CRL recently completed a critical repair and refurbishment project on an above-ground water tank at a distribution service reservoir. Built in 1980, these circular tanks, each with a 49m diameter and domed concrete roof, required significant work to ensure their long-term durability and functionality. It is not known whether the roofs are of prestressed, or conventional reinforced concrete construction. The reservoirs consist of single cells each.
In February 2021 an inspection of the North reservoir (both external & internal) was carried out which identified a number of defects. CRL as one of the reservoir refurbishment framework contractors was asked to tender for the works and awarded the contract to undertake the repairs and refurbishment in March 2021.
The works were varied as is expected for an asset of this nature. Externally, a complete removal of the existing roof covering, and an application of a new fully bonded coating was required. This was in addition to sundry works such as hatch re-bedding, circumferential sealant joint replacement, sealing of cable entry points and drainage renewal. CRL played a major role in the development and approval of the Triflex MMA specification as the roof covering needed to meet a 20-year design life.
The waterproofing works involved removing the existing roof covering and installing a new membrane. The perimeter coating on the roofs, likely intended to demarcate an access path and provide anti-skid properties had deteriorated, showed significant signs of delamination, raising concerns about its effectiveness and safety. Additionally, there was evidence of cracking around the access hatches and the roofs surface drainage ports which necessitated comprehensive repairs.
CRL, in collaboration with Triflex, conducted thorough assessments of the existing substrates, including cohesion strength and adhesion tests on both coated and uncoated areas of the concrete roof. These tests were crucial in determining the appropriate preparation, priming, and waterproofing solutions to meet a 20-year design life.
After a thorough evaluation of the test results, Triflex ProTect, renowned for its strong adhesion to various substrates, including challenging surfaces was chosen as the appropriate system. Triflex ProTect utilizes reinforced PMMA resin technology, providing excellent waterproofing for all details such as flashings, upstands, and penetrations.
Perimeter Coating Removal: Tests revealed insufficient bonding of the existing perimeter coating to the concrete substrate. Therefore, CRL removed the deteriorating coating and installed the Triflex ProTect system directly on the concrete. The new system, embedded with anti-skid beads, created a fully bonded walkway solution, ensuring safe maintenance access.
Access Hatch Areas: The Triflex ProDetail was applied over the existing black coating around the hatches and the adhesion properties validated by on-site tests to confirm the bonding strengths. This reinforced system provided durable waterproofing for these critical areas.
Central Dome Preparation: The uncoated area of the dome was cleaned by jet washing, and all cracks were over-banded with high tensile strength reinforcement fleece. The concrete was then primed and overlaid with the reinforced Triflex ProTect system. The slope of the roof necessitated the use of a liquid thixo agent, ensuring an even application of the membrane without slumping.
Despite the complexities, the Triflex ProTect system, enhanced with a liquid thixo agent, retained its rapid curing properties. The waterproofing membrane was rainproof within 30 minutes and fully cured in an hour, ensuring minimal disruption. All works were executed to the highest standards by CRL.
Internally, the works included extensive removal and replacement of wall and floor joint overbanding, access gantry survey and refurbishment, concrete repairs, installation of safety gratings, cleaning, and disinfection. The internal works required a significant large, designed scaffolding to provide access to the entire circumference of the tank, in a particular sequence and programmed to meet the delivery date. With CRL’s tried and trusted supply chain, and a workforce structure that offers flexibility in how we respond to the needs of our clients we were able to respond to the short mobilisation and programme period to successfully deliver a project of this nature.
This project underscores Concrete Repairs Limited's expertise in concrete repairs and their commitment to using innovative solutions for long-lasting results. The partnership with Triflex enabled CRL to deliver a comprehensive waterproofing system that not only enhanced the structural integrity and safety of the water storage tanks but also ensured their continued service for many years to come.
CRL's meticulous approach ensured the refurbishment project not only met but exceeded the required specifications, with the works being completed on time and to the client’s satisfaction.
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