Relationship between liquidity index and stabilized strength of local subgrade materials in a tropical area

This paper presents the effect of soil liquidity index and cement stabilizer on strength properties for the usage of low traffic volume subgrade roads. Three types of soil were used to represent a different soil based on liquid limit value. Standard proctor tests have been conducted to determine the Optimum Moisture Content (OMC) and Maximum Dry Density (MDD) of stabilized soils with 0%, 7%, and 13% Ordinary Portland Cement (OPC). In order to study the effect of the soil Liquidity Index, various moisture contents are used based on the OMC value from the compaction test (0.9, 1.0, and 1.1 from OMC). The California Bearing Ratio (CBR) and Unconfined Compressive Strength (UCS) tests were conducted to determine the strength of all soil samples at optimum moisture content after 7 days curing period. It has been observed that the CBR and UCS values increased by increasing the percentage of cement content. This study found that 7% of cement content was the optimum percentage of cement content to be added to all tested soils to achieve the minimum required strength of 0.8 MPa and 80% CBR for low traffic volume roads. The presented results could provide a guideline for engineers as regards the property changes of the local subgrade materials in a tropical area due to the addition of cement content.