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.

The structures at Colonsay remain strong and in position, as NATCEM® 35 performed exactly as required. Moreover, the underwater works formed a critical part of the wider project, which has now been hailed a success:

• Both berths at Kennacraig are now fully operational, as confirmed by CMAL.

• Furthermore, CMAL’s Nasir Uddin praised the “tremendous efforts and cooperation” across all parties.

• In addition, George Leslie’s Tony Fry credited collaboration and careful planning for the seamless upgrade.

• NATCEM® 35 also proved its value as a reliable material choice in challenging, real-world marine conditions.

• Ultimately, the New Islay Vessel Enabling Works stand as a strong example of modern, sustainable civil engineering, where specialist products like NATCEM® 35 helped deliver durable infrastructure with minimal environmental disruption.