Fifth trophy for Terraforce - Metrobuild , 01/11/2008
International precast concrete licensor Terraforce has secured its fifth trophy at the Concrete Manufacturers Association (CMA) gala dinner held in October 2008. The company has won this award in 1998, 2000, 2002 and 2006.
The award was shared with the Bridgeview suspended concrete floor slab project in Braamfontein, Johannesburg, which was entered by Echo Prestress. The judges believed that Suikerbossie Nek and Bridgeview were outstanding projects, both of which were worthy of the premier award, so instead of choosing one at the expense of the other, the decision was taken to split the honour.
Contractors
MD of Cathay Industries SA, Hans Wiegand, and president of the CMA, Garth Gregory, presented the award to Holger Rust of Terraforce and Andre Reeders and Neville Moolman of Dassenberg Retaining Systems, the contractors who installed the product.
Rheeder says, "We are very happy to be honoured with this distinction, and feel that the quality of the project warranted such reward. It was achallenging project that was solved sensitively and with a certain flair."
Terraforce also walked away with two regional awards for the Cape, two national awards and a special commendation for a project in Die Kelders Cave, where Terraforce L18 blocks were used to preserve a sensitive dig site.
Suikerbossie Nek-Hout Bay
This retaining wall project was initiated when two engineering firms, Jeffares & Green and Mike van Wieringen and Associates, were selected to investigate a cut slope failure at Suikerbossie Nek, situated above Victoria Road between Camps Bay and Hout Bay.
The engineers found that erosion and collapsing was caused by the angle of the slope. Over time, the slope had been rendered unstable through weathering, which reduced its surficial strength parameters. In addition, non-functional surface cut-off drains situated above the cut face had accelerated erosion and slip failure. Alack of regular maintenance had led to silting and vegetation growth in the drain, resulting in choking, with consequential over-topping.
Erosion activity
Civil engineer at Jeffares &Green, Duncan Murphy, says, "At some point erosion activity would have intersected the cut-off drain, and the formation of a large eroded gully in the cut face would have been the likely outcome. This could have resulted in the formation of a deep and irreparable gully extending a considerable way up the slope. Moreover, judging by the crack pattern in the head-scarp, a significant collapse onto the road during a period of high rainfall was imminent."
As the slope was large and curved, near-horizontal concrete infill walers were used at five metre intervals to fill the uneven spaces between adjacent panels. These were secured with anchor bars so that any possible pressure on the gabion wall would be reduced. Terrafixes' maximum laying density of 10 blocks per square metre was used to prevent lateral sliding. Thousands of water-wise indigenous plants, ground cover and bulbous species were planted, and these have started to relieve the nondescript appearance of the slope.
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