PROS AND CONS OF CONCRETE ROADS
During the commissioning of Dangote Industries in August last year, President Edgar Lungu challenged the Road Development Agency ( RDA) and its engineers to come up with a possibility of constructing concrete roads in Zambia.
The President said, “As you may be aware, my government has traditionally relied more on bitumen for the construction of roads.
This has proved to be not only very expensive but roads have shown that they deteriorate at a faster rate, making it very costly for Government to engage in such projects.
With the reasonable pricing of cement now, we should be able to use more of cement to construct our highways.
This will ensure that the lifespan for our roads can be pushed to over 50 years.
At this point, may I urge the Road Development Agency (RDA) to urgently explore the possibility of putting up roads that are more durable and affordable by utilising more of cement and less of bitumen.I expect a report from RDA in the next three months.
The RDA and the Engineering Institution of Zambia (EIZ) should seriously take up this gauntlet, with the price of cement having drastically reduced as Dangote and Zambezi Portland Cement have played a major role. Apart from doing a cost benefit analysis (CBA) of the two options, i.e. concrete roads vs asphalt roads, we need to also look at the pros and cons of one against the other. Concrete is the most widely used man-made product in the world.
Without going into details of the CBA, the paving cost of concrete roads is a little higher compared to asphalt paving in the sense that it is quicker to do an asphalt (bituminous road) because bitumen has fast setting properties than concrete, which takes 28 days to cure before it can be ready for use.
When you factor in annual maintenance, though, asphalt pavement can cost four to seven times as much money to maintain as compared to concrete, which consequently saves you costs in the long-term on repair and maintenance.
PROS
● Lifespan of 30 to 40 years, whereas asphalt roads last for 10 to 15 years.
● Moreover, concrete roads do not require frequent repair or patch work like asphalt roads.
● Rigid concrete is more durable than asphalt.
● This means that roads paved with concrete are less likely to have potholes compared to bituminous (asphalt) based roads.
● Street lighting is also better with concrete roads than asphalt roads.
● Concrete roads have better resistance to damage caused by automobile fuel spillage and extreme weather.
● Unlike asphalt roads, concrete roads do not get damaged by the leaking oils from the vehicles or by the extreme weather conditions such as excess rain or extreme heat.
● As far as the environment is concerned, asphalt (bitumen) produces lots of highly polluting gases at the time of melting it for paving.
● Likewise, less fuel consumption by a vehicle running on a concrete road means less pollution.
Some of the disadvantages of concrete roads are as mentioned earlier.
CONS
● The cost of paving a concrete road is slightly higher than that of asphalt road.
● Another one is the problem of maintenance.
● In case of defects arising on a concrete road such as cracks, the whole concrete slab may need to be replaced, whereas in the case of asphalt roads, repairing just a part of the asphalt road is easily possible.
● Asphalt roads can be re-layered over the existing layer.
● Asphalt is a recyclable material which can be used again and again by melting it.
● As for safety features, for instance in rainy and the winter season, vehicles tend to slip or slide on concrete roads due to rain and/or snow rain or extreme heat.
● As far as the environment is concerned, asphalt (bitumen) produces lots of highly polluting gases at the time of melting it for paving.
● Likewise, less fuel consumption by a vehicle running on a concrete road means less pollution.
Some of the disadvantages of concrete roads are as mentioned earlier.
We now look up to our engineers at the RDA and EIZ to tell the nation whether the presidential challenge is feasible or not, and if it’s feasible, when can we start implementing the directive on a full scale?
The author is JKL-Associates technical director.