Two connecting quay walls will be constructed for the container terminal of Rotterdam World Gateway (RWG): a 1,250-m stretch of deepsea quay (for the large container ships) along Prinses Amaliahaven and a 650-m long barge/feeder quay (for inland shipping and smaller container ships) at the head of the terminal. A sea quay will also be constructed for APM Terminals. PUMA has outsourced this work to subcontractor BAVO Kademuren, a consortium of BAM Civiel and Van Hattum en Blankevoort.
The deepsea quay is a concrete structure in the shape of an L, the foundation of which is formed by so-called diaphragm walls, vibro-piles and MV piles. Work started on the construction of this quay in January 2010. The construction process takes the form of a ‘train': at the front of the train, the builders start by digging a trench, while at the other end, the bollards are placed on the quay. In-between, one can view all the phases of the construction process. The quays are being constructed in the newly sprayed-on sand. That is why more land has been sprayed on than will eventually be left over.
The panels from which the diaphragm wall is constructed are 38 m high, 1.2 m thick and 7.5 m wide. A trench is dug for these concrete walls using a digging bucket, a kind of grab connected to long steel cables. During the digging process, bentonite - a thick, clay-like liquid - is poured into the trench. Bentonite does not harden and gives sufficient support, preventing the excavated trench from caving in. Using bentonite means that the subcontractor doesn't have to use formwork and can pour concrete at great depths. Once the trench is sufficiently deep, the concrete reinforcement is positioned in the trench.
After this, concrete mixers pour concrete into the trench. A total of 300 m³ of concrete is required for each 7.5-m panel. Starting at the bottom, it is poured into the trench by means of a tremie pipe. As a result, the concrete pushes the bentonite mixture upwards, where it is collected for re-use. A characteristic of concrete is that it is strong under pressure, but is less able to withstand tensile force. This is why concrete is often reinforced. By incorporating a grid of iron rebars in the concrete, the reinforced concrete can deal with the (tensile) forces. Generally speaking, concrete consists of cement mixed with sand, gravel and water. Under the right conditions, concrete sets and acquires the strength of natural rock.
Most of the diaphragm structure is situated underground. In order to distribute the tensile forces of the quay structure, MV piles are driven into the ground at a diagonal angle to the wall. All in all, over 200 MV piles and more than 800 vibro-piles will be used for this container terminal.
Casting of the superstructure
On the landward side, the quay will be finished by positioning a concrete superstructure on the diaphragm wall. To build this L-wall, once the formwork has been constructed, concrete will be poured in 25-m segments. This superstructure will ensure that the quay has the necessary stiffness. After this, the fenders (bumpers) and bollards that will separate the vessels from the quay will be installed.
During the construction in 2006 of the quay wall for the Euromax Terminal in the Yangtzehaven, Hendriks precon developed a self-moving formwork vehicle for the L-shaped quay wall. The formwork, which was used to cast the floor and the wall in one go, proved very efficient. The acquired knowledge will be re-used in this project. The self-moving formwork vehicle allows the builders to pour a 25-m section of the quay wall every three days. To construct the total length of 1,250 m, some 1,000 m³ of concrete will be poured 44 times.
Once the quay walls for the deepsea port have been realised, the formwork with be dismantled, only to be reassembled some 4.5 km further on for the construction of another 1,100 m of composite walls for barge/feeder ships. For this job too, the formwork vehicle will be entirely self-supporting and fitted with its own electricity supply, hydraulics and cables.
To make sure that the quay structure can withstand the enormous forces that will be exerted on it by future container ships, the MV piles were subjected to a tensile test. In this test, the force was increased to over 92 tonnes. Ultimately, the structure has to be able to withstand 72 tonnes. The MV pile passed this test with flying colours.
Once the superstructure has been correctly positioned, the quay wall itself is finished. The quay is however still completely enclosed by the sand in which it was constructed. Once the waterfront has been dredged free and the port basin has been dredged to the required depth, the quay is ready for use.
The RWG barge/feeder quay for inland shipping consists of a concrete wall of 7 by 3 m, constructed on top of a foundation that incorporates a composite wall of tubular piles and steel sheet piling, with horizontal anchoring. The foundation of this quay was already constructed along the full stretch of 550 m in the summer of 2010. This was followed by the positioning of the concrete wall on top of the foundation.
Since January 2011, when the front section of the ‘train' finished work on the RWG quay wall, subcontractor BAVO Kademuren has been busy constructing the barge/feeder quays and the deepsea quay for APM Terminals. In terms of size, this quay is comparable to that of RWG. The subsequent development of this work site already started in the fall of 2010.
A total of 150 people are working on the excavation work, the reinforcement, the casting of concrete and the completion of the quay wall.