Effect of palm oil on the basic geotechnical properties of kaolin

This paper presents an experimental study to evaluate the effect of palm oil on the selected basic physical-chemical and geotechnical properties of kaolin. The experimental findings are further compared with literature outcomes investigating similar properties of fine grained soils subjected to contamination by different types of oils. To this end, palm oil was mixed with oven dried kaolin samples–aiding oil\'s interaction (coating) with dry particles first, in anticipation to emphasize the effect of oil on the properties of kaolin, which would be difficult to achieve otherwise. Oil content was limited to 40% by dry weight of kaolin, supplemented at intervals of 10% from clean kaolin samples. Observations highlight physical particle-to-particle bonding resulting in the formation of pseudo-silt sized clusters due to palm oil\'s interaction as evinced in the particle size distribution and SEM micrographs. These clusters, aided by water repellency property of the oil coating the kaolin particles, was analyzed to show notable variations in kaolin\'s consistency–measured as liquid and plastic limits. Furthermore, results from compaction tests indicates contribution of oil\'s viscosity on the compaction behavior of kaolin – showing decrease in the maximum dry unit weight (gammad,max) and optimum moisture content (wopt) values with increasing oil contents, while their decrease rates were directly and inversely proportional in gammad,max and wopt values with oil contents respectively. Comparative study in similar terms, also validates this lower and higher decrease rates in gammad,max and wopt values of the fine grained soils respectively, when subjected to contamination by oil with higher viscosity.