Gunsite Sea Defence Extension
Location:
Jersey
Country:
Jersey
Project Type:
Civil / Infrastructure | Marine
Project Scale:
0 – 5,000 m²
Adding Life to Concrete – How MARKHAM applied hydrogel systems to a Sea Defence Wall on Jersey.
OBJECTIVE
The existing military defence wall was originally constructed in the 1940’s and had no “recurve” section at the top. Due to rising sea levels, these walls were struggling to cope with large waves during storm surges. To resolve this, work was undertaken to construct a new section on top of the existing wall, that would both increase the height and provide a recurve profile.
MARKHAM were asked to provide a treatment process that would protect the new and existing concrete and reduce ongoing corrosion but also, to reduce the risk of incipient anode syndrome, where the old chloride contaminated concrete could react with / reject the new concrete.
SOLUTION
The most common solution in this type of situation would be to apply the AQURON 7000 system as this deals with rebar corrosion within the structure.
However, because the old concrete contained very little steel rebar, the AQURON 7000 was over-specified for this project. Consequently, the MARKHAM system put forward to achieve these goals was the spray application of AQURON 2000. This retro spray application provides a reduction in chloride levels within the concrete, mitigates the risk of spalling and increases durability and abrasion resistance.
RESULTS
The application of AQURON 2000 was a very rapid and cost-effective solution for chloride control and durability enhancement for the sections of the wall that were treated.
Due to its very surface-tolerant and weather-tolerant characteristics, the application of AQURON 2000 was completed despite rain at times, and without the tide changes negatively affecting the treatment.
Because it has a depth of penetration of up to 125mm, the AQURON 2000 is present within the matrix of the concrete for the lifespan of the concrete, making it a maintenance free solution that won’t require any further applications. With this depth of penetration, the fact that the application of AQURON 2000 does not change the physical appearance of the concrete in any way was a distinct advantage in preserving the natural concrete appearance of this historical structure. It ensured that there was minimal visual impact as a result of these works.
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Project Details – Gunsite Sea Defence Extension | |
Description | Concrete Sea Wall requiring chloride control and corrosion reduction to extend the lifespan of the structure and reduce the risk of incipient anode syndrome between old and new and repaired sections of the wall. |
Area Treated | 1,750m² |
Age of Structure | 80 years |
Requirements | Corrosion reduction Mitigation of incipient anode syndrome Zero Maintenance Minimum interruption to construction schedule |
Operation Downtime / Interruptions | All areas were treated after construction work was complete and as the areas could be put back into use immediately. As a result the application works had minimal negative impact on the project schedule. |
Application Method | High Pressure Airless Sprayer |
Proposed Further Works | No further works required. |
OHS Requirements | AQURON is nil VOC. No product-specific PPE required |
Historical detail!
The original Gunsite seawall was constructed by the invaders during WWII occupation, as anti-tank defence.
To dig deeper into the needs of marine projects, try our on-demand webinar “The Marine Concrete Experience“.
Additional images by WSP | Parsons Brinckerhoff
