Experimental Investigation of Adhesion Failure between Waterproof Coatings and Terrace Tiles under Usage Loads

Barbara Francke,Artur Piekarczuk

doi:10.3390/buildings10030059

Abstract

This paper analyses the mechanism of the loss of functional properties of water-impermeable products used under ceramic tiles bonded with adhesives. Recorded damages were caused by selected ageing factors and were measured by the loss of adhesion of individual layers of the set. The analyzed phenomenon is found mainly on terraces and balconies located in a mid-European transitional climate, i.e., exposed to temperatures passing through 0 °C for three seasons a year. The tests reflected the action of three main functional factors, i.e., temperatures, water and freeze/thaw cycles. Tested waterproof coatings were grouped into three types, i.e., dispersion, cementitious and reaction resin-based products. Research kits consisted of liquid-applied water-impermeable products laid on a concrete substrate, adhesives and tiles. Comparing the effects of the action of the above-mentioned ageing factors revealed that water has the greatest impact on the reduction of the tensile adhesion strength of such sets. The adhesion of waterproof coatings to the concrete substrate showed higher values than the adhesion between the waterproof coating and the tile adhesive layers, regardless of the coating material. Both for samples not exposed to ageing factors, and for those exposed to such impacts, failure usually occurred in the adhesive layer or between the tile adhesive and the waterproof coating, without damaging the waterproof layer. The loss of adhesion of finishing layers to the substrate was not accompanied by a loss of tightness of the waterproof coating. The impact of negative water ageing was particularly destructive on the adhesion of cement-based tile adhesives to waterproof coatings made of polymer with a water dispersion of absorbability above 7% (V/V). There was no correlation among the results of adhesion of the finishing layers to the waterproofing layer after the action of the three ageing factors, i.e., water contact, elevated temperature and freeze/thaw cycles.

Highlights

The majority of processes which destroy building materials take place in the presence of water or moisture and that is why structures must be protected from the ingress of unwanted rain water, water accumulated in the soil [1], water splashed on the floor in wet rooms, as well as water which accumulates on the surface of terraces and balconies
In terms of: water contact at (23 ± 2) ◦C, a high temperature of (+70 ± 3) ◦C and freeze/thaw cycles under variable temperatures ranging from (−15 ± 3) ◦ C to (+15 ± 3) ◦ C, of systems intended for use on terraces and balconies, which consist of: concrete substrate, waterproof coating made of liquid-applied water-impermeable products, tile adhesive and ceramic tile, helped to draw the following conclusions:
Comparing the effect of water, elevated temperature and freeze/thaw cycles on terrace sets, in which the waterproofing layer is made of a coating product, and the finishing layer of ceramic tiles is glued with adhesives, it can be stated that water has the greatest impact on the reduction of the tensile adhesion strength to the substrate of liquid-applied products under tiles, the adhesion of waterproof coatings to the concrete substrate shows higher values than the adhesion between the waterproof coating and the tile adhesive layer, regardless of the coating material

Summary

Introduction

The majority of processes which destroy building materials take place in the presence of water or moisture and that is why structures must be protected from the ingress of unwanted rain water, water accumulated in the soil [1], water splashed on the floor in wet rooms, as well as water which accumulates on the surface of terraces and balconies. This article is devoted to assessing the durability of one of the above-mentioned areas of application of waterproofing, i.e., waterproofing layers of terraces and balconies, assuming that the durability of this part of the covering determines the proper protection of the structure against water and moisture This area is exposed to temperature variations along daily or seasonable cycles, inducing expansions and contractions in building materials [2]. The shrinkage and expansion of cementitious materials like tile adhesive mortars, in relation to the presence of water and temperature changes, have been discussed in many scientific articles In those investigations, the tile–mortar interface was found to be a zone, where failures often occur first. Numerous analyses have been carried out in terms of tensile and shear stresses appearing in the structure of the adhesive mortar, depending on its composition, and the effect of tile size and colour on the adhesion of ceramic tiles to the substrate

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