Raubex Construction’s new Cat RM500 rotary mixer forms the backbone of the road reclamation and stabilisation works
on Section 19.

Part of an extensive motorway network measuring some 185km, the ongoing Gauteng Freeway Improvement Project (GIFP) is
being implemented in stages by the South African National Roads Authority (SANRAL) , creating a modern, world class toll route
system in South Africa’s most populous and commercially active region.

National Route 12 (N12) is one of SANRAL’s strategic priorities and it is here that civil engineering contractor, Raubex Construction,
has been awarded the task of implementing a complete overhaul on Section 19. The scope of works involves an intensive
programme running over 30 months and calls for an emulsion and cement stabilisation mix for the sub-base layers.

Three major new interchanges, successive bridge widenings and an east and westbound three lane highway in either direction
will replace the existing N12 dual carriageway system along approximately 10km between the current Tom Jones and Daveyton
on- and off-ramps. For both the existing and new lanes, full depth reclamation and soil stabilisation will be carried out by Raubex’s recently acquired Cat RM500 rotary mixer. The RM500’s design incorporates separate water and emulsion pumps, which are simultaneously monitored in the cab via two separate flow meters.

With an operating weight of 28 145 kg, the RM500’s Cat C15 ACERT engine has a gross power output of 403 kW. Width of cut is
2 438 mm, whilst the maximum depth of cut is 457mm.

“We needed a high power to weight ratio on the N12 to cope with the existing varied in-situ premix materials, plus the dual mix
stabilisation design makes the RM500 the optimal choice,” explains Raubex Construction operations manager, Wouter van der
Merwe. With the RM500, Raubex will reclaim and stabilise the 300mm sub-base in one go along the demarcated sections.

The equipment team on the ETB section will comprise the Cat RM500, in addition to a Cat fleet that includes the latest generation
Cat 140K motor grader, plus Cat CS76 single drum 20 tonne vibratory rollers.

This will be a construction road train with the RM500 pushing ahead two tankers, one carrying 18 000 litres of emulsion and the
other 18 000 litres of water for the sub-base phase. The emulsion ratio will be between 2 to 3% and cement around 1,5 to 2%.
From a quantity perspective, the volumes on Section 19 are substantial. Raubex’s RM500 will be deployed for the sub-base
component, amounting to 135 000m3, whilst the selected 300mm layer comprises some 102 000m3. Some 9 million litres of
emulsion will be used, together with 5 000 tonnes of cement and 114 000 tonnes of BTB.

“What makes the N12 project particularly noteworthy is that all materials will be worked in-situ or sourced from cuttings that will
make way for the new lanes and interchanges along the route,” adds van der Merwe. “Achieving this requires very complex
planning to meet incremental timeframes.”