High curing inducing surface applied setting retarder
View Patent ↗Exemplary methods and compositions of the invention for retarding the surface of a hydratable cementitious composition comprise the use of a non-bituminous cationic emulsion comprising at least one curing compound comprising an acrylic polymer, a paraffin, or a mixture thereof, to hinder evaporation of water; at least one set retarder; and at least one cationic surfactant.
1. A method for treating the surface of a hydratable cementitious composition, comprising:
providing a hydratable cementitious composition comprising a hydratable cementitious binder, water mixed with said hydratable cementitious binder in an amount sufficient to initiate hydration thereof, and at least one aggregate comprising sand, crushed gravel, stones, or mixture thereof, said hydratable cementitious composition having at least one external surface; and
spraying onto said at least one external surface of said hydratable cementitious composition surface a liquid coating composition which is a cationic emulsion having an aqueous carrier with substantially no bituminous content, said cationic emulsion comprising:
(a) at least one curing compound comprising a paraffin wax dispersed within said cationic emulsion in an amount of 30%-70% based on total weight of said liquid coating composition and operative thereby to hinder evaporation of water from said external surface of the hydratable cementitious composition after said liquid coating composition is sprayed onto said surface;
(b) at least one component for retarding setting of said hydratable cementitious binder after said liquid coating composition comprising said paraffin wax dispersed within said cationic emulsion is sprayed onto said surface; and
(c) at least one cationic surfactant for dispersing said paraffin wax within said cationic emulsion of said liquid coating composition, said at least one cationic surfactant comprising a salt of a primary, secondary, and tertiary amine; a salt of a di-amine, tri-amine, or poly-amine; or a mixture thereof.
2. The method of claim 1 wherein said at least one cationic surfactant comprises a salt of a primary, secondary, and tertiary amine.
3. The method of claim 1 wherein said at least one component for retarding setting of said hydratable cementitious binder after said coating composition has been applied onto said surface is present in said coating composition in an amount of 1%-20% by total weight of said coating composition.
4. The method of claim 3 wherein said at least one component for retarding setting of said hydratable cementitious binder after said coating composition has been applied onto said surface comprises a carboxylic acid or its salt, malic acid or its salt, tartaric acid or its salt, citric acid or its salt, gluconic acid or its salt, heptagluconic acid or its salt, or a mixture thereof.
5. The method of claim 4 wherein said at least one component for retarding setting of said hydratable cementitious binder after said coating composition has been applied onto said surface is a citric acid or its salt.