Concrete roads an alternative to tar

Concrete – as opposed to tar – is the ideal medium for building roads and pavements in developing countries, according to Bryan Perrie, author of a technical manual for the design, specification and construction of low volume concrete roads and pavements.
The manual has been published by the Cement and Concrete Institute of South Africa whi Concrete – as opposed to tar – is the ideal medium for building roads and pavements in developing countries, according to Bryan Perrie, author of a technical manual for the design, specification and construction of low volume concrete roads and pavements.
The manual has been published by the Cement and Concrete Institute of South Africa which is actively promoting the use of concrete for road construction It is written for consultants, municipal engineers and contractors.
Perrie says concrete is the answer for developing countries as the raw materials – sand, stone, water and cement – are locally available.
Another benefit is that it is labour intensive,creating employment and opportunities for labourers to learn skills. These skills, he states, are transferable to other trades, whereas training in bitumen has limited applications. This is a great inducement for government agencies to consider concrete as an alternative to tar.
As the use of machinery is not essential, a major financial outlay is not required. Tar roads require spray tankers, which are costly. It is, however, possible to construct concrete roads mechanically, which may be more applicable for first world countries. Both methods are covered in the handbook.
A further advantage in the use of concrete is its strength and durability. Concrete is oil, chemical and weather resistant. This strength actually increases with age. These roads have an estimated service life of 40 years.
In comparison, tar roads are not weather resistant and potholes are commonplace. Financially the maintenance costs associated with concrete roads are far less than for tar. Another financial advantage is that, due to the excellent light reflection on concrete roads, lighting costs are reduced.
In terms of safety this light reflection is advantageous, concrete roads are also skid resistant and have improved traction. They may be grooved for improved run off. Concrete roads may be dish shaped and thus serve the dual purpose of water drain as well as road. This keeps the costs down. Concrete is also suitable for steep roads.
The disadvantage of using concrete is that it is only suitable for low volume roads with traffic of less than 1,000 vehicles per day, and of which only 30% are commercial vehicles, with a maximum weight of eight tons on a single axle or 14.5t on a tandem axle. This may be problematic in urban areas.
The manual is published by C&CI and is available for $15.

C&CI: bryan@cnci.org.za Tel +27 11 3150300 Fax +27 11-3150584
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