Waterstops

Claim 1

A waterstop of the type used to provide a water seal at a face of a concrete joint formed by two adjacent and separately poured masses of concrete, said waterstop comprising a strip of moisture or water-resistant flexible material, said strip having a longitudinally extending center line and at least one keying formation projecting laterally from said strip on each side of the center line thereof, said keying formations all projecting from the same face of said strip and running longitudinally along the length thereof, said keying formations being structured such that the formations broaden out from the point at which they project from said strip, said strip further having substantially at said center line an easily deformable section of about 1-2 inches in width comprising a plurality of upstanding ribs formed of moisture and water-resistant flexible material, each of said ribs is of a rectangular cross-section, about 1/32 to 1/4 inch thick and about 1/4 to 3/4 inch high, and separated from each other by a distance of 1/16 to 3/8 inch and running longitudinally along the length of said strip and projecting laterally from the same surface as said keying formations, each of said ribs further being of sufficient deformability that the rib will easily fold over and conform to the configuration of stop-end shuttering placed thereon during the formation of said separately poured masses of concrete.