The first waterstops used in construction were comprised of strips of lead or copper. In the early 1900s the preferred waterstop material shifted to vulcanized rubbers such as neoprene or styrene butadiene rubber (SBR). While rubber waterstops had excellent mechanical properties (high tensile strength and great elongation) they had one major weakness: they were extremely difficult to field fabricate as the rubber was vulcanized, meaning it had already taken a “set” (thermoset) and could not be heat welded together like the metals used previously.
In 1926, a new plastic compound was invented by Waldo Semon of the B. F. Goodrich Company: plasticized PVC. Semon was attempting to dehydrohalogenate (non-plasticized) PVC in a solution of boiling solvent in order to to create an unsaturated polymer that would be useful for bonding rubber to metal. The results of Semon’s experiment was the creation of a thermoplastic with properties very similar to rubber. It took many years for plasticized PVC to find suitable commercial applications, and was first used as a waterstop material in the early 1950s. Back then, the material was properlylabeled as fPVC or flexible PVC.
The first wide-scale test of any waterstop was performed in 1954 by the Hydro-Electric Power Commission of Ontario, Canada. The results of this test are still used by many manufacturers as a benchmark, and other than some new polymers, waterstop has not really changed that much since then.
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