The quality of road pavements is an important factor to ensure an acceptable level of service and safety to the road users. When flexible road pavements are to be constructed on weak sub-grade soils, it is often necessary to provide a stabilised sub-base to improve their relevant engineering properties. This paper presents the results and observations from a laboratory investigation evaluating the compaction properties of road sub-base stabilised with Type I cement (ordinary Portland cement) and styrene-butadiene latex copolymer. The proposed polymer contents were 0.5%, 0.75%, 1% and 2% and the proposed cement contents were 2%, 3% and 5%. The 2.5kg rammer compaction test was conducted on the gravelly SAND and sandy GRAVEL samples. It was found that the maximum dry densities (MDD) for the untreated soil samples were higher than the cement-polymer-treated soil samples, indicating that the MDD values decrease when cement and polymer are added. The MDD values for gravelly SAND and sandy GRAVEL treated with cement-polymer lied between 2Mg/m3+0.03Mg/m3 and 2.09Mg/m3+0.04Mg/m3 respectively. The optimum moisture contents for gravelly SAND and sandy GRAVEL treated with cement-polymer were maintained at 9%+0.5%. The air void lines for gravelly SAND and sandy GRAVEL lied between 7%+1% and 3%+1% respectively.