STABILISATION OF TROPICAL SOIL WITH HYDRATED LIME AND PLASTIC BLEND

Abstract

Effective utilization of locally available deficient soils by imparting additional strength using stabilising agents enable reduction in construction cost and improved performance for engineering projects. This work focuses on stabilisation of lateritic soil with hydrated lime and plastic blend using appropriate additions. The tests were carried out in accordance with the test procedures specified in BS 1377: 1992. This is done to determine the effect of the additives on the index and engineering properties of the treated soil being tested. From the results, the soil was classified as A-7-6 and CL according to AASHTO and USC systems respectively. It is a poorly drain soil with a liquid limit of 47% and requires a form of stabilisation before it could be used for construction purpose. On treatment with the blend of the additives, the plasticity index of the soil reduced from 20.86 to as low as 1 at 6% lime + 3% plastic blend. It then increased to 2.2 at 6% lime + 4% plastic blend. On the compaction, there was an overall increase in the OMC from 15.3% to 19.5% and a decrease in the MDD from 1.92 g/cm3 to 1.71g/cm3 at 6% lime + 4% plastic blend. CBR result shows that there was a significant increase in the CBR value from 6.04% to 57.03% at 6% lime + 1% plastic blend and then decreased to 12.61% at 6% lime + 4%plastic blend. For the strength test, there was an increase from 388.4 kN/m2 to a maximum UCS value of 792.2 kN/m2 at 4% lime + 1% plastic blend additive without curing. The UCS value increased to 1397.24kN/m2 at 4% lime + 1% plastic blend after 7 days curing, which satisfied the specification in Highway manual, Federal Ministry of Works. After curing the samples for 28 days, the maximum UCS obtained was 1723.2 kN/m2 at 4% lime + 2% plastic blend from the UCS test after curing for 28 days.