Quantitative distribution patterns of additives in self-leveling flooring compounds (underlayments) as function of application, formulation and climatic conditions

The distributions of organic additives in self-leveling flooring compounds (SLCs) were investigated using laser-scanning microscopy for the selective visualization of the additives, which had been previously stained by a fluorescent dye. The distributions of latex (VC), polycarboxylate ether (PCE), cellulose ether (CE), casein (Cas) and polyvinyl alcohol (PVA, a component of redispersible powders) were analyzed in Portland (PC) and Calcium aluminate cement (CAC) dominated SLC formulations as a function of application thickness and different climatic conditions. It is shown that evaporation induced water flux through the communicating pore system causes considerable enrichments of these additives in the uppermost millimeter of the mortar layer. The resulting fractionation factors can be correlated with the different hydration kinetics of PC or CAC dominated mixed binders as well as with the drying conditions. Investigations on the additive distribution indicate that CAC dominated formulations develop more homogeneous enrichments than PC dominated systems.