Friday, February 13, 2009

Concrete and Plastic Adhesive

Concrete
Bisphenol A epoxy resins stick well to dust free old concrete, but more interesting is their use to bond new concrete to old. The method is simple; the old concrete is coated with adhesive containing an amine hardener, and while the resin is still uncured the wet concrete mix is placed on top. For best adhesion, it is common practice to include a proportion of rather large material as aggregate in the new concrete.

The use of epoxy adhesives in the repair of concrete roads and in other applications concerned with roadways is growing in importance. The subject of adhesion to concrete has been comprehensively studied by Johnson, and with special to epoxy resin.

Plastics
With the exception of the fluorocarbon polymer which require special surface treatment, the organic plastics, especially thermosetting ones, can in most cases be glued satisfactory, but in order to obtain the best result it is advisable to experiment with different hardeners, fillers and flexibilisers. A large addition of versamid increases adhesion to nylon and polyvinyl chloride, and in bonding to plastics generally, without regard for heat resistance, a Versamid-cured system provides a near universal adhesive. Excellent adhesive strength has been reported by the Picatanny Arsenal, on such strong thermoplastic polymers as polycarbonate (Lexan) and polyacetal.

Bonding to polyester glasscloth laminates in an application of increasing importance and excellent strength have been reported for a system in which the use of a Versamid hardener, although unnamed, may be inferred.

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