Abstract: A hydraulic cement mix including hydraulic cement, aggregate, sufficient water to effect hydraulic setting of the cement, and an additive comprising a mixture of an alkali or alkaline earth or ammonium salt of thiocyanic acid, such as sodium, potassium, lithium, calcium or magnesium thiocyanate, and an alkanolamine, such as triethanolamine, the additive being present in an amount sufficient to increase rate of hardening, and the compressive strength of the hardened mix. Generally, the additive is present in a total amount of up to about 2.5% by weight based upon the weight of the cement, usually in an amount of between about 0.05% and about 2.55% by weight based upon the weight of the cement, preferably in an amount in the range of about 0.4% to about 0.6% by weight.

Abstract: A method is provided for improving the strength and other properties of non-plastic dry hydraulic cement mixes, such as the dry concrete mixes used for making concrete masonry units. The method comprises incorporating a synergistic combination of two additives into the cement mix. The first additive is a salified methyl or ethyl substituted benzene or naphthalene sulfonate, and is preferably added in an amount of between about 0.01 and 1%, by weight based upon the weight of the cement. The second additive is a tertiary aliphatic amine oxide, and is preferably added in an amount of between 0.001 and 0.1%.