Project: Concrete Repairs at Margate Treatments
Product: SHOTCRETE 513
Client: Southern Water
Contractor: Corroless Eastern
Specialist Sub-Contractor: GSSL
Perched in the cliffs of Margate, the town’s sewage treatment works looks more like a Bond villain’s lair than a utility plant. However, behind the dramatic exterior lay a serious problem—severe concrete degradation within the inlet chamber and Archimedes screw chambers.
Southern Water identified this issue during a major resilience upgrade, which also included replacing the Archimedes screws. Consequently, Corroless Eastern tendered for the repair works.
Before Corroless Eastern began, a concrete condition survey revealed significant sulphate contamination. Specifically, the report detailed how deep the concrete needed to be removed to reach uncontaminated material. As a result, this helped define the scope of the hydro-demolition work.
One key challenge was that the inlet chamber remained operational throughout. Therefore, to protect the treatment process, engineers installed screening at the base of the scaffold. This caught any debris released during the hydro-demolition phase.
Ultra High-Pressure (UHP) water jetting units removed the damaged concrete to the required depths. To confirm the success of this stage, teams collected dust samples and sent them for lab analysis to check sulphate levels.
With the damaged sections gone, teams uncovered heavily corroded steel reinforcement. In some areas, they needed to remove and replace entire sections of rebar to restore structural integrity.
For the repair work inside both the inlet and Archimedes screw chambers, the project specified Natural Cement’s SHOTCRETE® 513. This dry-spray concrete offers fast setting (initial set at 4 minutes, full set in 10), making it ideal for high-pressure, time-sensitive repairs.
Importantly, it’s environmentally friendly, DWI Reg.31 approved for use in potable water, and can be applied in cold and wet conditions. The product also features high chemical resistance and can be installed to virtually any thickness above 10mm.
GSSL, a specialist sprayed concrete subcontractor, applied the SHOTCRETE® 513. Throughout the process, they monitored the climate to ensure conditions remained suitable.
After application, they assessed the curing and strength of the repair using rebound hammers and lab-tested core samples. Once the concrete cured sufficiently, they applied an epoxy-modified cementitious coating in two layers as the final step.
The project ran in three phases over three years, including one mobilisation during the COVID-19 pandemic. Despite the difficult working environment and operational constraints, all parties involved delivered a successful outcome.
t: 01226 381133
e: enquiries@naturalcement.co.uk
Date added: 12/12/2023