RAUBEX'S AP655D 'CUTS ITS TEETH' ON THE R21
Forming the main link from the centre of Pretoria to Johannesburg’s OR Tambo International Airport, National Route 21 (R21) is progressively being transformed into a four lane dual carriageway with the addition of two extra lanes in either direction. The project forms part of the South African National Roads Agency’s Gauteng Freeway Improvement Project (GFIP).
South African listed entity, Raubex Construction, was awarded the contract for Section 1 of the R21 in September 2008 at an estimated project value of R770 million. Starting at the Olifantsfontein Interchange (km 27,60) and ending at the Hans Strijdom Interchange (km 45,30), Raubex is scheduled to complete all phases by 28th May 2010, following 23 months of intensified road works.
The project’s scope includes rehabilitation and repair of the existing pavement; construction of lane widenings with a full depth pavement and crushed stone base; and construction of a 40mm asphalt surfacing with an ultra thin friction course (UTFC) overlay over the entire pavement.
“Further works include bridge widening and rehabilitation of existing bridges; drainage improvements and reinstatement; plus the installation of lighting along the total length of the road,” explains Raubex Construction’s managing director, Louis Raubenheimer, highlighting some of the construction challenges.
Earthworks amount to 252 000m³; layer works 415 000m³; stabilisation 127 000m³; asphalt surfacing 645 000m²; and UTFC 640 000m².
As with any road construction project, mechanisation is a critical component, with Raubex Construction deploying a comprehensive fleet of paving and compaction machines to meet the tight programme. These include Caterpillar and previous generation Bitelli units. (Caterpillar Inc acquired Italian original equipment manufacturer, Bitelli, in 2000), plus Raubex Construction’s recently acquired Cat AP655D asphalt paver, which cut its teeth on the R21 prior to being shipped to Namibia to work on a new Raubex contract. Supplied by sole southern African Caterpillar dealer, Barloworld Equipment, this was the first AP655D to be sold locally.
Commenting on the AP655D acquisition, Raubex Construction plant manager, Johann van der Merwe, says that, “In addition to the proven reliability of Cat’s pavers, we particularly like the fact that the AP655D is easy to control, which is advantageous in terms of training new operators. And it’s straightforward to install extras such as the Cat-approved Trimble surveying guidance system. Additionally, the AP655D is very stable, enabling us to put down a thick layer in one pass.”
The AP655D’s AS4251C double width hydraulic power extendible asphalt screed lays material to the desired width and depth while providing a smooth finish with initial compaction. The standard paving range is from 2,55m to 5m with a maximum paving width of 8m.
CAT AP655D TECHNICAL SPECS
A high production unit, the Cat AP655D is proving popular with contractors worldwide, with its advanced material handling system featuring independent conveyor and augers controls.
“Cat’s four pump material handling system eliminates the need for feeder valves and provides the most proven system in the paving industry,” explains Barloworld Equipment product manager, Johan Hartman. For best results, a controller precisely checks the speed of the augers and conveyors, and the conveyors’ speed can be set to provide the precise volume of material needed. Additionally, an optional power folding front apron enables good material flow and reduces cleanout time and effort. Adds Hartman: “The auger assembly can be hydraulically adjusted up to 215 mm, which promotes mat consistency and minimises segregation. The ability to raise the auger assembly also simplifies loading and unloading from the transport vehicle for rapid deployment from one site location to another.”