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On the A24 Blankenburg connection, construction consortium BAAK, commissioned by the Department of Public Works, is hard at work on the Holland Tunnel and the access ramps to the Maas Delta Tunnel at a depth of 33 meters. Due to supply problems with the initial applicator, the consortium had to find an alternative at lightning speed. The solution was found at Special Industrial Repair (SIR) and in particular at sister company Polyproof.
"For waterproofing approximately 7,000 m2 to tunnel deck, we had initially approached about three applicators," says Michael Dekker, project coordinator at BAAK. "The work was awarded to a party that ultimately could not deliver at the very last minute. This applicator's supplier could not deliver. In order not to disrupt the schedule, we had to urgently look for an alternative. Through Adcos, supplier of waterproof coatings, we came into contact with SIR and eventually Polyproof. SIR was already known to BAAK as a subcontractor for making waterproof injections. Polyproof then followed through very quickly and decisively. The end product is considerably more expensive, but of higher quality."
Polyproof recently achieved a feat of Olympic proportions on the Blankenburg connection, according to case manager Hans Bos. "Two weeks before a gigantic sand package was to be applied to the ramp to the immersion tunnel, we were asked to waterproof the tunnel deck with the product Polyurea. It is a hot spray coating, applied from a specially equipped mobile unit, in an almost artful but highly professional manner. For the progress of the project, it was important to pick it up quickly. Given the not insignificant size of 1,700 m2 and the familiar ups and downs with delivery times because raw materials are hard to come by, quite a challenge. At these moments you notice how important it is to have a network of real partners. Our supplier Adcos has supported us enormously by changing the planning and producing exclusively for us. It enables us to move quickly."
On Thursday, Polyproof received the order, exactly one week later a team of professionals was already on the tunnel deck. "Even in that interim period, an awful lot of work was done," says Rens Olij, technical calculator and responsible for work preparation and quality assurance on the project. "We tackled the preparation very quickly and adequately including drawing up a work plan, work instructions and an RI&E in consultation with BAAK. Once on site, the tunnel deck was first cleaned with high pressure and then dried by BAAK. Primer coats were then applied that same day. Then, in one coat, the Polyurea was sprayed on at 70 degrees Celsius from our multi-component reactor metering pump."
Polyurea is formed by two components. Thanks to its exceptional chemical properties, the product is highly reactive, making it an ultimate fast-curing spray with excellent adhesion to metal, concrete and foam. The waterproof layer is walkable after 13 seconds and after 24 hours you can drive over it with large equipment. The result is an uninterrupted, waterproof coating, with no harmful effects on the environment. "Immediately after application, we check the layer for adhesion, homogeneity and any unevenness. Critical points are marked and immediately touched up. After all, we only go for a 10. All our findings are recorded visually and compiled in daily reports, including parameters such as weather conditions, and the final result is also checked by our supplier Adcos."
In the end, Polyproof's professionals completed the waterproofing of the first 1,700 m2 to tunnel deck in just four days. "You just can't see any of it anymore, unfortunately," says Bos. "Just one day later, BAAK started backfilling the soil package, an embankment of some 14 meters on the tunnel deck." He is therefore particularly proud of the ad hoc performance. "Thanks also to the support from BAAK itself. Such an Olympic achievement can only be achieved together." Bos is convinced that Polyurea can be used much more widely in infra and hints at sealing parking decks, bridge decks, tunnels, bridge piers, canal corridors, bicycle parking, etc., among other things. The product is also root resistant for the purpose of green roofs, solvent-free, resistant to oils, greases and chemicals, making it an extremely sustainable application as well."
