For two decades the once popular tidal pool in Margate on the KwaZulu-Natal South Coast was non-functional but, thanks to the Margate Urban Renewal Project, it has now been restored to its former glory.
By supplying one of its highly effective admixtures, SikaPlast V210, as well as its Macro Fibres, Sika played a pivotal role in this challenging R1.8m project, planned and managed by Royal Haskoning DHV.
The contractor, Innovative Concrete Solutions, was responsible for the overall operation and Kencrete Readymix Concrete supplied the concrete, containing the SikaPlast V210 admixture.
SikaPlast V210 is a mid-range water reducer for pumped concrete flatwork as well as applications where superior finishing characteristics are required with low retardation. It utilises Sika’s ViscoCrete polycarboxylate polymer technology and is ideally suited for use with lean, harsh concrete mixes and concrete containing slag, fly ash or microsilica. It has been formulated to provide a controllable extended slump life with increased set times without significant loss in early strength development.
To commence the project, a cavity in the pool had to be plugged while the old slab was broken and removed. In order to achieve the required concrete strength, SikaPlast V210 was added to a blend of NPC Plus L and Protec Cements.
The mid range water reduction of SikaPlast V210 provides several advantages, including high early compressive strengths, increased strengths and more durable, dense concrete with reduced permeability. It does not contain formaldehyde, calcium chloride or any other added chlorides and will not initiate or promote the corrosion of steel present in the concrete.
After thirty years in a salt-water environment, the original reinforcing of the pool was completely corroded. To ensure sufficient reinforcement for the new pool structure, the addition of Sika Macro Fibres to the concrete was of utmost importance. The fibres used were 50mm in length with a ratio of 4kg of fibres/cube of concrete.
Sika Macro Fibres are structural synthetic fibres with an X-shaped surface area for maximum bonding in concrete. They are a cost-effective alternative to welded mesh and provide increased load bearing and energy absorption of concrete. They are safe and easy to use, provide a homogenous reinforcement and are corrosion resistant.
Due to the ocean tides, the biggest challenge facing the contractor was draining the 600m² pool at low tide everyday, then having just five hours in which to pour 150m3 of concrete before high tide once again filled the pool. A further challenge was pumping the concrete into the pool from 100m away due to restrictions of the concrete truck accessing the beach which Kencrete Readymix Concrete were able to solve by supplying a sufficiently long pump.
