Construction castable material with controllable flow or slump comprising (a) a binder comprising fly ashes comprising from 1.5% to 35% by weight of CaO and a Lost on Ignition (LOI) value from 0.5% to 5.5% by weight, representing from 10% to 60% of the binder weight and ground granulated blast furnace slag comprising from 40% to 70% by weight of CaO and from 30 to 60% by weight of SiO2, representing from 40% to 90% of the binder weight, (b) an activator comprising alkaline reagents selected from the group composed by water glass, preferably in solution with 30 to 50% by weight solid content, sodium metasilicates and sodium hydroxide, (c) sand, fine and coarse aggregates and (d) organic acids or conjugated salts of organic acids in a dosage from 0.001% to 3% by weight with respect to the binder.

A construction composition comprises a) a cementitious binder comprising one or more calcium silicate mineral phases and one or more calcium aluminate mineral phases; b) optionally, an extraneous aluminate source; c) a sulfate source; d) an ettringite formation controller comprising (i) glyoxylic acid, a glyoxylic acid salt and/or a glyoxylic acid derivative; and (ii) at least one of a borate source and a carbonate source; and e) a polyol in an amount of 0.2 to 2.5 wt.-%, relative to the amount of cementitious binder a). The composition contains 0.05 to 0.2 mol of total available aluminate, calculated as Al(OH).sub.4.sup., from the calcium aluminate mineral phases plus the optional extraneous aluminate source, per 100 g of cementitious binder a); and the molar ratio of total available aluminate to sulfate is 0.4 to 2.0. The construction composition exhibits high early strength and sufficient open time.