Underwater Repairs with NATCEM® 35

Underwater Repairs with NATCEM® 35 are crucial for projects like the Colonsay harbour upgrade, where the grout sets without washout and provides long-term durability in challenging marine environments.

As part of the New Islay Vessel Enabling Works project, multiple Scottish harbour facilities required upgrades to accommodate CMAL’s new, larger ferries operating the Islay routes. The works included Kennacraig, Port Askaig, and Colonsay, with challenging marine conditions and tight operational schedules necessitating specialist civil engineering solutions.

George Leslie Ltd, working in partnership with Mott MacDonald, undertook the delivery of these vital infrastructure works on behalf of Caledonian Maritime Assets Limited (CMAL). Maintaining normal ferry operations throughout was a key project constraint, requiring strategic phasing and careful material selection.

Challenge

At Colonsay, a critical aspect of the works involved constructing underwater steel pile collars to weigh down and secure pier support structures. These collars, therefore, required filling with a grout that would:

• Set effectively underwater without washout.
• Be DWI Reg.31 approved for use in potable water environments.
• Offer long-term durability, even in challenging tidal marine conditions.
• Be efficiently installed, with divers required for precise placement.

Solution: Underwater Repairs with NATCEM® 35

For this challenging task, NATCEM® 35, Natural Cement’s rapid-setting, environmentally friendly grout, was the clear choice. Here’s why:

• It sets and gains strength underwater, with no risk of washout.
• Additionally, it holds Reg.31 approval, guaranteeing safety for both marine life and potable water.
• It boasts high early strength, which consequently accelerated the progress of the work.
• Moreover, it has minimal shrinkage and resistance to leaching, even in dynamic water conditions.

To verify the placement, divers from George Leslie Ltd used underwater cameras, providing real-time footage. As a result, the video below, on this page, clearly demonstrates how NATCEM® 35 securely forms the collars around the cylindrical steel piles — effectively holding them in place despite water movement and debris stirred by boat activity.