The rehabilitation of the N12 concrete highway near Witbank, in Gauteng, is about 90% complete owing to the high quality of products chosen, says subcontractor KP Projects site supervisor Darin Phillips.

He highlights that diamond blades from construction equipment manufacturer Diamond Products are being used for the project. The initial products supplied were delivering a lower-than-expected performance. After an evaluation of the concrete and the application, new tooling was specified, thereby reducing cutting times and lowering costs. The appropriate blades were designed and supplied to match the hardness of the concrete and the per- formance required on this particular job.

Phillips adds that the project has run smoothly, owing to the absence of rain, which can critically affect the process of adding silicon for a watertight seal in joint areas.

Diamond Products director Darryl Gray says KP Projects used the tooling range that is relevant to the job size. By purpose-building the proper product the first time round, a much better yield is achieved and the cutting cost for each metre of large-scale projects is reduced.

The contract was awarded by the South African National Roads Agency in mid-2012. The project started in late December 2012 and is expected to be complete on December 6, 2013, with a total of 42 km of road rehabilitated and about 224 km of concrete cutting and jointing done.

Gray explains that the rehabilitation was necessary as the old silicon joints of the road were no longer watertight, which led to water ingress under the ground surface. This, in turn, resulted in the deterioration of the subbase, which can cause movement in the road surface, resulting in cracking and uneven road surfaces.

Further, he notes that another aspect of the rehabilitation project is the texturing of the road surface. This involves cutting grooves that are 4 mm deep, and 2 cm apart to increase the tyre traction of the road surface during wet weather conditions. This was done with a specially designed texturing machine and Diamond Products’ 350 mm GC77 cutting blades, along with the 600 mm RC38 diamond blades used for the complete removal of broken and failing panels, he adds.

Phillips notes that there are 67 people involved in the project, including ground staff and management.

He explains that diamond core drills and diamond blades are being used on the rehabilitation of the concrete highway. The diamond blades are used for either cutting or grinding the road surface and the core drills are used for either exploratory samples or drilling holes.

Gray says the successful rehabilitation of the N12 concrete road is a flagship project that KP Projects will use as a reference for further road rehabilitation.