Characterization of the monolayers prepared from emulsions and its effect on retardation of water evaporation on the plastic concrete surface

This paper is concerned about the possibility to prepare compact monolayers from octadecanol (OA) emulsion on the plastic concrete surface in order to restrain water evaporation. The concrete was prepared with ordinary Portland cement with typical water to cement ratio = 0.5. The results showed that the monolayers prepared from the emulsion could effectively reduce the water evaporation on the concrete surface, especially for the emulsion containing 0.12 g sodium dodecyl sulfate (SDS) and 0.48 g sorbitan monododecanoate (Span20) which could reduce the water evaporation to 41%. The microstructure of the monolayers was characterized by surface pressure–area (π–A) isotherms, dynamic elasticity (π–Ed) curves and atomic force microscopy (AFM). It is revealed that the emulsifier concentration has great influence on the monolayer structure. High emulsifier concentration would lead to the monolayers with incompact, unstable structure and low water evaporation resistance due to the good solubility of the emulsifier.