Construction World October 2016

ROADS AND BRIDGES

SMOOTH OPERATOR on N1 upgrade

This has certainly been the case on the upgrade of the stretch of the National Route 1 (N1) from Sydenham (km 28,8) to Glen Lyon (km 62,4). Once completed, the project will again highlight South African road construc- tion capabilities and, just as importantly, showcase the capabilities housed in the Raubex Group. The road will have an extremely high rideability specification, as well as a life- span of approximately 20 years, in line with consulting engineer, WorleyParsons’ design requirements. Contracted by the South African National Roads Agency SOC Limited (SANRAL), Raubex Construction and sister company, Roadmac Surfacing are making steady progress on this construction programme. The road comprises 350 mm of G4 stabi- The Raubex name is synonymous with quality road infrastructure. It therefore stands to reason that member companies of the largest road building specialist in the country will strive to exceed expectations in the immediate vicinity of its own headquarters in Bloemfontein, Free State. >

lised sub base, 120 mm of bitumen treated base (BTB) course and 20 mm of ultra-thin friction course (UTFC). Raubex is tasked with constructing the sub-base layers while Roadmac Surfacing oversees the BTB and UTFC components of the upgrade. Despite a few complexities, the consor- tium of Raubex companies is planning to hand over this project well ahead of its completion deadline in December 2016. This follows almost 18 months of building activi- ties on this important national road artery. Reasons for solid track record Wimpie Koch, contracts manager of Roadmac Surfacing, attributes the sound track record of the company to a number of factors. Firstly, the company made a solid start right from the outset. When Raubex started with its component of the works, Roadmac Surfacing immediately commenced with the design of the asphalt. At the same Petra Quarries, owned and operated by Raumix Aggregates, and B&E International started producing and stockpiling the 26 mm BTB aggregate needed for the base layer, while National Asphalt commenced crushing the high specification UTFC aggregate required for the contract. These companies are part of Raumix, the materials division of the Raubex Group, and they were also joined by sister company, Tosas, which supplied the bitumen emulsions. Recycled asphalt Koch tells Construction World that the asphalt mix design comprises a high percentage of recycled asphalt (RA) – in line with govern- ment’s ‘green’ infrastructure movement. Initially, the professional team believed that it would be able to exceed these

requirements and, with input from Roadmac Surfacing, the BTB asphalt supplier bought a state-of-the-art batching plant that is able to produce asphalt containing a 40% RA. As much as 5 000 tons of asphalt comprising this high percentage of recy- cled pavement was placed in the very early stages of the contract. However, the quality of material recovered in the fast lanes of the N1 highway was insufficient and Roadmac Surfacing decided to lower the percentage of RA used in the asphalt mix. Despite this, Roadmac Surfacing has exceeded SANRAL’s expectations. “At present, we are placing an asphalt mix with a 30% RA component, which is significantly more than our client expected,” says Koch. “While introducing a second team to undertake asphalt batching activities at the batching plant may have come at an extra cost, the time savings were well worth it. We were able to gain at least a six week head start on this project by implementing these interventions,” he says. Koch says the biggest challenge on this project was the smoothing over of produc- tion challenges at the new plant. This was essential, considering that asphalt produc- tion is on the critical path of the entire contract. “The accuracy of the final layer of the BTB is critical, as it will influence the layer of UTFC that is placed on top of it, and if not 100% could compromise the high

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rideability specification demanded by SANRAL.”

Asphalt is batched in a state-of-the-art plant that is able to produce asphalt with a RA content.

CONSTRUCTION WORLD OCTOBER 2016