Effect of wet – dry cycles on CBR value and grain size distribution particle on compacted residual tuff soil

Abstract

Uncertain climate change is a natural phenomenon that is common nowadays. Soil is the result of weathering of rocks and climate change is one of the causes of this weathering. Residual soil is soil formed on top of the original rock layer. In addition to the parent rock, climate change also affects the residual soil, both in terms of grain size and shear strength. This climate change modeling was carried out by giving wet-dry treatment on residual tuff soil samples at the Institut Teknologi Sumatera (ITERA) which were compacted with a wet-dry cycle of 2 cycles, 4 cycles, 6 cycles, 8 cycles, and 10 cycles. From this treatment, it will be seen the change in gradation and the magnitude of the CBR value. The change in grain gradation is obtained which is calculated based on the concept of grain breakage, namely the Br value in each cycle of 15.89%; 21.51%; 25.35%; 32.01%; 36.28%. For the CBR values obtained for the initial conditions and each cycle are 50.74%, 40.34%; 29.763%; 25.16%; 22.825%; 20.580%. These results indicate that the longer the cycle occurs in the soil, the greater the change in grain gradation and the CBR value of the residual tuff soil. For this reason, the wet-dry process needs to be considered for the use of residual tuff soil as the subgrade of the road pavement.