Flexible binders, their degradation and impact on cement substrate

Compared to the traditional inorganic binders based on mortar or plaster, cementing clefts and cracks with polymer fl exible binders is effective in terms of better adhesion and fl exibility. Nevertheless, in order to be applicable in restoration practice they must comply with the condition of a minimum impact on the substrate, which frequently is a porous material. Silicon-based binders, synthetic rubber and hybrid binders based on silicone modifi ed with polyurethane and polyether were tested in this study. The binders were artifi cially aged under various conditions. At the same time, the study also focused on the extent of infl uencing of the porous cement substrate by the application of binders. The silicone binders showed the best resistance to artifi cial aging, however, the originally hydrophilic substrate became hydrophobic. Hybrid binders showed better resistance to moist rather than dry atmosphere. Testing in the QUV panel caused cracking and incoherence of all hybrid bonders. Various categories of binders showed similar properties in terms of resistance to aging and the extent of infl uencing of the porous substrate. The porous cement substrate was reported to be substantially infl uenced by all tested binders. Therefore, none of the tested binders can be unambiguously recommended for application in restoration practice.