New Admixture Will Eliminate Need for Air-Entrained Concrete
After seven years of development, the BASF Corp. is getting ready to introduce a liquid admixture that will take the place of air-entrained concrete in areas affected by freeze-thaw cycles.
An article in the Engineering News-Record said the admixture, which BASF plans to introduce next year, contains millions of tiny spheres that have been coated with a tough, flexible polymeric shell, “similar to very tiny tennis balls.”
The spheres help cushion the forces generated by freeze-thaw cycles, making the concrete more durable. That’s exactly what air-entrainment is designed to do, but the tiny air bubbles are easily popped. BASF adds that air-entrainment also weakens concrete between 3% and 5% for every 1% of air that’s added.
Air-entrained concrete typically contains between 4% and 7% air, ENR said. Concrete made with the new admixture would be about 30% stronger.
Dry microspheres have been on the market for decades, the article said, but they’re prone to handling problems and high delivery costs. They’re also difficult to manage because they’re so light. In contrast, the BASF admixture will be shipped as a slurry.
BASF is planning experimental road projects in Minnesota, Virginia, and Ohio before next year’s commercial launch.