Experimental study on the engineering properties of expansive soil treated with Al13

Jianbo She,Zheng Lu,Liang Liu,Yahui Duan,Hailin Yao

doi:10.1038/s41598-020-70947-6

Abstract

This paper investigates the stabilization of expansive soil with hydroxy-aluminium (Al13) with Al/soil ratios of 0.10, 0.14, 0.18, 0.22 and 0.26 mmol/g. A series of laboratory tests were conducted to study the effects of Al13 on the mechanical properties of expansive soil, including Atterberg limits, grain size distribution, swell percent, swell pressure and unconsolidated-undrained (UU) triaxial strength. The results revealed that Al13 reduced the plasticity index, clay content and swelling potential and enhanced the shear strength of expansive soil. The minerals and micro-structural changes in the soil samples were also determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the stabilized soil showed a remarkable flocculated-agglomerated structure characterized by the densification of particle associations. The consistency of the changes in mechanical properties and micro-morphology indicated that expansive soil can be effectively improved with the use of Al13. Additionally, the optimum dosage of polynuclear hydroxy-Al (PHA) solution for stabilizing expansive soil was 0.18 mmol/g under the given properties of expansive soil and PHA utilized in this study.

Highlights

This paper investigates the stabilization of expansive soil with hydroxy-aluminium ( Al13) with Al/soil ratios of 0.10, 0.14, 0.18, 0.22 and 0.26 mmol/g
The results indicated that A l13 or other Al monomers were not detected in the supernatants, which illustrated that all the Al13 groups and Al monomers were adsorbed by the expansive soil in the crosslinking process and replaced the low valence cations, which led to the modified effects
The liquid limit and plasticity index of the samples decreased as the Al/soil ratio increased, whereas the plastic limit decreased slightly

Summary

Introduction

This paper investigates the stabilization of expansive soil with hydroxy-aluminium ( Al13) with Al/soil ratios of 0.10, 0.14, 0.18, 0.22 and 0.26 mmol/g. The consistency of the changes in mechanical properties and micro-morphology indicated that expansive soil can be effectively improved with the use of Al13. Hydroxy-aluminium with the stoichiometry [ AlO4Al12(OH)24(H2O)12]7+ (Al13) as an Al species in a polynuclear hydroxy-Al (PHA) solution has been considered to be a desired intercalator and chemical stabilizer for swelling clay m inerals[18,19,20]. This Al13 polymer is the primary component of intercalated Al adsorbed in the crystal layer to form thermally stable pillaring c lay[21]. The physical changes of stabilized and natural samples were studied by Scientific Reports | (2020) 10:13930

Methods

Results

Discussion

Conclusion