Evaluation of peel resistance of paint coatings depending on the roughness of the cement substrate

Abstract

The object of the study is paint and varnish coatings of cement concrete. The goal is to evaluate the stress-strain state of coatings under the action of temperature depending on the geometry of the substrate roughness relief. The results of calculating the distribution of stresses over the cross section of the coatings and the possibility of their peeling are presented. The SCAD Office software module was used for the calculation. Heavy concrete was considered as the substrate. Polyvinyl acetate cement PVAC paint was used as a paint composition. The calculations were carried out for the conditions of Moscow. A comparison is made of the stresses in the coating on a smooth and rough surface. I has been found that an increase in the relief angle of the substrate surface roughness does not cause a significant change in the magnitude of stresses. The stress concentration in the zone of contact between the coating and the rough surface of the cement substrate has been established. A diagram of the distribution of stresses in the PVAC coating is presented. It was revealed that at some distance from the zone of the microdepression of the substrate surface relief, an increase in stresses is observed, which, depending on the angle of inclination of the relief, are s х = (1.007-1.021) MPa. At the peak of the relief, the stress values in the contact zone are less and amount to 0.403-0.441 MPa. The influence of the substrate roughness has practically no effect on the values of normal stresses on the coating surface, which are 0.835-1.001 MPa. The probability of peeling off the coating is estimated. The possibility of peeling of the coating has been established, tk. stress values are less than the adhesion strength, which is 0.9-1.1 MPa. It is recommended that in order to increase the resistance of coatings to peeling, strive to create a uniformly distributed roughness of the substrate surface.