(Lien en anglais/ link in english) .
Selon IRIN, les termites et la façon dont ils construisent leurs termitières, très solides et résistantes, donne l’idée à la Zambie de tenter un projet pilote. Il s’agirait d’imiter la méthode des termites pour construire des routes plus solides que celles en asphalte mais beaucoup moins coûteuses, espère-ton.
IRIN tells us about who Zambia wants to imitate termites methods of construction in order to build more solid roads but at the fration of the cost of the ones made with asphalt:
LUSAKA, 22 June 2007 (IRIN) – Engineers are mimicking the technology of termites to build cheap, durable, environmentally friendly and desperately needed road infrastructure in Zambia and, in the process, providing jobs at grassroots level.
The almost indestructible nature of termite mounds and the realisation that this technology could be adapted to build roads even more hard wearing than those made from asphalt came at the cost of a broken limb.
“The idea came from my best, best friend, a South African named Henry Halle, who, in his garden, tried to kick those [termite] hills away. On his third try he broke his leg,” said Kim Anderson, a Danish national working in the Zambian capital, Lusaka. “After that he came to me and said, ‘This is something! We need to replicate this technology for construction.’”
Anderson, a regional manager for a Danish air service company, secured financing from the European Union and the Danish government for a road construction pilot project in South Africa, based on termite technology, and a recent initiative in Zambia.
It is not the first time that termite technology has been used to build man-made structures: the Eastgate shopping centre in the Zimbabwean capital, Harare, was modelled on termite mounds, using the design for energy-saving ventilation;
In Europe architectural firms are researching and copying mound technology in the design of high-rise buildings, in an attempt to replicate the termites’ ability to create climate control in their relatively mammoth structures.
“Millions of insects inhabit a single mound. Located in a nest buried approximately a metre beneath the ground, they face a formidable challenge to ventilate the colony and maintain both temperature and moisture constants, whilst protecting the colony from the harsh environment outside, in which they would perish,” said Rupert Soar, a mechanical engineer and researcher at Loughborough University, England, in a recent report.
Though termites are popularly known as wood-devouring pests, 75 percent of the 3,000 known species are classified as soil-feeding, whose diet consists of organic material mixed with clay minerals.
“Environmentally friendly roads differ from asphalt roads: we don’t use diesel fuel to build [them],” Andersen said. “During a visit to South Africa in 1995, we took a look at those big hills made by those small insects. We took a test of the solution they use to mix up the soil, and found we could apply it to clay to make a road.”
Termite mounds have a clay content about 20 percent higher than that of the adjacent soils, reflecting the insects’ preference for smaller clay particles for construction. While being transported in the insects’ mouths or their five gut compartments, the particles are saturated by alkaline and other chemicals, which add nutrients and contribute to the structures’ robustness.
“Soil particles probably undergo modifications in the insect’s gut because of the extremely alkaline pH, reaching values up to 12,” said a study published in the Brazilian periodical, Scientia Agricola.
After duplicating the chemical properties of the ‘cement’ created by termites to harden their mound, which extend one metre into the earth but can rise over two metres above it, Andersen’s team launched their first pilot project in South Africa.
“We found if you mix it with soil, wherever you are in Africa, you can make a very good road, like asphalt. In South Africa we tested it in an agricultural area where heavy trucks are running. Since 1996 to last December , we calculated there have been 11 million vehicles using the road, five million of them heavy trucks, and there has been no wear on the road down to the roadbed. It’s very durable,” Andersen told IRIN.
“The project in Zambia is to make the infrastructure a lot better. When we go out to the villages and compounds, we don’t bring workmen with us. We just bring the material and the few machines we need, and then a week before construction we take local people and train them – show them out to do it. They make their own road, actually. At the same time that we are making an environmentally friendly road, we are also creating jobs,” Andersen said.
“We are going to move out to different countries. Botswana and Malawi are interested, because they have big road problems,” Andersen said. The environmentally friendly termite technology is cheaper than conventional asphalt roads, and more durable.
“We are also funded by different health organisations that need to have the roads done so they can come out to the villages and open new clinics,” he said.
Jack Jones Zulu, manager of economics programmes for the Southern Africa Regional Poverty Network, an NGO working to reduce poverty in the region, said the lack of a road network was felt acutely by small-scale farmers, who were unable to transport their produce to the markets.
He commented that involving local communities in road building projects such as these not only provided jobs, but also sense of ownership of the infrastructure that was not apparent when roads were built by international contractors.
Depending on funding and the productivity of rural village road crews, it was expected that 300km of the new ‘termite roads’ would have been constructed in Zambia by the end of 2007.