Construction World May 2019

DAMS & RESERVOIRS

MAJOR REFURBISHMENT FOR CORNELIS RIVER DAM

The Phumelela Local Municipality has been recently experiencing severe water shortages and has considered options to ensure the provision of a sufficient and sustainable potable water system for the future for both the short and longer term. Water usage has been restricted throughout the past years, but water quality deteriorates on a daily basis.

T he high rural to urban migration and changing water use pattern, mainly as a result of the introduction of water borne sewerage systems under the bucket eradication program place additional stress on existing infrastructure and resources. The final objective of this project was to implement a sustainable regional bulk water supply scheme in the Phumelela Local Municipal area, prioritizing the Warden region. The Cornelis River Dam, situated in the Free State between Johannesburg and Durban, 56 km North of Harrismith has undergone major refurbishment. The project commenced in October 2016 by contractors Raubex Construction, and was completed in the allotted timeline by July 2018. Sika’s reputable range of concrete repair and protection products were the top choice of specified products by project managers, Rudnat Projects CC. The Dam, which was completed in July, spans 23 metres in length with the wall measures 205 metres in height. It has a storage capacity at spillway level of 4 500 000 cubic metres. Construction technology innovation BHM readymix, situated in Harrismith, supplied all the concrete using our admixtures SikaPlast V220 and Stallion-2. In order to grout the

anchor rods into the rock, before pouring the concrete to create the steps. Intraplast-Z was used, a grouting admixture that is designed to introduce micro bubbles into the grout mix, thereby creating wet volume expansion and to increase fluidity without segregation. As a curing agent to prevent premature water loss, Sika’s Antisol-E was sprayed onto areas of mass concrete. Forming a thin film barrier, this ready to use liquid curing compound does not disturb the normal setting action of concrete which is then allowed to cure and achieve maximum properties. Separol-GU, an oil based release agent used to provide easy release properties to the formwork and permitting a high quality surface finish of the dam wall. Sika micro fibres were specified to be used in the spill way concrete as well as in the concrete mix of the dam wall to reduce any crack tendencies in early-age concrete. The structure was primed with Sikagard-550 W Primer, prior to the application of Sikagard-550 W Elastic, an acrylic based emulsion, high-build, and protective coating providing a durable covering with excellent resistance to weathering. As a surface hardener for concrete, Sikafloor CureHard-24 was used in the spillway concrete. This easy to apply compound reduces dusting of concrete as well as improves chemical and abrasion

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CONSTRUCTION WORLD MAY 2019