Caterpillar's Passion for Paving

Incredibly, much more is needed; the Trans-European Transport Network, known as the TEN-T, calls for many more roads as part of a policy to develop a more efficient transport infrastructure across the European Union.

High-quality highways are demanded, and there is a sense of urgency, with European authorities targeting completion of the core network by 2050.

At the same time, there are major problems with ageing road networks across Europe, and road rehabilitation is required at an increasing rate.

To deal with the huge demand for new roads and road repairs, construction businesses are investing in equipment that can efficiently deliver smooth, consistent surfaces.

And as materials prices continue to rise and the skilled workforce diminishes, construction businesses are looking to reliable and productive equipment, to ensure maximum profitability on road projects.

These machines often need to be robust enough to cope with the rigours of roadwork applications at altitude, in extreme weathers and on challenging terrain.

They must also feature the technology to ensure optimal delivery and minimal waste, in terms of both materials and time. The paving division of Caterpillar focuses on road construction, which boasts a wide range of equipment, from reclaimers and compactors, to pavers and cold planers.

As soil compaction must be completed before other phases of road construction can proceed, it’s vital that compaction equipment is both efficient and reliable.

Caterpillar boasts 14 models of vibratory soil compactors, with operating weights from below 10,500kg up to almost 19,000kg, including both smooth and padfoot configurations. The product line includes both standard and performance models, to match application and usage.

Taking the CS13 GC as an example, the machine’s performance revolves around an exclusive eccentric weight design, that improves reliability and reduces noise. The machine’s auto-vibe function also aids consistent compaction.

As an option, the 12,655kg smooth drum machine can make use of a padfoot shell kit, which allows for compaction of semi-cohesive or cohesive soil applications.

David Fabro, paving business development manager at Caterpillar, says of the Cat GC vibratory soil compactor line, “Operator comfort and ease of use were primary design drivers with these machines.

“It has an ISO-mounted cab and rubber floormats that helps reduce noise and vibration and operators like the intuitive controls layout and the levels of comfort, especially with the option of the air suspension seat.”

On rehabilitation projects, where deteriorated roadways must be stabilised, road reclaimers will pulverise the original asphalt layer and mixing it with the base material.

The reclaimers add asphalt emulsions or other binding agents, either during pulverisation or during a separate mix pass.

The process provides a homogenous material on which to lay a surface course, and is a crucial stage, ahead of laying asphalt.

If full-depth reclamation and soil stabilisation is required, machines need to be powerful robust and efficient.

The Cat road reclaimers line comprises the smaller RM400 and RM500 models, as well as the large RM600 and RM800 models, both of which are powered by powerful Cat Stage V engines.

Visibility of operators is a key feature of the machine, along with enhanced manoeuvrability.

Rolf af Klinteberg, a product application specialist with Caterpillar, says of the RM600 and RM800, “Sight lines are optimised with a full left-to-right sliding cab, meaning visibility to the cutting path is excellent, with floor to ceiling glass and an angled pane on the right-hand side that gives a clear view to the leading edge of the cutting chamber”.

On rehabilitation projects, where deteriorated roadways must be stabilised, road reclaimers will pulverise the original asphalt layer and mixing it with the base material.

The reclaimers add asphalt emulsions or other binding agents, either during pulverisation or during a separate mix pass.

The process provides a homogenous material on which to lay a surface course, and is a crucial stage, ahead of laying asphalt.

If full-depth reclamation and soil stabilisation is required, machines need to be powerful robust and efficient.

The Cat road reclaimers line comprises the smaller RM400 and RM500 models, as well as the large RM600 and RM800 models, both of which are powered by powerful Cat Stage V engines.

Visibility of operators is a key feature of the machine, along with enhanced manoeuvrability.

Rolf af Klinteberg, a product application specialist with Caterpillar, says of the RM600 and RM800, “Sight lines are optimised with a full left-to-right sliding cab, meaning visibility to the cutting path is excellent, with floor to ceiling glass and an angled pane on the right-hand side that gives a clear view to the leading edge of the cutting chamber”.

“They’re easy to set up and very versatile, which is perfect for highways, airports and mid-sized applications.”

The compact dimensions and relatively light weight of these pavers makes them easily transportable, as well as being highly manoeuvrable on site. The AP400’s operating weight is 14,581kg, while the AP500 weighs in at 15,430kg.

Both wheeled paver models can travel up to 16km/h and can be fitted with front-wheel assist, with an extra option on the AP500 of all-wheel drive, which Fabro says can be “beneficial when pushing heavy loads”. Both tracked paver models are recommended on softer base materials and with a 6km/h transport speed for the steel track version and up to 11 km/h for the Mobil-trac System.

Whether using hot or warm mix asphalt, there can be no delay in compaction once the asphalt is laid down. To ensure the removal of air voids from the structure, the density of the road surface must be increased – usually by an average of 10-15% – to ensure the maximum lifespan of the road.

“This is a critical element of the road construction process,” stresses Rolf af Klinteberg, “as you need to strike the right balance between compaction, smoothness and speed. If the roller’s drum is too narrow, it will take too many passes to completely cover the paved surface; if it’s too wide, it could lead to non-uniform density, with compaction runs overlapping.”

To this end, Caterpillar manufactures a wide range of tandem vibratory rollers, from as little as 1.6 tonnes to over 16 tonnes.

At the larger end of the series, the CB7, 8 and 10 can have ROPS or fully-enclosed cabs and are designed to tackle intermediate applications, including urban streets and highways.

These fuel-efficient machines come with Eco-mode and automatic idle shutdown and are simple to operate, with straightforward dial indicators and an intuitive touchscreen display.

At the same time, there is no shortage of onboard technology, including compaction control and flexible vibratory systems.

One of the first machines on site can also be the final piece in the road construction puzzle – cold planing.

All roads have a finite lifespan, at the end of which, they may have to be rehabilitated, generally beginning with a milling or planing process.

Depending on the amount of damage the asphalt has suffered, a cold planer is often used, either to remove part of the existing pavement to help restore a smooth surface, or to remove the full depth of asphalt, along with the sub-base materials.

Getting the right machine for the job is key, according to David Fabro, who says, “Cold planing machines must be heavy enough to provide the traction and stability required to remove the required depth of pavement surface.

“Our large cold planers use integrated technology to achieve milling precision, along with System K rotors and a Cat track design with advanced steering and traction control.”

At the heavier end of Cat’s cold planers are the PM600 and PM800-Series models. These machines can mill from widths of 2010mm to 2505mm.

The PM620 has an operating weight of over 33 tonnes, and a gross power rating from its Cat C18 engine of 474kW/636 HP.

These are powerful and heavy machines, but are able to cut through road surfaces with extreme precision. Equipped with automated grade control systems, the cold planers can mill accurately to specified elevations, grades or cross-slopes.

The largest cold planer in the series is the PM825, which weighs in at 37.5 tonnes and features a 601kW/806HP C18 twin turbo engine, providing 21% more gross power than the PM620, based on standard engine performance testing.

This high-production, half-lane machine is designed with the capacity to complete a controlled full-depth removal of asphalt and concrete pavements in a single pass.

Cold planers are heavy duty machines, designed to operate under the most challenging conditions. It is imperative that their critical components are both robust and accessible for servicing and maintenance.

A prominent feature of a Cat cold planer is its System K rotor, designed to minimise wear and maximise material flow, with a cutting pattern that moves material from the outside to the centre, for extraction.

The toolholder and base block elements of the rotor are made from abrasion-resistant high-strength alloys, while the large heat-treated surface areas on the toolholder protect the base block, increasing its useable life.