Cured in place pipe (CIPP) enables no dig, rehabilitation and repair of wastewater and drinking water pipes

Global population increase and damaged water infrastructures have led to an increased demand in water infrastructure repair technologies (WIRT). One of the most common technologies is Cured-In-Place-Pipe (CIPP), as it requires significantly less work time, reduces maintenance and is therefore cheaper than other repair methods.

CIPP rehabilitation begins with the impregnation of a liner with a resin, which can be done either at a wet-out facility or directly on the jobsite. The liner is then inserted into the existing pipe, inflated, before being finally cured by water or steam.

The thermoset resin systems that are predominantly applied are unsaturated polyesters and vinylesters, which offer long pot life and fast curing. However, when customers are looking for excellent performance, epoxy is the resin of choice. It exhibits excellent adhesion to substrates, high toughness and offers low shrinkage. Furthermore, an epoxy shows low water absorption and high chemical resistance and does not contain any volatile components. Evonik already offers a broad portfolio of epoxy hardeners that show excellent performance and allow for fast curing. Good examples for that are Ancamide® 2798 and Ancamide® 2781. While Ancamide® 2798 has a gelation time of just two hours at 25 °C and can be cured within two hours using hot water, Ancamide® 2781 is a slower version allowing for a longer processing time of up to eight hours. Nevertheless, due to their medium to high reactivity at room temperature, processing for several days is not possible and therefore epoxy is only used for impregnation on the jobsite so far.