Impact of Freeze-thaw Cycles on Coatings Applied to the Surface of Alkali-activated Materials

Abstract

This paper focuses on the possibility of applying selected types of coatings (synthetic and epoxy) on the surface of alkali-activated
materials based on finely ground granulated blast furnace slag with an admixture of cement by-pass dust and silica fly ash.
Admixtures represent 30% of the binder component (15% fly ash, 15% cement by-pass dust). The mixture is activated with
anhydrous disodium metasilicate. The samples were categorized into two series samples stored in water and samples wrapped in
foil. Following this, the surface of these two series was modified by two methods, namely brushing with a steel brush and
roughening with a diamond wheel. The properties related to the adhesion of the coating to the surface were mainly investigated
before and after 100 freeze-thaw cycles. The cross-cut method and pull-off test for adhesion determined the adhesion. The crosscut
test found that the synthetic coating was less susceptible to surface modification than the epoxy coating. The samples were
exposed to 100 freeze-thaw cycles. Then, the cross-cut method was applied to the coated roughened surface and the results of this
test were classified into category 3. During the determination of the adhesion of the coatings by the pull-off test on the roughened
surface for both methods of sample storage, the character of breakage for the synthetic coating was of the cohesive type, thus it
was the tensile strength of the materials, while for the epoxy coating, it was the adhesive breakage, thus it was the adhesion
between the surface and the coating.