Recycled glass gives concrete more muscle

MICHIGAN STATE (US) — Mixing ground waste glass into cement makes the resulting concrete stronger, more durable, and more resistant to water.

In addition, this use of glass helps reduce the amount of glass that ends up in landfills and helps to reduce carbon dioxide emissions, which are common due to the high temperatures needed to create cement.

The concrete, in which about 20 percent of the cement that is used to produce the concrete is replaced by milled, or finely ground, glass, is being tested at a number of sites on the Michigan State University campus. And, so far, the results have been positive.

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“Milled glass enters a beneficial reaction with cement hydrates, so basically the chemistry of the cement improves with the glass,” says Parviz Soroushian, a professor of civil and environmental engineering who has been studying the glass-concrete mix. Soroushian and colleagues report their findings in the journal Construction and Building Materials.

“It makes it stronger and more durable and doesn’t absorb water as fast as regular cement.”

The test sites, which have been in existence for about three years, are located on sidewalks outside of the MSU Surplus Store and Recycling Center, on the east side of the campus.

“It’s satisfying to see research done in MSU laboratories have very beneficial applications right here on our campus,” says Lynda Boomer, energy and environmental engineer with the MSU Physical Plant.

The concrete doesn’t look too much different than standard concrete, Boomer says. “It’s a little lighter in color, but, for the most part, pretty indistinguishable.”

“Cement is processed at a very high temperature,” Soroushian says. “Using milled glass significantly reduces the amount of energy used, as well as CO2 emissions.”

“We anticipate that this novel practice of partially replacing cement in concrete with mixed-color waste glass, which is based on sound chemical principles and the pioneering laboratory work conducted at MSU, will yield significant environmental, energy and cost benefits,” says Roz Ud-Din Nassar, a doctoral student in civil and environmental engineering who also worked on the project.

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