How do you give a performance driven durable road surface on a good surface while correcting minor undulations at a minimum cost?
In one particular case, a client approached us with the aforementioned conundrum; “I have a good 100 km Major District Road section and I want to prevent it from deteriorating it further. Its beyond a Microsurfacing, but I want to correct it quickly with an effective and long lasting treatment.”
After an assessment of ground conditions, traffic and materials, we identified the typical primary failure modes of the pavement as following:
- Problem 1: Delamination of the existing wearing course probably as a result of ineffective tack coating. This was identified characteristically in the lane wheel paths, where traditional tack coats are expected to be picked up by tipper and paver tyres before the mix is laid onto it.
- Problem 2: Ravelling was another challenge as the road was primarily tree-lined. With a reasonable amount of rainfall (amounting to ~150cm annually), it was visibly expected that the constant drip action from the leaves on the road would cause distress in traditional binders weakening the bonding within the mix and resulting in slow deterioration in the form of Ravelling.
- Problem 3: Oxidization of the surface had also affected resulted over the service life of the pavement. A typical factor that accelerates Oxidization of binders on such roads is the fact that so much organic and fine dust material is usually gets settled on these low volume pavements, that it results in faster ageing which result in faster ageing.
We took up these challenges by providing them a turn-key solution; ARTPave™ Ultra-thin Bituminous Overlays.
ARTPave™ Ultra-thin Bituminous Overlays are a 20mm Bituminous solution derived from Indian Specifications and updated to incorporate World Class Practices in Mix Design and Road Construction using tailor-made Performance-based materials and controlled detailed mix gradation.
The solution is combination of 3 treatments.
- High Performance trackless Tack Coat for enhanced bonding – Bond Coat
- Undulation/Delamination/Pothole-corrective pre-treatment
- 20mm of High Performance Bituminous Mix characterized by a Performance Grade Tailor-made Binder Solution custom developed for the challenges faced on the road with a highly controlled gradation
Treatment 1: High Performance trackless Tack Coat for enhanced bonding – Bond Coat
This treatment is a high rate of application of a premium trackless tack coat we call Bond Coat – designed for enhanced bonding of the ultra-thin layer with the existing surface. This was designed to counteract the challenge of Problem 1; delamination of wearing course when resulting from improper bonding with the base course, so similar problems aren’t faced in the future.
Treatment 2: Undulation/Delamination/Pothole-corrective pre-treatment
As a result of Problem 1 and intensified cases of Problem 2 (where ravelling had turned into potholes), this pre-treatment was necessary to bring the road up to a uniform level cross-sectionally to prevent issues such as differential compaction and enable successful use of a sensor paver to control the highly sensitive 20mm layer.
Treatment 3: 20mm of High Performance Bituminous Mix characterized by a Performance Grade Tailor-made Binder Solution custom developed for the challenges faced on the road with a highly controlled gradation.
As the final treatment to deliver a high quality pavement, we provided our ARTPave™ Ultra-thin Bituminous Overlays. This well graded mix with our MB3200 Performance Grade PG70-10V binder is deployed keeping in mind the specific requirements of the site. The bitumen rich mix is ideally suited to minimize oxidization and susceptibility to rainfall in this moderate region while maintaining strong bonding within the mix. This was done keeping in mind our specific requirement to minimize the risk of Ravelling. By ensuring adequate binder content resulting in sufficient film thickness, we will also battle out the oxidization threat to deliver a long lasting pavement as well as improved bonding for this Ultra-thin Hot Mix layer with the pre-existing road surface.
This project is undertaken with a 5 year Defect Liability Period!