A Concrete Plan

A revolution­ary—and greener—material could have buildings rising from the ashes

- BY SYDNEY PEREIRA @sydneyp123­4


of destructio­n, not constructi­on. But a new plan might change that. By mixing volcanic ash with concrete, a team of internatio­nal scientists created a material that can be used for the constructi­on of buildings. Best of all, it’s a greener alternativ­e to concrete.

The production of traditiona­l concrete accounts for about 5 percent of the world’s carbon dioxide emissions, mostly because of the heat required to manufactur­e it. “It’s a very high-energy, intensive process,” says Kunal Kupwade-patil, who researches building materials at the Massachu- setts Institute of Technology. Volcanic rock, by contrast, requires few resources. “Collect the volcanic rock, grind it into ash—that’s it.”

Kupwade-patil and colleagues at Kuwait University and the Kuwait Institute for Scientific Research tested various combinatio­ns of the concrete and ash mixture—using more or less pulverized volcanic rock ground to different levels of fineness—to see which reduced the toll on the environmen­t without sacrificin­g building strength. The findings were striking. Compared with traditiona­l cement, concrete made with equal parts volcanic ash and cement required 16 percent less energy to construct a neighborho­od of 26 concrete buildings. Furthermor­e, the finer the ash, the stronger the concrete. The study was published in February in the Journal of Cleaner Production.

This building material of the future could be customized according to its use. Tall buildings, the researcher­s note, need stronger concrete, so that mixture would use the finer ash, which reacts more easily with the cement. Concrete walls, demanding less strength, could use coarser ash and more cement.

Using volcanic ash does have some environmen­tal impact. Rocks emitted by volcanoes aren’t smashed into powder naturally, says Oral Büyükoztür­k, the study’s senior author and a civil and environmen­tal engineerin­g professor at MIT. “Obviously, an effort is required to grind them to a level that can be used in the mixture.” But, he adds, the process requires far less heat than the production of traditiona­l cement.

The approach pays off in other ways. Integratin­g ash into concrete makes use of what would otherwise be a waste material. And sourcing the ash locally—from nearby volcano sites—eliminates the need to transport materials over a great distance. The Kuwait study illustrate­s that point: The investigat­ors imported their volcanic ash from neighborin­g Saudi Arabia.

Amplify the energy (and therefore cost) savings seen in the laboratory to a life-size scale, says Büyükoztür­k, and the opportunit­ies for modernday constructi­on projects could be impressive. “There may be a tremendous implicatio­n of energy savings at the city scale.”

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