Admixture for producing cementitious compositions having good fluidity and high early compressive strength

A cementitious composition comprising:

• a cementitious mixture comprising:
• Portland cement in an amount from about 60% to about 100% by weight, based on the total cementitious content.
• fly ash in an amount from greater than 0% to about 40% by weight, based on the total cementitious content;
• a water-soluble modified acrylic copolymer superplasticizer in an amount from 0.03% to about 0.4% by weight, based on the total cementitious content;
• an accelerating composition comprising a salt of a thiocyanic acid in an amount from about 0.005% to about 1% by weight, a water-soluble poly(hydroxyalkyl)polyethyleneamine in an amount from about 0.004% to about 0.5% by weight, ethylene oxide adducts of ethylenediamine in an amount from about 0.0001% to about 0.08% by weight;
• and morpholine derivatives in an amount from about 0.0004% to about 0.35% by weight, based on the total cementitious content;
• aggregate in an amount from greater than 0% to about 80% by weight, based on the total cementitious content;
• and
• a sufficient amount of water to effect hydraulic setting of the cementitious composition.

A method for obtaining high early strength and increasing the flow of a cementitious composition, comprising the steps of:

• combining a hydraulic cement;
• an optional SCM;
• a superplasticizer comprising a water-soluble modified acrylic copolymer;
• at least one accelerant selected from the group consisting of salts of thiocyanic acid, water-soluble alkanolamines, ethylene oxide adducts of ethylenediamine, and morpholine derivatives;
• aggregate;
• and a sufficient amount of water to effect hydraulic setting of the cementitious composition.