Stability Percentage Difference of Cement Stabilized Cohesive Soil using Duncan’s Multiple Range Test

Abstract

The stability percentage difference between varied cement mix proportions in the stabilization of cohesive soil is assessed in this study using Duncan’s Multiple Range Test (DMRT), a post-hoc statistical analysis technique. The aim is to evaluate and compare the means of various cement percentages to see if there are significant differences in their ability to stabilize cohesive soil based on compression strength. A range of laboratory tests, including those that measured the cohesive soil's moisture content, specific gravity, Atterberg limit, and particle size distribution, were used to initially characterize the soil. To assess the stability of the cohesive soil modified with cement at varying proportions of 5%, 10%, 15%, 20%, and 25%, three (3) trials of Unconfined Compression Strength (UCS) test were conducted taking into consideration the UCS results at depths 0.5m, 1.0m, 1.5m, 2.0m, and 2.5m. For the first trial, the result showed that the compression strength increased from 71.54 (0% cement content) to a peak of 165.88 kN/m² (20% cement content) and then further addition of cement of 25% caused a decrease to 142.16 kN/m² at 0.5m depth. The unconfined compression strength for the other depths of 1.0m, 1.5m, 2.0m, and 2.5m at the various mix proportions of 5%, 10%, 15%, 20%, and 25% for other trials followed the same trend respectively. The UCS results were further analysed using DMRT to compare the means of the three (3) trials’ UCS results to ascertain if there are significant differences between them. It was revealed that except for 5% cement content and the natural cohesive soil, 20% cement addition does not differ significantly from the rest cement addition at the 5% level of significance. Whereas the 25% cement addition does not differ significantly from 15%, 10%, and 5% cement addition; it differs significantly from the natural cohesive soil. There was no significant difference between 15% cement addition with 10%, 5% cement addition, and the natural cohesive soil. 10% cement addition does not differ significantly from 5% cement addition and the natural cohesive soil. Finally, there was no significant difference between the 5% cement addition and the natural cohesive soil at the 5% level. Based on the test results, DMRT is suitable for the determination of significant differences between varying mix proportions of cement for the stabilization of cohesive soil concerning stability.