Watertightness of New Lock guaranteed thanks to special membrane system

"Given the complexity of the project, extra care had to be taken with the waterproofing of the New Lock. Since BAM and Sika have worked together in this area before, we were invited to the table to help think about the right solution," Cousin opens the conversation.

That solution was found in applying a compartmentalized membrane system (foil), a specialty of the Sika Group. Eroll Breukers, construction sales manager at Sika explains: "Of course the lock is designed safely. A huge amount of reinforcement is already used in the concrete, but because the concrete is subject to settlement, Bouwcombinatie Sassevaart wanted to be on the safe side. What we do now prevents problems and saves money in the future."

Down to the last detail, everything is made extra waterproof

With the compartmentalized membrane system, the sills and maintenance tunnels will be made watertight. Application began in early October 2020, in the lock's outer head. Cousin: "The people applying the system have been trained by us. It was agreed with the construction consortium that only people trained by us would be allowed to do this work. The training took place in Utrecht, coronaproof via Teams, with the help of a trainer from Sika Netherlands and an expert from Slovenia."

How does it work?

Meanwhile, work on the outer abutment is over and the team has begun work on the inner abutment. "We are now in phase 1. What is unique for the Netherlands is the fact that the system consists of different compartments. These are injectable afterwards in case of calamities, which guarantees the high degree of watertightness," Breukers explains. "We are working in compartments of 150 m², bounded by a joint profile embedded in the concrete. Every 150 m² has five injection points, these come together with hoses, in a kind of "socket. Is water coming out of one of the hoses? Then injecting that hose with injectant is a quick, targeted solution."

The preparation for the work took longer and was more intensive than the work itself. "Compliments to the people at Sassevaart are definitely in order here," Cousin continued. "There is daily contact between Sika, Sassevaart and the applicators. Sassevaart, Gacon and Vilton are continuously working with eight to ten men. In total, we are talking about 4,000 m² to wall and floor being treated. The concrete structure is built from underwater concrete, then comes the work floor, then our waterproofing system consisting of geotextile, followed by the waterproof membrane Sikaplan wp 1100 - 31 HL 2. On this Sikaplan membrane the Sika joint tapes and injection points are placed. The seams are welded together fully automatically. A Sika protection sheet is also applied to prevent damage by, for example, reinforcement. According to protocol, everything is tested: the seams are pressed, we perform tests and record the results neatly in a logbook."

Waterproofing as an absolute specialty

"What we are doing in Terneuzen is customized work, founded on our expertise in waterproofing. The design was engineered in 3D, in consultation with Sassevaart and a team of specialists from Sika Corporate. We have a sublime collaboration with main contractor Ben Bosboom and project coordinator Joost van Kempen of Sassevaart. Phase 2 started on January 4. This way of working is sustainable and very redundant. Quality assurance is very important here, a reason why Sassevaart chose us. On May 14, 2019, the Senate passed the Building Quality Assurance Act (Wkb). That law aims to improve construction quality and construction supervision by engaging private quality assurance companies. It also expands the liability of contractors vis-à-vis private and professional clients. This law will take effect on Jan. 1, 2022."

In conclusion, Cousin says, "What we are doing now is unique by Dutch standards. The method we are now using gives a verifiable assurance of the waterproofing of the structure. Important, since we are dealing with a brackish water environment. Salt water is disastrous for the reinforcement present in the concrete. Contractor combination Sassevaart ensures a dry and safe concrete construction with this approach."