Cement-reduced construction composition

A cement-reduced construction composition comprising

• a) a cementitious binder comprising one or more calcium silicate mineral phases and one or more calcium aluminate mineral phases, and having a Blaine surface area of at least 3800 cm2/g, in an amount of 180 to 400 kg per m3 of a freshly mixed construction composition;
• b) a fine material having a Dv90 of less than 200 μm, selected from alkali-activatable binders, rock powders and inorganic pigments, or mixtures thereof, in a total amount of 20 to 200 parts by weight, relative to 100 parts by weight of cementitious binder a);
• c) optionally, an extraneous aluminate source;
• d) a sulfate source;
• and
• e) a polyol in an amount of 0.3 to 2.5 wt.-%, relative to the amount of cementitious binder a);
• wherein the composition contains available aluminate, calculated as Al(OH)4−, from the calcium aluminate mineral phases plus the optional extraneous aluminate source, per 100 g of cementitious binder a), in a total amount of
• at least 0.08 mol, if the amount of cementitious binder a) is in the range of 180 to less than 220 kg per m3 of the freshly mixed construction composition,
• at least 0.06 mol, if the amount of cementitious binder a) is in the range of 220 to less than 280 kg per m3 of the freshly mixed construction composition, and
• at least 0.05 mol, if the amount of cementitious binder a) is 280 kg or more per m3 of the freshly mixed construction composition;
• and the molar ratio of total available aluminate to sulfate is 0.4 to 2.0;
• the construction composition further comprising
• f) an ettringite formation controller comprising (i) glyoxylic acid, a glyoxylic acid salt and/or a glyoxylic acid derivative;
• and (ii) at least one of (ii-a) a borate source and (ii-b) a carbonate source, wherein the carbonate source is selected from inorganic carbonates having an aqueous solubility of 0.1 g·L−1 or more at 25° C., organic carbonates, and mixtures thereof, and
• g) a co-retarder selected from (g-1) α-hydroxy monocarboxylic acids and salts thereof, (g-2) phosphonic acids and salts thereof, (g-3) polycarboxylic acids and salts thereof, and mixtures thereof.