CMA PAVING SEMINAR ATTRACTS OVER 200 DELEGATES :

Australian professor, Brian Shackel, gave an illuminating discourse on permeable paving. Other presenters included Pretoria University professor, Alex Visser, Alan Pearson, executive director of the Concrete Masonry Association of Australia (CMAA), and CMA director, John Cairns.

Professor Visser spoke on the deterioration of concrete paving blocks and Alan Pearson gave an entertaining photographic presentation on various aspects of precast concrete in Australia. It included masonry walling, paving and retaining block walls. John Cairns shared some insight on proposed changes to the standard for concrete block pavers, SANS 1058, which is in is in the final stages of being drafted by the CMA for submission to the South African Bureau of Standards (SABS). 
 
Interviewed after the seminar, Professor Shackel observed that although permeable paving technology was introduced into Australia in the early 1990s it is still in its infancy in that country. He says the main reason for this is resistance from engineers, most of whom were taught that paving should prevent and not promote water infiltration.

“We have found landscape architects far more willing to promote the system. Australia needs to conserve all the water it can. Large parts of the country receive little rain and most of the continent is currently experiencing a record fifth year of drought. New housing plans are only approved if they can show a 40% reduction in water usage and in many areas a rain water tank is mandatory. Permeable paving, which can channel water into storage tanks or the underground water table, can certainly help alleviate water shortages and, at the same time, remove most pollutants from the water that enters the pavements. However, a more pressing role for permeable paving is to assist Government’s urban consolidation policies in reducing the loads that would otherwise be placed on urban storm water systems,” says Shackel. 

Permeable paving is better established in Europe, especially in Germany and Austria where it has been used for the past 20 years at least. Shackel says the essential motivator for its use in Europe are the taxes levied on water run-off into storm water drainage systems.

“The recent flooding of major rivers such as the Rhine, Danube and Elbe has more to do with the extensive paving of urbanised areas than it has with excessive rainfall. Germany and other European countries levy a tax on estimated water run-off which is why permeable paving is finding increasing favour with the Europeans,” says Shackel.

Both motivators for the deployment of permeable paving apply in the case of South Africa where water is in short supply and where some storm water drainage systems were designed for lower than existing and projected urban densities. Inadequate storm water drainage led to the country’s first permeable paving contract using paving blocks earlier this year and more are likely to follow as the process of urban densification gathers momentum and the need to conserve water becomes increasingly apparent.

Professor Alex Visser, Professor Brian Shackel, Alan Pearson and John Cairns pose for the camera at the concrete block paving seminar hosted by the CMA in June.

Professor Brian Shackel and South African masonry expert, John Lane, seen together at the CMA’s paving seminar in June.

Some of  the 200 delegates who attended the CMA’s paving seminar in June.