International Journal of Science and Technology (IJST)

Temperature Induced Variations in Soil Shear Strength: Experimental Approch

This study examines the effect of elevated temperatures on the shear strength behaviour of soil within the range of 27 to 600 °C. Experimental work comprised of index property characterization, Standard Proctor compaction, direct shear testing and California Bearing Ratio (CBR) assessment. The results show that moderate heating (110–200 °C) leads to a marginal increase in cohesion, attributed to partial dehydration of clay minerals and enhanced particle interlocking. Beyond 300 °C, pronounced structural degradation occurs, resulting in a steep reduction in cohesion from 60 kN/m² at untreated to complete loss at 500 °C. Conversely, the internal friction angle increases progressively from 17° to 47° at 600 °C, indicating a shift from cohesive behaviour to a friction dominated granular response. Overall, the soil exhibits a 72% reduction in shear strength at 600 °C. Microstructural and mineralogical transformations identified through XRD, SEM and EDS corroborate these mechanical changes. The findings highlight the non-linear thermal sensitivity of soil and provide critical insights for geotechnical design in high-temperature scenarios, including fire-affected foundations, geothermal infrastructure and thermal waste containment systems.