A method for the production of an alkali activated hydraulic binder, with the binder comprising slag, natural aluminum silicates, and an alkali activator, and the binder being free of CaSO4. The slag is provided in amounts greater than or equal to 20% (w/w), and the natural aluminum silicates are different from furnace slag, and are provided in amounts from 5 to 75% (w/w). The alkali activator is provided in an amount which corresponds to a Na2O equivalent defined as (Na2O+0.658 K2O) (ASTM C 150) between 0.7 and 4% (w/w). The method includes the step of heat treating a mixture of the slag, the natural aluminium silicates, and the alkali activator at temperatures between 40° C. and 50° C. for 4 to 6 hours.