SEDL / STP / STP1176-EB / STP25547S

Redispersible Polymer Powders for Tough, Flexible Cement Mortars

Schneider, SI
Chemist, Construction Products, National Starch and Chemical Co., Bridgewater, NJ

DeWacker, DR
Senior Project Supervisor, Construction Products, National Starch and Chemical Co., Bridgewater, NJ

Palmer, JG
Market Development Manager, Construction Products, National Starch and Chemical Co., Bridgewater, NJ

Pages: 14    Published: Jan 1993

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Abstract

The increasing use of cement mortars over plywood substrates and in high-rise buildings has demanded new performance requirements of these mortars to overcome dimensional movement in these substrates. A -10°C Tg, glass transition temperature EVA redispersible polymer powder is compared to a +10°C Tg" redispersible, EVA polymer powder for flexural, compressive and tensile strength in a standard three to one sand to cement mortar. Both polymers are also compared for plywood adhesion and flexibility in a standard thin-set formulation. It was found that the -10°C Tg polymer gave increased plywood adhesion at higher levels of modification and superior flexibility while still maintaining comparable strength properties to the +10°C Tg polymer. This would indicate that a -10°C Tg EVA redispersible powder will be better able to bridge gaps in a subfloor as well as allow for subfloor movement due to settling or expansion and contraction due to its better flexibility.