Prof Hubert Rahier’s team at the Flemish Free University of Brussels, the VUB, has developed a new technique to recycle old concrete nearly completely. The technology will be used in Ukraine from the end of the year onwards in order to rebuild houses and other buildings using the same materials.
Prof Rahier worked with several Dutch and Belgian companies to develop the technique. Using a smart crusher and a large powerful microwave oven the various components are separated and then used to make new concrete.
“Concrete consists of stones, sand and cement. The most difficult part is separating the cement from the sand. By rubbing everything over each other and by not crushing the concrete into small pieces , everything can be easily separated” explains Prof Rahier.
After their treatment in the smart crusher stones and sand can be used again straight away. It’s different for the cement: “It’s not easy to recycle used cement” says Rahier. “We needed an extra step to recuperate as much as possible. We heat the cement to high temperatures of 500 to 600°C in the microwave. Then it can once again be used as a binding agent”.
A Ukrainian company Sheldor heard about the technique and contacted the professor: “We are a host family for a Ukrainian family and that helped in our contacts with the firm”.
Prof Rahier says a number of teething problems with the machinery remain, but he is confident they can be sorted.
The new procedure should help to reduce CO2 emissions linked to concrete production drastically: no truck is needed to take the raw materials to the factory.
“Machines can be installed in the street as long as there is power. They could be modified to run on an alternative power source but we’d like to keep it as environmentally-friendly as possible. Concrete produced in this way is cheaper than conventional production. Our technique can also be used in disaster areas e.g. the parts of Turkey and Syria hit by the recent quakes”.