Correlating unsoaked CBR with UCC strength for SC and SP soil

Abstract

Most of the civil engineering structures are constructed on the ground and are supported by soil strata or rock strata present at the site. As soil is heterogeneous, its properties vary from one place to another within a distance of few meters. Thus it is tough to predict the behavior of soil without studying its engineering properties in detail. One of the important laboratory test that is generally conducted for the flexible pavement design is California Bearing Ratio (CBR) test. CBR test is a laborious and time consuming process and may lead to delay in execution of construction projects and thus cause increase in construction costs. Thus an effort has been made to correlate unsoaked CBR value of soil with the UCC strength of soil by Simple Linear Regression Analysis (SLRA) so that based on the UCC strength of soil unsoaked CBR value of soil can be predicted. In this project, 2 types of disturbed soil samples were collected from in and around Chennai region and were classified as Clayey Sand (SC) and Poorly Graded Sand (SP) based on the index properties of each soil. Unconfined Compression (UCC) test and unsoaked CBR test were conducted on the two soil samples by varying the moisture content (MC), to determine whether the maximum strength gain was observed on the dry side or wet side of optimum moisture content (OMC) and to study the extent of increase in UCC and CBR strength compared to control specimen (CS) prepared at OMC. From the results, it was observed that maximum strength gain was attained on the dry side of optimum.