Turning trash into cash

SYDNEY, Australia-Slag heaps are mountainous eyesores of waste found on the fringes of steel mills. But Australian engineers say they have found a way to turn trash to treasure by recycling more of this byproduct into highways.

Slag is currently used worldwide in buildings and roads for cement blending and improving the life expectancy of concrete structures. But, explains Vute Sirivivatnanon, head of the sustainable materials engineering unit research team at the Australian Commonwealth Scientific and Industrial Research Organization (ASCIRO), "that is blast furnace slag resulting from production using mined raw material."

His group's research involves another type: electric arc furnace slag, a byproduct of the process in which scrap metal is used rather than the output of mines. And after a year of testing, ACSIRO business development manager Robert Baker is confident that this form of slag promises a number of commercially viable options.

Among them are anti-skid surfaces for paved highways. The highways department in Victoria tested slag from the mill and found that it provides an excellent skid-resistant material for roads. The researchers believe it will be popular for stretches along curves or near dangerous intersections. Other uses include blending it into asphalt or concrete for different types of road surfaces and as an inexpensive additive instead of stone and sand to low-strength concrete for sidewalks and bicycle paths.

"We've found a way to turn something ugly that just sat there into a useful and profitable product," Sirirvivatnanon said.