TODAY’S concrete roads are a far cry from the concrete pavements of old which are still in existence but were designed to very different design criteria to those employed currently.
That’s according to Bryan Perrie, CEO of Cement & Concrete SA (CCSA), who said early concrete roads were laid using obsolete techniques and equipment.
“Modern designs, new construction methods, better surface finishing, and high-tech machinery now make it possible to produce high-quality concrete pavement surfaces that satisfy the needs and objectives of road users, neighbouring communities, and road managers,” he said.
“Concrete pavements offer substantial environmental, economic, and social benefits and should be more widely regarded as the sustainable solution to South Africa’s road network. These roads, which undoubtedly offer lower whole-life cost for comparable design, are the natural choice for projects where performance, value, longevity, social responsibility and concern for the environment are paramount.”
He said concrete pavements also offer a long service life that normally exceeds 30 years and require relatively little maintenance and repair to produce long-term savings in raw materials, transport and energy. The reduction in traffic delays caused by road works on concrete pavements also cuts fuel consumption and exhaust gas emissions.
“In fact, at a time of soaring petrol prices, fuel saving for cars and goods vehicles is an important advantage of concrete roads that is not always apparent or published. Yet the facts testify to such cost savings.”
Sustainable concrete pavements make efficient use of natural resources and respect the environment throughout life cycles, he said, adding that these roads provide services to society in terms of mobility, safety and comfort by means of judicious choices when it comes to design, construction, maintenance and demolition.
He listed the following advantages and benefits of concrete for roads and pavements:
* Safety: Surface texturing of concrete pavement can improve water run-off so that traffic on wet roads does not cause splash, spray and skidding. The light colour of concrete pavements deflects light from vehicles and street lights, improving night-time visibility while effecting energy and materials savings by requiring fewer street lights per kilometre of road.
* Heat retention: Concrete roads reflect sunlight which helps to mitigate the ‘heat island’ effect. Research have shown that black surfaces exposed to sunlight can become 21ºC hotter than reflective white surfaces. This heats up the air around roads, contributing to increased temperatures in surrounding buildings, necessitating greater use of air conditioning, energy consumption and electricity demand.
* Labour-intensive construction: In countries, such as South Africa, where unemployment is a major burden to the economy, the manual aspects of the construction of concrete roads can be carried out by members of the local community after on-site training. Their newly-acquired skills can thereafter be utilised in other sectors of civil engineering.
Concrete roads can also offer better performance in areas with heavy loads and stop-start traffic, existing subgrade and alignment can be used, and existing deteriorated roads can be upgraded by overlaying or inlaying.
They can be built with integral kerb and channel, can reduce storm water reticulation, require simple, inexpensive equipment for construction and local materials can be used.
The require less lighting energy where streetlights are provided and can be built to offer built-in skid resistance and tined to improve drainage.
“A five-year Canadian study showed that concrete roads were only 2-4 decibels louder than asphalt. A conversation registers 60-70 decibels and a whisper, 20 decibels, so this is a minor and irrelevant factor,” Perrie said.
“Finally, on a smaller scale, South Africa also has yet to properly acknowledge the benefits of concrete strip roads which can be laid as wheel tracks, and are economic, durable and particularly suitable for rural areas.
“Concrete strip roads have proved successful in many countries but the SA governmental road building sector, as well as private land-owners, are still to fully exploit the advantages of such slim surfaces which can make steep rural roads passable in all weather.”