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GeneralBrick  PavingPremix AsphaltCast in Place Concrete

Cast-In-Place Concrete


Cast-in-place concrete as a permanent wearing surface over a waterproofing membrane presents a number of potential difficulties. Special care and precautions are to be taken. Derbigum recommends that this method of providing a wearing surface be considered a last resort, and then only in close consultation with Derbigum.

Some of the difficulties to be considered are:

When it is necessary to use this system, the concrete is to be laid on a protective sand/cement screed (approx. 1:6 or 1:8) which in turn is laid on an isolating double layer of 250 micron polyethylene sheeting. Concrete paving is to be cast in panels (generally not exceeding 10m²) creating movement joints which are to be filled with a jointing compound. The size of the joints is to be determined by the Engineer.

Abutments and Edges

The waterproofing membrane is to be turned up at edges to a level higher than the finished concrete level. A soft-joint is to be formed at all abutments so as to accommodate movement in the mass concrete and avoid damage to the waterproofing membrane.


One layer Derbigum CG4 on one layer Derbigum CG3 waterproofing membrane with 75mm side laps and 100mm end laps, sealed to primed surfaces by “torch-fusion”, followed by a layer of 250 micron plastic sheeting with 50mm laps loose laid on waterproofing as isolation/protection layer followed by a 40 mm thick protective screed (by others) to receive cast-in-place concrete (elsewhere specified). Waterproofing to be installed by an Approved Derbigum Contractor.

cast in place concrete parking deck

 Flood Test

The integrity of the waterproofing should be established by means of a flood-test of 48hrs – 72hrs duration, prior to handing over to the contractor. A certificate is to be obtained from the professional team recording the date and time-period of the test and that the waterproof treatment was handed over in a clean, proper and watertight condition.

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