The effects of coconut shell ash admixed with lime in variation to curing time for road construction

Abstract

Poor subgrade soil conditions might cause insufficient pavement support and shorten the life of the pavement. The addition of chemical or cementation additives to subgrade soils can help pavement to perform better. Chemical additives can be anything from waste to manufactured components like lime and coconut shell ash (CSA). These additives can be used to improve the qualities of a of soils. The efficiency of these additives is determined by the type of soil treated and the amount of additive used. Therefore, this research investigated the properties of expansive clay soil when stabilized by lime and CSA. The physical properties tests were carried out on the natural soil sample for identification and classification; and later, the mechanical properties tests were performed on the soil sample namely California Bearing Ratio (CBR). All the tests were performed in accordance to BS 1377 (1990). The soil sample was added with lime in a constant quantity of 6%, while CSA was added in proportions of 2%, 4%, 6%, and 8% from the total weigh of admixed sample. The constant lime percentage of 6% was used for stabilization as it recorded the highest CBR value during testing. The highest percentage of lime-CSA mixture was achieved at Variation 2 (6% lime + 4% CSA) for 4, 7, and 28 days as the highest value of soaked CBR was observed at this stage. Thus, it is proven that treating expansive soil with CSA combined with lime enhances it strength.