Ham Island Bridge Deck Waterproofing - Costain for Thames Water Bridge Deck structural waterproofing

Working in Partnership with Costain & Thames Water

Ham Island Bridge Deck Structural Waterproofing

Costain & Thames Water engineers specified Prokol Polymers for the Ham Island bridge deck waterproofing application; the bridge was located across the Thames at Royal Windsor.

The Bridge Was Tired & Desperately In Need of Refurbishment

The Scope of Works

The bridge had one single traffic lane & was the only means of access on and off the Island, all power and communication cables were in service channels at either side of the bridge. The problem for Costain & Thames Water was that the bridge could only be closed for a very limited time, It was at this point the engineers requested a technical survey from Prokol Polymers to solve the bridge waterproofing Issue with a fast cure advanced Polymer.

The Survey

Once the survey of the bridge had taken place the specification could then look to be constructed, taking into consideration all the key factors surrounding this very unique and sensitive project every aspect needed to be covered. Prokol & the approved applicator working with Costain and their client Thames Water looked at a well structure team plan to execute the deck waterproofing application.

The Prokol Specification - Steel Bridge Refurbishment

The bridge structural steel had to be rectified firstly as it was heavily corroded, The structural steel had to be prepared by captive blasting under encapsulated sealed scaffolding, a fresh clean profile was required to standard SA2 - SA2.5. This level of preparation would give an excellent bond strength for the new anti corrosion protection. Zinc primers were applied to the clean steel (SA2 2.5 Profile) then the entire bridge was coated in a final application of anti corrosive level C4 Prokol Ferroteq 960 High Solids Finishing Coating.

Prokol Polymers NBS Specification with 3D & 2D Detail Drawing Pack

Prokol Polymers Technical Surveyor Reviewing & Recording All Elements for Application Specification

Application & Quality Plan In Progress

Main Bridge Deck Road Membrane

The old road wear course had to be removed as the Prokol specification required the application to sit on the original concrete substrate, once the old surface had been removed a series of tests took place to ensure the integrity of the old concrete prior to any application. Once the existing substrate was hammer tested in a non destructive method some repairs in epoxy were required to make good the bridge deck before the waterproofing system could commence.

Removed Old Road Surface Removal

Fresh Repaired & Sound Concrete Substrate

Removing Surface Contamination & Concrete Latency

Once all substrate repairs were fully cured the next phase of dust controlled diamond grinding began, this was to remove any surface contamination from vehicles using the road during the preparation stage. Also latency from the new concrete had to be removed, as part of the quality plan calibrated adhesion pull tests were carried out on the new concrete to ensure the integrity of the substrate.

Dolly Firmly Bonded to The New Concrete for Independent NACE Calibrated Adhesion Testing

Dust Controlled Diamond Grinding

Moisture Testing the New Concrete

When new main traffic concrete section had been installed the concrete manufacturer states that you should leave it for 28 days to fully cure, as Prokol are very precise with their specifications we take no chances that could compromise the project and application. So following other manufacturer guidelines is paramount, the next step is to establish the level of moisture content in the cured concrete. Although the Prokol primer system & Pure Hydrophobic Polyurea is moisture tolerant, its essential to the required recording data moisture content is measured, The Prokol system will work with around 7% deck moisture without any issues.

Calibrated Moisture Testing Equipement

Independent NACE Coating Inspector

Prokol Concrete & Steel Primer Phase

With all test results positive as expected the next phase of Prokol primer application can begin, Prokol Primer ProFast RW was specified for its fast cure, (40 Minutes at 20 degrees C) and its moisture tolerant physical properties. Prokol specified a broadcast of kiln dried sand into the primer but require it to begin tacking off first, this to avoid the aggregate falling through the primer to the surface causing a possible weak bond between the primer and substrate. Also the sand bed on the primer it allows for a good mechanical key and foot traffic whilst it cures beneath, & should inclement weather be encountered the sand process will remove the need to re-apply another layer of primer. The Prokol ProFast RW Primer is also used on steel as well as concrete and has anti - corrosion properties, the primer forms a single application across the substrate laterally & terminates vertically 100mm onto the bridge facade creating a full tanking detail. Adhesion to concrete of the Prokol system is around 5 -7 mpa so very high bonding. This level of adhesion is required where heavy goods vehicles are in regular use of the bridge, highways standard is around 1.2 mpa, so this application adhesion was five times higher than that of the highways standard.

Primer & Sand Application

Approved Applicators Applying Kiln Dry Sand

Structural Bridge Deck Waterproofing Phase

Once the primer has cured the approved applicators apply a cheese wire cutting tape 100mm up the vertical bridge wall, this is where the Prokol structural waterproofing will terminate. A low level protect sheets sits just above this cutting wire to protect the fresh new bridge coating, once all the preparation is complete the final application of Prokol's fully Hydrophobic Pure Polyurea spray waterproofing membrane is applied. This application is carried out by highly skilled approved applicators with computerised application equipment, precision in finish and detail will be impeccable.

So What is the Difference Between Hydrophobic & Hydrophilic

Hydrophobic & Hydrophilic Waterproofing Explained

Prokol Hydrophobic Structural Waterproof Membrane

Once the approved applicator has applied a 3 mm DFT (dry film thickness) layer of Prokol CE Certified Hydrophobic Pure Polyurea, thickness checks are taken and recorded to ensure continuity of the coating layer. These thickness checks cross reference with the computerised application spray units consumption for accuracy. The Prokol structural waterproofing 136T Pure Polyurea has 330% elongation, so the vertical to lateral bridge joint plus any load deflection on the bridge is not a problem for this high performance coating.

Complete Waterproof Bridge Deck

Bridge Deck Waterproofing Complete Now For Further Membrane Water Tightness Testing

Once the membrane has cured (8 seconds 1 ton point load in 10 minutes) the final phase of testing begins, this testing is done by an independent NACE certified inspector with calibrated Holiday or ELD electronic leak detection equipment. To carry the ELD test an earth point is taken from the bridge up-stands and a low level electrical current is passed under the membrane through the concrete. As the Prokol Pure Polyurea 136T is a certified insulator against electrical current if any defects or pinholes exist in the coating a electrical spark will appear. Should a pinhole or defect be present in the coating the independent inspector will mark the area and the approved applicator will need to seamlessly fill and overcoat that section. It is then fully tested again before being signed off by the inspector and the main contractor. Once this quality control process is complete the coating is ready for the road tarmac wear coarse to be applied.

Independent Nace Coating Inspecting Electronically Testing the Membrane, this to to Ensure Full Integrity of the Waterproofing System Prior to Warranty Sign off By a Prokol Quality Technician

The Prokol 3 mm Membrane Had A 500 Micron Over Tolerance, (So 3.5 mm)This Was to Allow for Abrasion as a Key for a Colas Tarmac Adhesive to Be Applied For The Final Road Wear Layer

The Ham Island Bridge Fully Refurbished

The Bridge Was Delivered With No Delay On Time & On Budget

Prokol Polymers are an ISO Registered Company

www.prokol.co.uk - info@prokol.co.uk