Abstract Semi-flexible pavement has a more notable advantage over asphalt concrete pavement in terms of rutting performance. Cement grouting and open-graded asphalt concrete are components of the semi-flexible pavement. In cement grouting, two commercial modifiers from Sika Vietnam were used, Sika Latex and Sika TH Latex, with different contents from 4.5% to 7.5% for Sika Latex and 7.5% to 9.5% for Sika TH Latex. 72 samples of cement mortar were fabricated in laboratory conditions from PCB40. All cement grouts were cured at the age of 7 days. The paper results focus on the flexural strength and the compressive strength of both mortars, the suggestion of Sika content to produce the stable strength of cement grout, and the viscosity of cement mortar based on the Sika contents.