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Solvent-Free sealant creates smooth concrete surface for coating


Exterminating the problem of concrete bugholes

One of the galling glitches of hardened concrete structures is the “bughole,” a small hollow caused by a bubble of air trapped against the side of the support form as the concrete hardens, leaving a permanent void in the finished surface. Bugholes pose a significant problem when applying high-performance coatings to concrete surfaces, and need to be filled in order to achieve a smooth finished coating. Desmoseal® S XP 2636 silane-terminated polyurethane prepolymer by Bayer MaterialScience is used as a base resin in a solvent-free, one component sealant ideal for eliminating bugholes in concrete surfaces.

To eliminate bugholes before a high-performance coating is applied to a concrete substrate, a simple caulking gun is used to inject a formulated product based on a Desmoseal® resin into a void. The uncured product is then pulled flush with a putty knife, creating a smooth surface ready for coating. This process eliminates the risk of bughole-induced outgassing through the post-applied coating. Outgassing occurs when air becomes entrapped within the cavities and expands over time from the heat of an exothermic coating, thereby causing pinholes, blisters or other defects in the finished surface.

Desmoseal® S XP 2636, a silane-terminated prepolymer, is part of a new class of materials that cure with moisture from the air, or from the substrate to which they are applied. The finished products will not foam in the presence of water, and have excellent UV stability and good adhesion to concrete. The products also have very fast re-coat time and can be formulated without solvents.


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