Construction World March 2015

PROJECTS AND CONTRACTS

MAKING INROADS in KwaZulu-Natal Murray & Roberts Infrastructure has secured its first roadworks rehabilitation contracts in the province of KwaZulu-Natal for the South African National Roads Agency Limited (SANRAL). This is a major coup for the company, established after the integration of Concor Civils and Concor Roads & Earthworks into a new single business called Murray & Roberts Infrastructure.

ABOVE: Rolling and paving of the longitudinal joint. CENTRE: The new asphalt surface being laid down by the paving train, comprising a dumper truck, paving machine and tandem rollers. BOTTOM LEFT: The north-bound slow lane being milled prior to being replaced with new asphalt. BOTTOM RIGHT: The tack coat being sprayed onto the milled surface. “Recycling the old asphalt in this manner represents a significant cost saving in terms of bitumen and aggregate, as well as being highly sustainable.”

recipe. This has to be monitored closely as quality control is critical.” In terms of volumes, 21 000 t of continu- ously graded fine mix and 23 000 t of contin- uously graded medium mix will be used on Section 25, in addition to 555 000 m 2 of UTFC. A total of 33 500 t of continuously graded course mix and 535 000 m 2 of UTFC will be used on Section 23. Equipment on site includes a paver, a shuttle buggy, a milling machine, vibra- tory roller and water cart. Hooks says that Murray & Roberts Infrastructure has also been employing local labour in terms of SANRAL requirements.

“There are actually two contracts that have been awarded back to back to Murray & Roberts Infra- structure. While the coordination

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and planning of these simultaneous projects represents a challenge in terms of logistics, it is a significant testament to the capabilities and expertise of Murray & Roberts Infrastruc- ture,” Bennie Hook, project manager, says. The scope of work on both contracts consists of periodic maintenance of National Route 2 (N2). The first contract is a 22 km stretch, namely Section 23 from km 33 to km 55, which is roughly from the Umzinto River to the Umkomaas River. The second contract is a 14,5 km stretch, namely Section 25 from km 2,7 to 17,2, which is from where the N2 crosses the Umlaas Canal to what is known as the Spaghetti Junction. The first contract commenced in August 2014, with a duration of 16 months, while the second contract commenced in September 2014, with a duration of 14 months and an estimated completion date of November 2015. Commenting on the pavement specifica- tion, Hook says the projects consist of reha- bilitation work on the old road surface. This involves milling out a layer of the existing asphalt and replacing it with new material, followed by a final Ultra Thin Friction Course (UTFC) layer on top. A major feature of the project is the use of a Comar mobile asphalt plant from Much Asphalt, which is providing the Recycled Asphalt Pavement (RAP) mix for the projects. Both projects will use 40% RAP content. “Recycling the old asphalt in this manner represents a significant cost saving in terms of bitumen and aggregate, as well as being highly sustainable,” Hook comments. “A particular challenge has been posed by closely monitoring the binder content of the existing asphalt, due to various rehabil- itation work carried out over the years that has used different materials. “The project is pretty straightforward. However, obtaining the correct RAP mix is tricky, as the varying binder content of the old asphalt affects the ratios of the mix

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CONSTRUCTION WORLD MARCH 2015