In the construction industry, buildings typically have floors made of concrete. Concrete floors are manufactured from liquid cement mixtures that are poured into molds or forms that frame floors. The cement mixtures cure and harden forming concrete floors. The cured concrete floors must be substantially straight and level prior to applying finish flooring such as tile or carpeting.
The cement mixtures usually comprise cement, sand, and water. The cement mixtures are viscous such that laborers must use trowelling tools to smooth the surfaces of the mixtures once they have been poured. Trowelling tools create rippled surfaces which require additional manual labor for smoothing. The cured concrete floor is typically uneven.
In an effort to reduce the cost of labor and difficulty of leveling poured cement, cementitious materials having a self-leveling or self-smoothing agent are typically applied over uneven concrete floor substrates in a thin coating. Since these thin coatings are self-leveling, they must nevertheless be applied sufficiently thick to fill the depressions in the surface of the uneven concrete floors so that the final, level surface is composed solely of the coatings for uniformity of appearance and texture. These coatings are typically made from cement mixtures which contain casein as the self-leveling agent. Casein is a natural product formed by the precipitation of milk by an acid. On the average it is composed of 95% proteins, 1% fats, 12% water and 3% ash. Casein is a powdered material that is typically added to the cement mixtures while dry. Upon the addition of water and sodium carbonate the cement mixtures becomes self-leveling.
Casein, however, as a self-leveling additive has many drawbacks. It is difficult to use since it does not dissolve easily in water. Sodium carbonate, which facilitates the mixing of casein with water, must be added to the mixtures at the construction site. The aqueous cement mixtures must then set for 10 to 15 minutes prior to application. The presence of the sodium carbonate itself creates problems in that it often causes small holes and craters to appear on top of the level surfaces. Since the concrete floor surfaces must be level and smooth prior to applying any floor coverings, the holes and craters must be sanded away. More labor costs result.
The quality of casein is also inconsistent. As a by-product of milk, its composition varies making quality control difficult to manage. Composition can be affected by the quality of grass consumed by cows, the location in which the cows are raised, and the season of production.
Thus, there exists a need for a self-leveling coating material for floors that alleviates problems associated with those coatings containing casein and yet produces a smooth, level floor surface to facilitate the effective application of floor coverings. Accordingly, it is to the provision of such an improved self-leveling material that the present invention is primarily directed.