Cement modifiers solid acrylics

Acrylic latices have been used successfully for more than 35 years to modify portland cement composites. The use of solid grade acrylic cement modifiers has become common during the past few years. Both of these types will be discussed later in this section. The level of polymer modification is measured as a ratio of polymer solids by weight of cement. A 15%-20% modification represents the range for optimum performance lower modification levels may prove acceptable for certain product applications (Rohm Haas, 1989). 

In recent years solid grade acrylic cement modifiers have become more popular, for many reasons ... 

Table 5.8 Typical physical properties of acrylic redispersible powers. Source Tsai, M.C., Burch, M.J. and Lavelle, J.A., Solid grade acrylic cement modifiers, in Polymer Modified Hydraulic Cement Mixtures, ASTM STP 1176 (eds L.A. Kuhlam and D.G. Walter), Table 1 published by the American Society for Testing and Materials, Philadelphia, PA, 1993...

Acrylic emulsions (or acrylic latices) are characterised as high-solids polymers having a film-forming temperature at or below room temperature (Lavelle, 1986). They have excellent hydrolysis resistance compared with other resins and are well suited as modifiers for portland cement mortars. Studies have shown that certain acrylic latices impart excellent workability at lower water demand, thin section adhesion and toughness, improved flexural strength and tensile strength and outstanding adhesion (Lavelle, 1983). 

In addition to the use of dry acrylic powders in cement mortars, other typical uses for these modifiers are in cement toppings, ceramic tile adhesives, ceramic tile grouts, white masonry paints and cement block fillers. It is obvious that these compounds are more convenient to use with the simple addition of water, than those compounds requiring the addition of a latex emulsion. As improvements are made in these dry powders, there will be more emphasis on this type of compound. At the present time, the dry powder acrylics are more costly than the latex emulsions on a dry solids basis. 

---