EFFECTS OF ORDINARY PORTLAND CEMENT ON THE SOIL-WATER CHARACTERISTICS CURVE OF LATERITIC SOIL

The lateritic soil, abundant in tropical and sub-tropical countries, is a common construction material used for various purposes, such as constructing transportation infrastructures, landfills, and other earthworks. The residual lateritic soil is usually located in the vadose zone (unsaturated zone) situated above the water table. Therefore, this paper investigates untreated and cement-treated lateritic soil behaviour in terms of Soil Water Characteristics Curve (SWCC), a key topic in unsaturated soil mechanics. The soil sampling was performed from Universiti Teknologi Malaysia campus, Johor Bahru, and then the collected soil was tested in the laboratory. The 3%, 6%, 9%, and 12% ordinary Portland cement (OPC) according to the dry soil weight were utilized, and then the necessary basic tests, compaction tests, and pressure plate tests were performed. The obtained data points from pressure plate extractor equipment were fitted using Fredlund and Xing and van Genuchten models. The results exposed that the used soil is plastic silt (MH) and A7-5 according to the Unified soil classification System (USCS) and AASHTO, respectively. The Maximum Dry Density (MDD) increased from 1.39 g/cm3 for untreated to 1.419 g/cm3, 1.447g/cm3, 1.46g/cm3, and 1.479g/cm3 for 3%, 6%, 9%, and 12% cement, respectively. Similarly, the Optimum Water Content (OMC) increased from 28% to 29.5, 30, 30.5, and 31% by adding 3, 6, 9, and 12% cement, respectively. Regarding the obtained SWCC results, the Air Entry Value (AEV) increased with the increasing cement content. Overall, the results revealed that the water holding capacity of lateritic soil increases with increasing cement content.