Evaluation of the contact angle and frost resistance of hydrophobised heat-insulating mortars with polystyrene

Abstract

The aim of the research presented in the paper was to evaluate the feasibility of using hydrophobic preparation based on organosilicon compounds for surface protection on the heat-insulating mortars modified with polystyrene. The work discusses issues related to wettability, absorptivity and frost resistance of the surface layer of mortars. The experimental part pertains to the physical and mechanical properties of polystyrene-modified mortars and the influence of hydrophobic preparation on the contact angle and frost resistance. The frost resistance of mortars was examined following 25 cycles of freezing and thawing. The contact angle of light mortars (θw) was determined before and after the tests of frost resistance, in the function of time using a single measurement liquid. This provided a basis for calculating the surface free energy with Neumann method, characterizing the wettability and adhesion of mortars under normal conditions and with damages resulting from frost weathering. The structure of mortars and the adhesion of lightweight aggregate to cement paste were presented by means of scanning electron microscopy. The studies enabled to determine the hydrophobisation efficiency of heat-insulating mortars with polystyrene. The obtained results confirmed the possibility of producing heat-insulating mortars modified with polystyrene along with proper surface protection against moisture and frost.