Rehabilitation of reservoir resounding success

by Ofentse Sefolo
Rehabilitation of reservoir resounding success

One of the country’s biggest reservoirs, situated in Reservoir Hills in KwaZulu-Natal and known as Durban Heights Reservoir 3, needed significant rehabilitation and repair, following a full diagnostic of the 350ml capacity concrete reservoir.

A variety of issues were identified but of interest was the existence of a micro-climate within the reservoir. It was noted that where the roof soffit at one point totally saturated, was found to be perfectly dry in a few hours. This micro-climate with wet dry cycles creates a favourable environment for contaminants resulting in corrosion and weakening concrete’s integrity.

Collaboration results in success
Given the reservoir’s importance, Umgeni Water approved the rehabilitation project. They appointed Royal Haskoning DHV as project engineers and Smart Civils Construction (Pty) Ltd for the specialised civil work, using Sika product solutions following significant product proposals and trials.

The team faced significant challenges, including having to find alternatives for accessing the roof structure. Thanks to the innovation of Smart Civils Construction, their construction of a special 550 ton scaffolding in a birdcage configuration allowed easy and safe access to a quarter section of the roof at a time.

To fulfil the intended task, a decision was made to use a range of Sika’s products to ensure that the repairs would withstand the test of time.

Products used include:
• Sika MonoTop 412 NFG as a repair mortar because of its unique properties as an excellent wet-spray mortar.
• Top Armatec-110 EpoCem as the primary rebar protective coating for the concrete repair to protect the reinforcing of steel and inhibit corrosion.
• Sika MonoTop-610 was used as a primer to the concrete substrate, given the difficult conditions.
• FerroGard-903 Plus corrosion inhibitor delays the start of corrosion and reduces the corrosion rate when it occurs. It also increases the service life of a reinforced concrete structure.
• SikaWrap-230C due to the age of the structure and minimal concrete cover.
• Sika Injection-307 is a low-viscosity, elastic polyacrylic injection resin that can be adjusted to set at a pre-determined time, forming a passivating permanently elastic matrix.
• FerroGard-903 Plus – a corrosion inhibitor that penetrates down to rebar level over time and forms a protective monomolecular layer on the surface of the reinforcing steel.

For more information, contact Sika South Africa:
Tel: +27 (31) 792 6500
Website: https://zaf.sika.com

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