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<p>The water retention capacity of swell-shrink soils is significantly influenced by temperature, yet the underlying microscopic mechanisms remain poorly understood. This study investigates two widely distributed swell-shrink soils in southern China—expansive soil and lateritic clay—by measuring soil–water retention curves (SWRCs) at varying temperatures (5–60&#xa0;°C) using the filter paper method, complemented by bound water determination, mercury intrusion porosimetry (MIP), and scanning electron microscopy (SEM). The results revealed that temperature significantly reduces water retention capacity only when matric suction falls below a critical threshold (<i>S</i><sub>c</sub> = 40&#xa0;MPa for expansive soil; <i>S</i><sub>c</sub> = 10&#xa0;MPa for lateritic clay), with the volumetric water content of expansive soil decreasing by 41.4% at 60&#xa0;°C, compared to 16.3% for lateritic clay. This phenomenon was attributed to the desorption of weakly bound water, which linearly decreased with rising temperature (<i>R</i><sup>2</sup> &gt; 0.96), showing a reduction of 11.59% in expansive soil (2.3 times higher than lateritic clay’s 5.08%) due to its higher content of hydrophilic minerals like montmorillonite and illite. Furthermore, MIP and SEM analyses demonstrated that elevated temperatures compress inter-aggregate pores (reducing pore size by 6.18&#xa0;μm in expansive soil and 3.69&#xa0;μm in lateritic clay) while slightly increasing intra-aggregate pores, accompanied by shrinkage of interlayer spacing in clay minerals. By systematically linking bound water dynamics, pore structure evolution, and micromorphological changes, this study provides the first multiscale mechanistic explanation of temperature-dependent water retention in swell-shrink soils, offering critical insights for geotechnical applications such as roadbeds and landfill liners in high-temperature environments.</p>

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Microscopic mechanism analysis of temperature dependence on swell-shrink soils water retention capacity

  • 期刊论文

  • 发表日期：

    2025年3月20日

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  • Zheqi Cui,
  • Zhaotian Zeng,
  • De’an Sun

摘要

The water retention capacity of swell-shrink soils is significantly influenced by temperature, yet the underlying microscopic mechanisms remain poorly understood. This study investigates two widely distributed swell-shrink soils in southern China—expansive soil and lateritic clay—by measuring soil–water retention curves (SWRCs) at varying temperatures (5–60 °C) using the filter paper method, complemented by bound water determination, mercury intrusion porosimetry (MIP), and scanning electron microscopy (SEM). The results revealed that temperature significantly reduces water retention capacity only when matric suction falls below a critical threshold (Sc = 40 MPa for expansive soil; Sc = 10 MPa for lateritic clay), with the volumetric water content of expansive soil decreasing by 41.4% at 60 °C, compared to 16.3% for lateritic clay. This phenomenon was attributed to the desorption of weakly bound water, which linearly decreased with rising temperature (R2 > 0.96), showing a reduction of 11.59% in expansive soil (2.3 times higher than lateritic clay’s 5.08%) due to its higher content of hydrophilic minerals like montmorillonite and illite. Furthermore, MIP and SEM analyses demonstrated that elevated temperatures compress inter-aggregate pores (reducing pore size by 6.18 μm in expansive soil and 3.69 μm in lateritic clay) while slightly increasing intra-aggregate pores, accompanied by shrinkage of interlayer spacing in clay minerals. By systematically linking bound water dynamics, pore structure evolution, and micromorphological changes, this study provides the first multiscale mechanistic explanation of temperature-dependent water retention in swell-shrink soils, offering critical insights for geotechnical applications such as roadbeds and landfill liners in high-temperature environments.