marginally significantp < 0.045
A statistically significant difference was presented by the samples without waterproofing resin ( F (1, 45) = 31,386, p < 0.032; R 2 = 0.411), marginally significant for the samples with the application of a layer of waterproofing resin (single layer) ( F (1, 45) = 22,618, p < 0.045; R 2 = 0.682) and not significant for double layer ( F (1, 47) = 23,853, R 2 = 0.752, p < 0.065).