Cyclic weathering effects on thermal behaviour and cracking of MgO-stabilised soils

Silty and clayey soils are particularly vulnerable to freeze–thaw and wet–dry cycles, which can accelerate structural deterioration and increase maintenance costs. Traditional stabilisers such as cement and lime raise environmental concerns, spurring research into reactive magnesium oxide (MgO) as a more sustainable alternative. This study investigates the impact of magnesium oxide on the thermal behaviour and crack evolution of silty and clayey soils subjected to 40 freeze–thaw and wet–dry cycles. Quantitative assessments revealed that untreated clayey soil showed a final surface crack ratio of 5.19%, while 10% magnesium oxide-treated clayey soil reached only 3.15%. In silty soil, the crack volume in untreated samples was 0.95 cm³, compared with 0.759 cm³ with 10% magnesium oxide. Thermal conductivity declined significantly in untreated samples to approximately 0.3 W/m·K, whereas magnesium oxide-treated soils exhibited higher resilience. Furthermore, silty soil with 10% magnesium oxide achieved superior crack closure of 15.6% – highlighting magnesium oxide’s self-healing benefits. Overall, magnesium oxide treatments markedly enhanced soil resistance against repetitive freeze–thaw and wet–dry cycles, reducing crack propagation and preserving structural integrity. These findings support the use of magnesium oxide as a viable, eco-friendly stabiliser for silty and clayey soils, delivering improved thermal stability, reduced cracking, and notable self-healing properties in harsh environmental conditions.