The massive R352-million Umgeni Interchange upgrade currently in progress along one of Durban’s arterial routes will be a feat of engineering skill when completed. Sika was proud to supply a varied selection of their internationally renowned products for this multi-bridge construction project.

Having successfully designed the bridges for the Gillooly’s Interchange in Gauteng, one of the busiest interchanges in the Southern Hemisphere, Consulting Engineers, Hatch Goba were commissioned by SANRAL in 2009 to design an upgrade for the old split-diamond, signalised intersection between the N2 (National Road) and the M19. The new design was for a free-flow directional four-level systems interchange; involving the construction of five new bridges and two pedestrian bridges, with two incremental launch bridges as prominent features. The project was awarded to main contractors Rumdel Cape and Mascon.

As both highways comprise major traffic routes, the emphasis on this project was to keep traffic disruption to an absolute minimum. Additional challenges were space constraints caused by the nearby Umngeni River and the adjacent residential and commercial developments. The standard segmental method of bridge building for two directional ramps at the intersection was therefore scrapped in favour of the innovative method known as incremental launch. This method entails building the entire bridge deck from one end of the structure and eliminating the need for formwork, thereby allowing traffic flow to continue uninterrupted.

The incremental launch technology involves sliding sections of bridge deck over special bearings, which are concrete blocks covered with stainless steel and reinforced elastomeric pads. The first such bridge constructed was 232m long, from Umgeni Road onto the N2 Northbound while the second one measured 205m long from the N2 Northbound onto Umgeni Road.

Metier Mixed Concrete supplied shotcrete for rock stabilisation of the Umgeni on-ramp to the N2 Southbound. Two Sika products were added to the shotcrete: SikaPlast V210, an aqueous polymer solution that is a multi-purpose water reducer and superplasticiser, and SikaTard-930, a retarding concrete admixture developed for the control of cement hydration. It can be used in wet or dry spray shotcrete where cement hydration of the concrete mix is prevented (for up to three days, if required).

Other Sika products supplied were: Sikadur-31 CF Normal was used on the base plates of the columns supporting the incremental launch to be used for the launch bridges. As a concrete curing compound, Sika Antisol-E was sprayed onto all bridge decks and columns to prevent premature water loss. Rugasol-2-Liquid was applied on all concrete pours to prevent cold joints and to allow a keyed surface for new concrete. Exposed rebars were protected by SikaTop-Armatec 110 EpoCem, an anti-corrosion coating and bonding agent that provides excellent adhesion to steel and concrete. Sika AnchorFix-3+ was used for bonding the rebars. SikaGrout-212 and Sika Rep LW were used for concrete repairs.

When construction on the R352million project commenced in March 2011, three of the neighboring communities benefitted greatly as local labour was used to fill 150 newly created jobs. The Umgeni Interchange upgrade, which is nearing completion, will significantly alleviate traffic congestion by allowing the free flow of approximately 14 000 vehicles during morning peak hour and approximately 16000 vehicles during afternoon peak hour.

By supplying numerous dependable, innovative products, Sika has played a vital role in this project. As one of the largest undertakings of its kind in South Africa, Hatch Goba believes it will set an international benchmark for any similar projects in the future.