Pre-applied fresh concrete bonding system - mechanically fully bonded sheet membrane DualProof

Pre-applied Waterproofing: Understanding concrete bonding methods

Pre-applied waterproofing is used to seal below grade concrete basement slabs and to waterproof concrete walls on the waterside as a fully bonding membrane / blindside waterproofing on job sites where there is limited space for excavation and heavy equipment. Instead of pouring the foundation and then applying waterproofing to the outside of the concrete wall, a pre-applied waterproofing membrane is placed on the formwork or as a blindside membrane before the concrete is poured. The slab and wall concrete are then cast into the pre-applied waterproofing membrane.

A fully-bonded, pre-applied fresh concrete bonding membrane (also used as a blindside membrane) must seal tightly to the concrete to prevent lateral water migration between the membrane and the structural concrete in case of punctual damage.

It must be able to stay in place, even if the concrete (slab / wall) cracks or the soil beneath begins to settle. The fully mechanical bonding effect must work during the expected lifetime of the basement / foundation to avoid leaks during the entire lifetime of the building.

The fully bonded membrane must be open for vapor transmission to avoid delamination and blisters, but must be permanently waterproof against groundwater.

Conclusion

Pre-applied waterproofing membrane are available in different materials. HDPE, TOP/FPO and PVC. BPA has clearly decided not to use a HDPE passed pre-applied system, because the SD-value of 900 up to 1000 m is too high and does not allow moisture and vapor transmission through the membrane, which causes blisters and delamination. The pressure sensitive adhesion layer is not permanently resistant and stable for high alkaline moisture and vapor, and it therefore not full functional during the structure lifetime. TPO/FPO and PVC based membranes are watertight but open for moisture and vapor transmission through the membrane. The special Barritex fleece we have tested is high alkaline resistant and durable for the lifetime of the basement / concrete structure. The mechanical bonding layer (fleece) has a positive side effect and improves the concrete edge and avoids voids, bugholes and internal pores.

BPA has two pre-applied fresh concrete bonding systems in their product range, a PVC based one and a TPO/FPO based one. Both membranes are laminated with a special Barritex fleece without using a bonding agent. The mechanical bond is excellent and durable and can withstand lateral waterflow up to 11 bar which is equal to 110 meter water column.