Additive composition for strength enhancement of cementitious compositions

A method of enhancing the strength of a cement composition, the method comprising the steps of:

• (i) grinding a solid comprising Portland cement clinker in the presence of an additive thereby preparing the cement composition, or
• (ii) making concrete from a mixture of a solid comprising Portland cement, sand, coarse aggregate, water, and an additive,
• wherein the additive comprises:
• an alkanolamine comprising ethanoldiisopropanolamine (EDIPA) and optionally at least one selected from the group consisting of triisopropanolamine (TIPA), diethanolisopropanolamine (DEIPA), triethanolamine (TEA), and tetrakis-(2-hydroxyethyl)ethylenediamine (THEED);
• at least one set retarder selected from the group consisting of a gluconate salt, sucrose, corn syrup, and molasses;
• and
• at least one set accelerator selected from the group consisting of a thiocyanate salt, sodium chloride, and calcium chloride,
• wherein the alkanolamine and the set accelerator are present at a mass ratio of from 0.2 to 4.0 and the set accelerator and the set retarder are present at a mass ratio of from 1 to 10, and wherein the cement composition, when cured, has a compressive strength at 2 days and at 28 days that is at least 10% higher than a cement composition without the additive.