BRIDGE DECK WATERPROOFING
Generally the bridge deck waterproofing system is based on the PUMA technology.We talk about a liquid and cold applied membrane system which is applied as waterproofing under the asphalt on the bridge deck. If we look to the bridge deck waterproofing market in total we must say that at least 85% of the bridge deck waterproofing systems used on concrete bridges under asphalt are bitumen based. In most of the cases also a bitumen based primer is used.
In some European countries an epoxy based primer is used instead of bitumen based primer. The advantage of epoxy based primers over bitumen based primers is of course the better adhesion to the concrete based bridge deck.
The system is very simple: After the substrate preparation (shot blasting or water jets) of the concrete bridge deck, a first layer of 0,5kg/m² epoxy primer with a consumption rate of 0,5kg/m² is applied. This layer is broadcasted with 1kg/m² natural quartz (ca. Ø 0,7 – 1,2 mm). The next day a second layer of epoxy primer with a consumption rate of 0,6kg/m² is applied onto the previous layer. After the second layer is applied we have to wait again min. 12 hours before they can start with the application of the bituminous felt onto the primed surface. A very important point is that during the application of the epoxy primer is that the ambient, substrate and material temperature must be not less than 15°C. Also after each application step of the epoxy primer the area has to be protected for at least 24 hours against rain. If during the first 24hours water comes onto the primed area the result can be that the primer stays tacky which will have a negative impact to the adhesion of the bituminous felt later. This means that the weather conditions can provoke rather big delays of the waterproofing works on a bridge deck.
This was one of the reasons why the applicators using epoxy primers under bitumen based waterproofing systems on bridges, have asked to develop a primer based on MMA which can be used under bitumen based waterproofing systems on bridges.
This is a low viscous 2 component reactive resin based on methyl methacrylate (MMA). The product is intended for use as a primer/sealer under asphalt or bitumen waterproofing. It has excellent bond to concrete and metal substrates and also provides a good bond for following waterproofing systems.
The complete primer/sealer system consists of two coats.
The first coat is applied by squeegee and back rolled at a rate of 0,5kg/m² and while still fresh broadcast with natural quartz size 0,7 – 1,2mm at approx. 1 kg/m². A second layer is than applied by roller at a rate of 0,4 – 0,6 kg/m² and allowed to cure. Please find some photos taken during the application of the system.
Application of the first layer of MMA Primer including broadcasting:
Area after application of the second layer of MMA Primer: Application of the bituminous felt onto the primed bridge deck:
Application of the bituminous felt onto the primed bridge deck: Control of the adhesion of the bituminous felt:
The key benefit summary of the product can be seen as follow:
- Excellent adhesion to concrete and metal
- Fast curing even at low temperatures down to -5°C
- Can be used under critical weather conditions
- First and second layer of the primer/sealer system can be applied during the same day
- Bituminous felt can be torched on to the primed surface latest 90 minutes after the second layer was applied
- Time and cost reducing because the total system, primer and bituminous felt, can be applied in one day