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Significant increases in traffic loads and volumes have led to the need for long-life, low-maintenance solutions for the construction and maintenance of roads. The South African Bitumen Association (Sabita) has identified a French innovation, high-modulus asphalt (HiMA), as a possible technology solution.
Benoit Verhaeghe of the CSIR and peers from Sabita, the Asphalt Academy and a private company undertook a study tour to Europe recently to assess the viability of implementing HiMA locally and of transferring the associated technology. They visited the French companies Colas, Total and Shell, as well as the Transport Research Laboratory (TRL) in the UK. Specific learning obtained from the TRL was how to transfer and implement HiMA technology from France to another country.
HiMA is a hot-mix asphalt consisting of hard bitumen blended with a high binder content with good quality, fully-crushed aggregate. It is designed to combine good mechanical performance with water-resistance and durability. It is aimed at producing very durable, high performance materials for use in long-life road pavements carrying heavy traffic.
Sabita has now awarded the CSIR a two-year project to transfer and implement the technology in South Africa, which includes an assessment of technical viability; the adaptation of French testing protocols and HiMA specifications for use in South Africa; the validation of HiMA technology through accelerated pavement testing using the heavy vehicle simulator (HVS); and the drafting of technical guidelines and specifications for HiMA.
"We think HiMA has great potential for implementation in South Africa, and that it could be ideal as a long-life pavement for use in areas carrying heavy traffic, including airports," says Verhaeghe. "It presupposes, though, that current constraints are addressed, which include the ability to manufacture harder grades of binders in South Africa; to integrate HiMA in pavement design philosophy; to translate French mix design parameters into South African ones; the ability of asphalt contractors to manufacture and pave the material; and the ability to market HiMA technology to major decision-makers," comments Verhaeghe.
Places where HiMA can be used effectively include:
- Roads carrying heavy traffic, particularly where traffic is slow and channelled, such as on major bus routes
- Where heavy loads are carried, such as dedicated truck routes, loading bays and container terminals
- On airport runways and taxiways
- In 'boxed-in' pavements, such as those found in urban and peri-urban areas
- On new pavements as a base course layer
- In road rehabilitation.
Enquiries: CSIR Communication
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