Ancient Technology Used To Stabilize Roads in Ethiopia

Ancient Technology Used To Stabilize Roads in Ethiopia

An Israeli-Canadian company that makes soil-stabilization products has make commercial inroads in Ethiopia’s capital, where soil swells when it rains and shrinks when it’s dry, causing roads and buildings to buckle, according to a report in Haaretz.

Fissures and cracks kept appearing in Addis Ababa’s soil, the report said. Municipal and government leaders brought in foreign engineers for advice. The solution, the professionals determined, was to remove the layer of soil that lay between 70 centimeters and 1 meter below the surface, and to fill in that space with other materials. Only that way would it be possible to stabilize the ground and pave a road that would remain intact.

Except that fixing each kilometer of road that way would require about six months of work.

AnyWay Solid Environmental Solutions makes powder containing a mixture of cement, lime, plaster, steel slag and polypropylene fibers. It is inserted into the ground, stabilizing it by altering its mechanical engineering qualities, the report said.

With the help of the Addis Ababa municipal roads authority, AnyWay drew up an engineering plan and proceeded to change the properties of the top 20 centimeters of soil.

“It was possible to begin repaving the road immediately,” with that method, says Zeev Halber, CEO of AnyWay Israel. “The paving time could be shortened from six months per kilometer to just four to six weeks.”

AnyWay’s product is based on technology developed by the South African arms industry during the apartheid years, the report said.

AnyWay did not invent the idea of stabilizing soil by means of steel slag. This technology has been around for thousands of years. The Roman Empire used it extensively. The Romans knew that steel slag − a byproduct of smelting, cooling and grinding − develops cement-like characteristics over time when combined with calcium and water.

This trait, called “pozzolanicity” is what allows soil stabilization to continue and even grow stronger over a long period, which explains the durability of Roman roads over 2,000 years.

The technology improved the properties of the natural soil instead of replacing it with filler materials, saved about 40 percent of paving costs, lowered the cost of maintaining the road long-term, and also cut carbon dioxide emissions resulting from the work by 40 percent compared to using the filler method, the report said.

AnyWay also prepared the infrastructure for paving, which was done entirely in cobblestone, under the guidance of GTZ, a German state-run enterprise for technical co-operation, and with funding from World Bank.

The project created jobs for thousands of people who were subcontracted to quarry the stones and do the paving,