In another few years, local farmers in Uganda will be able to drive their crops – coffee, beans and corn – to markets on a reconstructed feeder road stabilised partly by locally available natural raw materials. Africa's red soil, red clay and volcanic ash are used in the road base of a 40 km long feeder road about 25 km north of the capital, Kampala.
While some of these materials have been used as binder, to date no documented investigations have been carried out and results compared. Africa's red soil will be used as road base on test stretch of road in Uganda. This will now be done with a pioneering project which will culminate in a proposed set of guidelines for the construction of low traffic volume feeder roads in Uganda that extensively utilise local materials.
For the first time, detailed investigations and tests are carried out on a number of non-traditional types of road surfacing that utilise local materials. Strength and durability will be documented by monitoring (road condition registration) test stretches over several years.
The aim is to establish durable roads which can tolerate both traffic load and the torrential tropical rainstorms. In addition, use of these materials can help reduce energy costs and the road maintenance costs. It is estimated that road surfacing costs will be reduced by 30-35 per cent, with further cost benefits accruing through the reduced consumption of imported binder. But the broader perspectives reach far beyond Uganda's borders.
"The project is of great importance not only for Uganda, but also the rest of the world – because this is all about utilising local materials as binder rather than costly imports of asphalt and cement," explains Anders Henrichsen, director with Dansk Beton Teknik.
Initially, a range of stabilisation methods will be tested in a private laboratory in Uganda, with tests performed on five different types of binder to determine their effectiveness in stabilising local materials. The methods will subsequently be tested on stretches of road selected on the basis of uniformity of traffic volume and subgrade conditions.
"Both traffic volume and subgrade strength are important contributory factors in road pavement deterioration," explains COWI project manager Kent Falck-Jensen. "When comparing the durability of different types of road pavement, it is important that traffic and subgrade conditions are uniform for the different test stretches of road. Therefore we have conducted a two-week traffic count as well as relatively comprehensive subgrade investigations and laboratory tests." The aim is that the results from both the design and implementation phases can be incorporated into the university curriculum in Uganda, thereby ensuring that knowledge of these innovative road-surfacing solutions is passed on. By Christina Tækker, cht@cowi.dk Published: 28.06.2004