CONCRETE ADMIXTURES FOR RARE EARTH CORE DAM

When consultancy MBB Services Int'l was appointed for the detailed design of Ludeke Dam, situated in Mbizana in the Eastern Cape (South Africa), their engineers approved Sika to supply the concrete admixture for the first phase of the project.

WATER SUPPLY VIA LUDEKE DAM

Ludeke Dam, pump station and rising main form the raw water components of the Mbizana Bulk Water Supply Scheme initiated by Umgeni Water. Stretching 240 meters in length and standing almost 40 meters high, the dam will hold in excess of 14.5 million cubic meters, providing supply of water to surrounding communities consisting of 266'000 people.

The new Dam is an earth core dam - the dam wall comprising a clay-cored rockfill embankment with a concrete-lined side channel spillway. The pump station will supply water through a 13.9 kilometers steel pipeline to an existing water treatment works. The estimated earthworks volume is approximately 600'000 cubic meters.

CONCRETE ADMIXTURES BY SIKA

Sika supplied SikaPlast®- V210 as the concrete admixture used to construct firstly the base of the intake towers of the dam, then the entire structure of the intake towers, as well as all the spillways. SikaPlast®-V210 is a multi-purpose water reducer and superplasticiser utilizing the Sika® ViscoCrete® polycarboxylate polymer technology. Chosen for its qualities of versatility, good slump retention and optimised mix design, SikaPlast®- V210 does not contain formaldehyde, calcium chloride or any other chlorides and will not initiate or promote the corrosion of steel present in the concrete.

CONGESTED STEEL REINFORCEMENT

The first major challenge encountered by the contractor, Rumdel Cape, was the pouring of the concrete mixture for the base of the intake towers. Due to heavily congested steel reinforcement, as well as the difficult conditions on site, pumps and a crane had to be utilized to continuously pour 580 cubic metres of concrete; a job which took 27 hours to complete, far longer than any standard pour of concrete.