Hy-Rib is also used to form the construction joints in water retaining structures. It can be used either with or without waterstops. As with all construction joints, good workmanship and supervision are essential. The Hy-Rib will be given the same cover as the reinforcement, and can therefore be used on water structures, such as treatment plants, tanks etc. The application of Hy-Rib in water retaining structures is no different to that for other structures.

Hy-Rib can also be used with hydrophilic and bentonite type water stops. It is recommended that wherever the waterstop is to be positioned, a timber or plastic strip corresponding to the width of the product is fixed between adjacent sheets of Hy-Rib prior to the first concrete pour. See Figure 1(a). After the first pour, remove the timber or plastic strip and fix the waterstop to the flat surface as per the manufacturers instructions, indicated at Figure 1(b).

It was previously thought that the open meshed structure of Hy-Rib would cause concern at central type waterstops. Research in November 1993 at Imperial College confirmed that the open nature significantly reduced the trapping of air and risk of honeycombing under the flat section of the waterstop. The report states “compaction of concrete immediately beneath the waterstop is better using Hy-Rib compared to a solid face such as provided by plywood”.

The code “Design of concrete structures for retaining aqueous liquids”, BS 8007, accepts that it is not necessary to incorporate waterstops in properly constructed construction joints.