The well-known accelerating effect of mineral salts on the hydration of alite, the main component of portland cement is revisited in this work.The objective of this study is to identify the mechanisms leading to the acceleration of the hydration and the origin of the ion specificity.The effects of four calcium salts, calcium chloride, bromide, iodide and nitrate and of four alkali salts, sodium and potassium chloride and nitrate are investigated in concentration range of 0.1-0.5 mol of anion/L.