Waterstop 101: Guidance for Proper Waterstop Installation

Waterstop is commonly required to provide a watertight seal at construction joints in concrete structures and is an important feature of new and remedial dam construction projects. Steps taken to ensure high quality waterstop installation are critical to the safe operation and long term viability of a dam project. Yet training on proper waterstop installation is extremely difficult to obtain. One is hard pressed to find even a mention of waterstop in civil engineering curriculum. As a result of this lack of direction, poor quality waterstop installation frequently occurs at dam construction sites and it is the inspecting engineer's responsibility to identify the problems and demand corrective action. The author will present information gleaned from construction inspectors with years of concrete construction experience. Power Point presentation slides of both poor quality and appropriate waterstop installations observed at dam construction projects in Pennsylvania will be reviewed. The slides will address proper alignment and even embedment of waterstop material, concrete formwork adaptations and methods of stabilizing the material to withstand stresses of concrete placement. Special attention will focus on the fabrication of joints in the field with details on efficient sequence of cuts, proper joint welding and the advantages of pre-fabricating the more complex joints. During the final 10 minutes of the presentation, the author will demonstrate the ease in making a clean, even waterstop butt joint using the proper tools: an electric iron and a plywood jig. The welded joint will be passed around for hands-on proof that a properly fabricated joint is just as strong as the waterstop material. 4 pp., 11 figures, 2 references.