Performance of waterstops at different temperatures

Waterstops are installed in the body of concrete (to a depth of 30-60 cm) during the construction of hydrau- lic structures to minimize or eliminate all possible leaks at construction joints. However, they often deteriorate as a re- sult of the thermal variations and hydrostatic pressure to which hydraulic structures are subjected over their lifetime. Since repairing or replacing deteriorated waterstops is very complicated and costly, they are normally left in place and new ones installed close by. Various new products and methods have now been developed for this purpose, but their performance is not well documented. Eighteen different products were initially chosen and subjected to a battery of laboratory tests (viscosity, chemical compatibility with water, and freeze-thaw cycling) at 23 °C, 15 °C, and 5 °C. Four of the 18 products were subsequently tested for permeability and apparent adherence in a specially designed setup. The test data showed that the waterstop that best fulfilled the criteria was a two-component polyurethane resin.