Pastes of waste glass (WG) and metakaolin (MK) were prepared by chemical activation with sodium silicate solutions of modulus Ms = 0.5, 0.75, 1 and 1.25 adjusted with sodium hydroxide. An experimental design was carried out using the Taguchi method. The compressive strength (CS) was followed for up to 120 days and then 4 selected formulations of the higher CS were further characterized by X-ray diffraction and scanning electron microscopy. The results showed that the CS depends on the experimental conditions of %WG, %Na2O and Ms and showed a maximum of 70 MPa after 120 days for the paste with 100%WG (%wt.), 8% Na2O and Ms=1.25; while a Portland cement specimen cured at 20°C reached 43MPa. The WG is more reactive than the MK under less alkaline conditions. The features of the microstructures varied notably with the %WG; however all showed relative dense matrices of reaction products, in agreement with the CS attained.