Rijnhaven: the demolitions

"Working from the water is a different discipline."

The demolition and subsequent processing of materials from the old maritime infrastructure of the Rijnhaven called on the expertise of the Adex Group, a renowned specialist in circular demolition. With major infrastructure sites such as the Royers Lock in Antwerp or the widening of the A9 near Amsterdam, the Adex Group was able to present gleaming letters of nobility. After working from the water in a first phase, the Rotterdam yard is now in the second part of dismantling. The company is transporting the materials for reuse to the nearby municipal yard in the Keilehaven. 

Demolition today is no longer about destroying, but about revaluing. This is also the policy and core activity of the Adex Group which, because of its focus on sustainability, is an important partner of the Rijnhaven project. Their required demolition works for the reconstruction of the harbor dock are in an intermediate phase. "The first phase, from the water, was ready by the end of 2022," says project manager at the Adex Group Willem-Jan Wagteveld. "For this, we brought in a 50-ton crane that approached the quays to be removed on a 50-by-14-meter pontoon. Using auxiliary pontoons, the wooden purlins and stairs were first dismantled and then transported to the municipal yard on the Keilehaven, for reuse. Next, our crane started to remove the granite deck gaps and basalt cladding. Part of that too was taken to the municipal yard in storage."

"Working from the water is a different discipline," Willem-Jan continues. "Especially the tidal effect of about one and a half meters is important to take into account in your planning. By planning our work well around the tides, everything actually went smoothly." Because the works proceeded from the water in the first phase, there was no vibration and noise nuisance on the surrounding area. For other scenarios - such as the protection of the old lock building during the demolition works of the Royers Lock in Antwerp - the Adex Group uses high-tech sensor protection to monitor the impact of the works and make adjustments if necessary.

Second phase on dry land

In Rotterdam, meanwhile, work continues from the filled-in dock, which entails a different plan of action. The demolition company has already processed 1,793 tons of materials, most of which are concrete and rubble (1,250 tons), basalt (320 tons) and hardwood (172 tons), all of which will be separated and reused in high quality. Much of that material was removed by the CAT352NG, which meets Tier 4 Final/Stage V emissions standards with a maximum excavation depth of 8.7 meters. Through automatic reporting, consumption and running hours are checked off against pre-set limits. The demolition hammer is an Atlas Copco HB4100: 4.1 tons in other words.

One-to-one reuse

The second part of the demolition work is on the Hillemakade. "Given the working depth of 4.75 m1, work will be done in two excavation depths. Boskalis is taking care of the first excavation, to about the groundwater level. From there, we demolish the basalt blocks of the quay wall in sections of about 25 meters and slide through the work over a length of 100 meters to remove the remaining infrastructure from the second excavation depth," said Willem-Jan. "This is followed by the wooden floor and king piles after which everything is removed." For a recycling process that minimizes the inconvenience on the surrounding area, the debris is broken on site and the released aggregate is rearranged on site as a construction road.

High-quality reuse of the materials that are released is always the starting point within Adex Group's projects. In their work on buildings, that often means dismantling building components for immediate reuse; in infrastructure projects, it more often involves high-quality recycling. "With the right way of working, they manage to release clean streams from the projects, which are good for recycling," says commercial director at the Adex Group Axel Hendriks. Yet the company is proving more and more that direct reuse is also a solution in infra. "When demolishing the viaduct over the Keizer Karelweg in Amstelveen, for the construction of the A9, we sawed loose concrete girders that were reused in their full size at another location. Continuing to innovate, on reuse, but also for example on modern and emission-friendly equipment is an important pillar of our company," Axel concludes.