Engineering properties of cement and lime stabilized silty sand in pavement sub bases

Chemical stabilization of soils is a widely used practice for improving engineering properties of soil. This technology is used very effectively in developed countries with standard and appropriate machinery specific to them. This study is focused on sensitivity analysis of important parameters of soil stabilization and the effect of nonstandard machinery on improving of medium plastic silty sand soil which is abundantly available in Sri Lanka. Three soil samples of silty sand with medium plasticity which do not meet the specified requirements for subbases were studied. Laboratory test results indicate that both stabilizers improve spil properties up to a considerable degree. Comparison of Unconfined compressive strength (UCS), degree of p^0m verization (DOP) and mixing time for drum mixing and rotary mixing were made and it was found that the rotary mixing provides higher UCS and DOP with a minimum number of mixing cycles. It was observed that the DOP and UCS reduce with extended mixing time in drum mixing and values slightly increase after achieving the maximum in rotary mixer. Two possible compaction scenarios (under prevailing moisture content and ojry timum moisture content relevant to the compaction time) were evaluated for both cement and lime stabilization. Furthermore, variation of the optimum moisture content (OMC) with the time was studied for cement stabilized and lime stabilized soil. Test results show that compaction time (delayed compaction), moisture content at the mixing time and moisture content at the compaction time are crucial factors that must be considered in soil stabilization with cement and lime