Abstract: A method of producing cementitious mixtures containing fly ash as one of the cementitious components, under air entrainment conditions is described. The method involves forming a mixture comprising water, cement, fly ash, optionally other cementitious materials, aggregate, conventional chemical admixtures, and an air entrainment agent and agitating the mixture to entrain air therein. Additionally, at least one amine sacrificial agent is included in the mixture. The cementitious mixtures and hardened concretes resulting from the method and fly ash treated with sacrificial agent, or air entrainment agent/sacrificial agent combinations, are also described.

Abstract: The invention relates to copolymers effective as slump retention agents for hydraulic compositions such as cement, mortar and concrete. The copolymers are formed by reacting monomers A, B and C, wherein monomer A is a compound of formula I, monomer B is a compound of formula II, and monomer C is a compound of formula III or IV as shown herein. The copolymers may be used alone or in combination with a water reducing agent or slump retaining agent, e.g. a superplasticizer such as PNS or PMS or a low range water reducer such as lignosulfonate. The copolymer includes a group that is hydrolyzable at elevated pH (e.g. around pH 12) typically present in hydraulic compositions, so that the group hydrolyzes when present in such compositions and forms a charged group that provides extended slump retention properties without introducing undesirable air-entraining characteristics.