North Portsea Island Phase 4b Update - Week 6

The walls at North Portsea Island Phase 4 are being formed using a textured formliner (mould), which provides shelter for marine life to colonise. Our coastal environmental project engineer Lucy Sheffield explains:

“We conducted a survey of what was on the foreshore and then we targeted each of those species with different holes, crevices and texturing in different areas - things seaweeds can hold onto, or for limpets to graze on.

“It’s all in the inter-tidal zone so when the tide goes out it’ll be exposed and you’ll be able to go and see it. It will take a number of years, but the idea is that the wall will be covered in seaweeds and when you lift them up you’ll find all the different creatures under there. So there’ll be crabs hiding, for example.”

Our team formed a concrete working group in advance of the works. This involved planning our work with the formliner and running trials to agree the formliner texture, concrete mix and finish.

As the wall texture is intricate, several challenges are presented. The moulds need to be looked after to ensure consistency of the finish (any bangs or notches will show in the finish). The concrete mix needs to be right to ensure the intricate texture of the mould is achieved. Plus, the formliners need to be prepared to ensure they will come away from the concrete without breaking off the textured pieces.