Concrete Products covers the issues that attract producers of ready mixed and manufactured concrete focusing on equipment and material technology, market development and management topics.
Issue link: http://concrete.epubxp.com/i/442865
66 • January 2015 www.concreteproducts.com One of the more ambitious technologies in the long history of the Master Builders Solutions brand is on track for a commercial launch in the second half of 2015. After the 2014 Con- Expo-Con/Agg preview of a polymeric, micro- sphere-based agent manufactured at the batch plant and aimed at replacing air-entraining agents, BASF Construction Chemicals' Admix- ture Systems commenced market awareness and acceptance activities. Formally branded MasterSphere FT 300, the technology positions producers and their cus- tomers to improve slabs and structures' freeze- thaw durability, and overcome void size and distribution variability challenges traditional- ly associated with air-entrained concrete mix- es. That variability is especially owed to the effects on air voids of aggregate, cement and supplementary cementitious materials; air-en- training agent dosage; batch contaminants; mixing dynamics; temperatures during batch- to-placing window; and, mix slump changes. MasterSphere FT 300 is dosed at 1 percent by volume of concrete, equating to upwards of 500 million microspheres per cubic yard, versus the 22 million air voids conventional air-en- training agents impart in the same quantity. BASF Admixture Systems' on-site production process yields uniformly sized microspheres, primarily less than 100 microns in diameter. Low specified dosage rate for MasterSphere FT 300 enables producers to proportion new mix designs of optimized cement content, according to product developers. Using con- ventional air-entraining agents to achieve 5 percent to 8 percent air content, producers need to increase and tailor cementitious mate- rial content to meet compressive strength tar- gets. By eliminating the need for air-entrained concrete and establishing a 1 percent Master- Sphere FT 300 target volume, the new system invites fine and coarse aggregate optimization at the expense of higher cost binder. "Up until now, air entrainment has been the state-of-the-art technology for freeze-thaw durability," says Juan Alfonso Garcia, vice president, BASF Admixture Systems/North America. "But concrete professionals deserve a technology that is more stable and predictable no matter what the environmental conditions may be. Our global team has spent seven years developing this game-changing technology to give customers more control so they can dose their concrete and be done with it." FEATURE BY DON MARSH Besting Bubbles BASF set to master conventional air-entraining alternative Admixture Systems Manager, Product Management Tony Schlagbaum (left) and Product Manager Mark Bury open an Illinois Department of Transportation demonstration of the air-entraining alternative and production prototype. The event was staged at the agency's Bloomington Maintenance Facility, nestled at the Interstate 55 & Interstate 70 junction, and drew 50 state, county and municipal engineers, including Chicago Department of Transportation staff (opposite page). "Microspheres are manufactured at the producer's plant to provide consis- tent, stable performance, every time," adds BASF Admixture Systems Tech- nology Manager Paul Seiler. "They are dispensed and uniformly mixed into concrete at a fixed dosage and are the optimal size for freeze-thaw durability." The hollow MasterSphere FT 300 spheres have highly resilient, tough, but flexible, polymeric shells. Similar to entrained air, they provide stress relief zones for the expansion of freez- ing water within concrete, imparting long-term durability. The compressive strength of concrete treated with the microsphere-based admixture technol- ogy can be over 30 percent higher than an air-entrained concrete due to net air content difference. Continued on page 68