WHO'S WHO IN ROADS
Concrete routes deliver durability and economy Concrete pavements are widely used globally to carry heavy loads and provide longlasting solutions for highways, airports, bridge decks, as well as low-volume municipal roads. Bryan Perrie, CEO of Cement & Concrete SA (CCSA), discusses the benefits. When did concrete emerge as a meaningful alternative to bituminous pavements? BP The world’s first concrete pavement was built in Inverness, Scotland, in 1865, while in Edinburgh there are still sections paved in 1872 that are in use today. The first modern concrete pavement in the USA was constructed in Bellefontaine, Idaho, in 1893 and is also still in service. Locally, concrete roads have been built in the Eastern Cape since the late 1920s and some by Italian prisoners of war in the North West province during and after the Second World War. A number of these roads are still functional. South Africa’s first modern concrete freeway was built on the N2 outside Cape Town in the late 1960s and some parts are still in use.
What are the major advantages of concrete pavements? There are significant advantages from a construction, economy, health and safety, and performance perspective, some of which are listed below. Key economic benefits: • comparable initial costs for equal designs in other materials • lower life-cycle costs for comparable designs • very low maintenance and user disruption costs • reduced fuel costs for trucks • reduced stormwater reticulation if needed • ideal for upgrading existing deteriorated roads by overlaying. Performance benefits: • long service life • resists oil and fuel spillages • does not rut, shove or corrugate • easy to repair and maintain.
38
IMIESA April 2021
Construction benefit: • Labour-friendly – i.e. ideally suited to labour-intensive and labour-based construction methods.
ABOVE Continuously reinforced concrete pavement under construction at Langeni, Eastern Cape BELOW Bryan Perrie, CEO, Cement & Concrete SA
Safety and environment benefits: • excellent light reflection and greater visibility, requiring less energy to illuminate • long-lasting skid resistance and traction for safer driving • no rutting, which could create conditions for aquaplaning • texture can be varied to warn motorists of hazards • uses local materials for construction • can be completely recycled.
account and predicts the degree of likely failure. It also considers life-cycle costs and not just initial costs. This is an important factor when it comes to costing concrete pavements.
How many types of concrete pavements are commonly used?
Should municipalities consider switching to concrete pavements?
There are two main types – the one being in situ concrete and the other concrete block paving. In the case of in situ concrete, there are different design types, with the most common in South Africa being either plain jointed or continuously reinforced. Block paving is generally for lower-volume roads, while continuously reinforced concrete is mainly used for freeways and higher-volume roads. The same situation applies internationally.
Does South Africa have the skills in place to design and build concrete roads? CCSA’s School of Concrete Technology runs a course specifically covering the design and construction of concrete pavements to assist consultants and contractors. In addition, CCSA has a software package – cncPave – for the design of concrete pavements based on South African conditions. The package is comprehensive and innovative. It takes the variability of all the inputs into
Concrete is ideal for low-volume roads and can also be used for overlaying damaged asphalt roads. Concrete roads generally have significantly lower maintenance costs and lend themselves to labour-intensive construction. These are both significant benefits for municipalities.
Do concrete pavements form part of future infrastructural programmes? It is hoped that they will. Sanral is already busy rolling out several tenders for concrete pavements for upgrading and widening the N3 between Pietermaritzburg and Durban, and on the N2 around Durban. From our standpoint, CCSA and its forerunners have always promoted and supported concrete pavement applications. We will continue to promote the advantages so that public and private sector decisionmakers are well informed about the longterm benefits.
