Determination of exposure classes in the field of wastewater and the resulting concrete cover for reinforced concrete pipes A clarification

摘要

Sometimes, there is an impression of uncertainty among clients and contracting parties about the requirements to impose on concrete and in particular on the concrete cover for reinforced concrete pipes. To be on the safe side, they set excessive requirements which, however, may be detrimental at another point. DIN 4030-1 applies to the exterior of pipes and is relating to the soil and the groundwater. The exposure is classified into XA1 up to XA3. One problem for tendering here is the fact that the former designation "strong attack" used for XA2 now applies to XA3. DWA-M 168 specifies values for the stress inside the pipe and stipulates which stress may occur permanently, temporarily and momentarily. It also has to be considered that discharging a medium with values above the ones proposed according to DWA-M 115-2 may lead to health hazards, apart from a possible attack on the pipe material and/or a reduced effectiveness of the wastewater treatment plant.