和傅里叶变换红外光谱（FTIR）测试方法，系统研究了七组稳定土样品的强度和微观特性。结果表明，水泥稳定土强度较高，因为大量水化硅酸钙（CSH）凝胶包裹在土颗粒外表面，使其胶结在一起。对于水泥-石膏稳定土，过多的粗大且长的AFt晶体使土颗粒中的孔隙变大，样品变得疏松，导致强度低于水泥稳定土。然而，水泥-石膏-石灰稳定土的强度略高于水泥稳定土，原因是适量的细小AFt晶体填充了土颗粒间的大孔隙，形成网络空间结构，且充足的CSH凝胶将土颗粒与AFt晶体网络空间结构紧密胶结在一起。可以认为，钙基稳定剂的组分应考虑CSH凝胶与细小AFt晶体之间的最佳生成平衡。
