Abstract
Phase change materials (PCMs) can store large amounts of energy in latent heat and release it during phase changes, which could be used to improve the freeze-thaw performance of soil. The composite phase change material was prepared with paraffin as the PCM and 8% Class C fly ash (CFA) as the supporting material. Laboratory tests were conducted to reveal the influence of phase change paraffin composite Class C fly ash (CFA-PCM) on the thermal properties, volume changes and mechanical properties of expansive soil. The results show that PCM failed to establish a good improvement effect due to leakage. CFA can effectively adsorb phase change materials, and the two have good compatibility. CFA-PCM reduces the volume change and strength attenuation of the soil, and 8 wt.% PCM is the optimal content. CFA-PCM turns the phase change latent heat down of the soil and improves its thermal stability. CFA-PCM makes the impact small of freeze-thaw on soil pore structure damage and improves soil volume change and mechanical properties on a macroscopic scale. In addition, CFA-8 wt.% PCM treated expansive soil has apparent advantages in resisting repeated freeze-thaw cycles, providing a reference for actual engineering design.
Highlights
Expansive soil, extensively distributed worldwide, is a highly plastic clay rich in hydrophilic solid minerals, such as montmorillonite and illite [1,2]
It is prone to expansion and contraction deformation because of changes in external temperatures, which will cause the destruction of the soil structure and the sharp weakening of shear strength
It can be found that the maximum content of paraffin in C fly ash (CFA)-Phase change materials (PCMs) that does not leak is between 8% and 10%
Summary
Extensively distributed worldwide, is a highly plastic clay rich in hydrophilic solid minerals, such as montmorillonite and illite [1,2]. It is prone to expansion and contraction deformation because of changes in external temperatures, which will cause the destruction of the soil structure and the sharp weakening of shear strength. It is a typical “cancer soil” in the engineering field [3,4]. To reduce the impact of freeze-thaw (F-T) cycles on the deterioration of expansive soils, chemical agents such as lime [8] and cement [9,10] are usually selected as curing agents. Their reaction with water and soil particles changes the structure and composition of the soil, which can reduce the water
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