| abstract |
Polymers with a high glass transition temperature are used in cement additives to produce a portland cement mortar or concrete that does not have the initial stickiness typical of prior art polymer-modified portland cement compositions and does not form a crust on the surface when exposed to air drying, thus improving the working time of the mix. This simplifies equipment cleaning and permits the use of transit mixers for field applications of polymer-modified concrete. The properties of the mortar and concrete modified with these materials, both in the plastic and hardened state, are equivalent or superior to those of the currently available products which use film-forming materials. Within the scope of this invention are a redispersible powdered cement additive, a redispersible polymer powder and a ready-to-use portland cement composition, as well as related processes. |