Cement manufacture generates environmental problems due, among others, to the greenhouse gases, especially CO2, emitted in the process.A number of materials have been used as cement additions in recent years to lower such emissions.One of the foremost is nanosilica (nSA), which as a nano-filler and pozzolan enhances the mechanical strength and reduces the porosity of the end product.Portland cement hydration is favoured by both temperature and the presence of nSA.