Mechanical-Cement Stabilization of Laterite for Use as Flexible Pavement Material

An attempt was made to improve the physical and strength properties of a reddish-brown lateritic soil. 15–60% of sand by dry weight of laterite was used as a modifier in the stabilization of the laterite with 3–12% by dry weight of cement. Classification, compaction, California bearing ratio (CBR), and unconfined compressive strength tests were carried out on the specimens. The plasticity index decreased from 17% for untreated laterite to 2.5% when treated with a combination of $60\mathrm{\%}\text{sand}+6\mathrm{\%}\text{cement}$ . For the two energy levels of compaction, optimum moisture content (OMC) was found to increase with an increase in cement content but decreased as the sand content increased. The OMC at the West African standard (WAS) energy level was consistently lower than the values obtained at the standard proctor (SP) energy level, while the corresponding values of maximum dry density were higher at the WAS energy level than the values at the SP energy level. The CBR requirements for base course material were met when laterite was admixed with $45\mathrm{\%}\text{sand}+6\mathrm{\%}\text{cement}$ and $30\mathrm{\%}\text{sand}+6\mathrm{\%}\text{cement}$ , and $15\mathrm{\%}\text{sand}+6\mathrm{\%}\text{cement}$ , $30\mathrm{\%}\text{sand}+6\mathrm{\%}\text{cement}$ , and $45\mathrm{\%}\text{sand}+3\mathrm{\%}\text{cement}$ at the SP and WAS energy levels, respectively. It can be concluded that sand enhanced the effective stabilization of Ikpayongo laterite with cement within the maximum cement content specified by the Nigerian code.