Disclosed is a method of fabricating a construction element, the method comprising the manufacturing of a construction element including a slag, wherein the slag is comprising, on a dry basis and whereby the presence of a metal is expressed as the total of the metal present as elemental metal and the presence of the metal in an oxidized state,



a) at least 7% wt and at most 49% wt of iron, Fe,
b) at most 1.3% wt of copper, Cu,
c) at least 24% wt and at most 44% wt of silicon dioxide, SiO2,
d) at least 1.0% wt and at most 20% wt of calcium oxide, CaO,
e) at least 0.10% wt and at most 1.50% wt of zinc, Zn,
f) at least 0.10% wt and at most 2.5% wt of magnesium oxide, MgO, and
g) at most 0.100% wt of lead, Pb.




Further disclosed are improved construction elements comprising the slag.