Abstract: A method of cementing an oil and gas wellbore is accomplished by mixing together blast furnace slag, construction grade cement and water to form a pumpable slurry. The slurry is then pumped to a selected location within an oil and gas well and allowed to solidify within the wellbore. The blast furnace slag alters the properties of the construction grade cement so that it can be used in the construction of oil and gas wells, where it would otherwise not be feasible to use. The blast furnace slag enhances the physical and chemical properties of the construction grade cement, increasing gel times and decreasing fluid loss.