Pore forming and set accelerating building material additive and process for making the same

Binder building additive contains oxides of aluminum. magnesium, silicon, iron, calcium, sodium and potassium, aluminum nitride, metallic particles and minerals. Binder building additive contains (in wt.%) 50-90 alumina (Al2O3), 4-20 magnesium oxide (MgO), 0.5-15 silica (SiO2), 0.1-5 aluminum nitride (AlN), 0.1-5 iron (III) oxide (Fe2O3), 0.1-5 calcium oxide (CaO), 0.1-5 fluorine (F), 0.1-5 sodium oxide (Na2O), 0.1-2 potassium oxide (K2O), and as metallic particles 0.1-10 aluminum (Al), 0.1-3 silicon (Si), 0.1-3 iron (Fe), and mineral components in the form of corundum and spinel (MgO.Al2O3). The metallic aluminum particles are encapsulated by mineral transition modifications of aluminum hydroxide to alpha -aluminum oxide. The additive has a particle size of at least 90% less than 500 mu m and a BET surface area of at least 10 m /g. An Independent claim is also included for a process for the production of a binder building additive. Preferred Features: The encapsulation of the mineral transition modifications has a permeability for gases and aqueous liquids. The additive has a particle size of at least 90% less than 200 mu m and a BET surface area of 10-50 m /g.