The effectiveness of polymer-paraffin emulsions to reduce moisture loss from hardening concrete

The subject of research ishardening concrete with polymer-paraffin emulsions applied to its surface. The effectiveness of polymer-paraffin emulsions deposited on the surface of hardening concrete to reduce moisture loss and reduce shrinkage experimentally investigated.Four types of damp proof membranes in various temperaturesand humidity conditions, as well as in the presence of wind were tested.Moisture losses from the concrete through a protective film of various thicknesses were determined.Tests have shown that the most effective coating was the cationic emulsion EMCORIL B VM. It retained up to 75-90% moisture from the amount lost by unprotected concrete for 72 hours at a temperature of 40 °Cand relative humidity of 30% with a wind speedof 3 m/s.Cationic emulsions are more effective than anionic ones, and polymer-paraffin formulations are more effective than paraffin ones. The rate of evaporation through coatings, regardless of their type and thickness, becomes the same as the rate of evaporation from the open surface of the concrete after the first day of concrete hardening. Therefore, coatings slow down the evaporation of moisture only in the initial period. After that, the evaporation rate is limited by diffusion in the concrete. Studies showed that wind increased moisture loss, but contributed to the rapid drying of the film and a decrease in its vapor permeability in the first hours after applying the emulsion, while a solid film has not yet been formed. Therefore, an increase in wind speed leads to an overall reduction in moisture loss from concrete.