Civil Engineering July 2021 | Vol 29 No 6

On the cover T he Raubex Construction and Roadmac Surfacing Cape Joint Venture (RBX / RMSC JV) project will consume around 180 000 bags of AfriSam’s Roadstab cement for the stabili- sation of the road’s G4 sub-base layer, and around 2 000 bags of AfriSam’s flagship All Purpose Cement for various ancillary concrete works. The project – commissioned by SANRAL – kicked off with a three- month site mobilisation which began on 15 July last year, and work has since been proceeding apace. Completion of the 30-month contract is scheduled for April 2023. Design consultants for this project are KBK Engineers, while the project supervision is being undertaken by SNA Civil and Structural Engineers. The contract covers 18 km of roadway on the R67/5 route, from the Swart Kei River Bridge in the south to Queenstown in the north. A complete rehabilitation is underway which will see the road upgraded and widened. The work also includes the building of one new bridge and the widening of another. Road widening means that the road’s existing 3 m per lane width will be extended to 3.7 m per lane, plus a 3 m surfaced shoulder and rounding off on each side. Some vertical realignment is taking place, such as at those areas where drainage problems are being addressed, where livestock crossings are required and at the new Swart Kei River Bridge. This realignment will improve line of sight for motorists, allowing the authorities to raise the current 80 km/h speed limit to 100 km/h. The horizontal alignment of the new road will generally follow the current horizontal alignment, with the only alteration taking place in the region of the Swart Kei River Bridge – about 1.3 km of road between staked km 14.90 and km 16.20. FULL-WIDTH CONSTRUCTION Facilitating the construction process is a 5 km long forward section (section 4) starting about 3 km south of Queenstown (around staked km 30) and extending to km 25, where a gravel wearing course farm access road has been prepared for the temporary deviation of traffic. This allows road building on this section to be conducted at full width, speeding up production rates. To expedite the process, well-planned excavation allows the culverts to be completed as quickly as possible. The section will be completed within a time-barred period of 18 months, starting March 2021. Major fills in the section are also being addressed in good time with the necessary cut-and-fill work. Pulverised material from the existing road can be used for fill, and in some sections even as a lower selected layer after it has been successfully tested as suitable G6 material. About 700 m 3 per day of material is moved to level out the road, allowing the contractors to proceed timeously to the layer works – the lower selected and upper selected layers. These comprise an imported G5 crushed gravel material of 300 mm, which is compacted to 95% of modified AASHTO density. This is followed by a 300 mm thick G4 sub-base layer which is stabilised with AfriSam’s Roadstab cement product. The 150 mm base layer is of G1 imported crushed stone, compacted to 88% of apparent relative density; the road Stability from AfriSam on Raubex‑Roadmac JV road contract A joint venture between Raubex Construction and Roadmac Surfacing Cape is making good progress on rehabilitating a portion of the busy R67/5 road between Queenstown and Whittlesea in the Eastern Cape, partnering for its cement products with construction materials leader AfriSam. 6 July 2021 Civil Engineering The contract covers 18 km of roadway and will see the road upgraded and widened