Miracon Technologies, Inc. cites a new system for highly stable air entrainment in concrete. According to the technology developers, it yields air with near-optimal bubble size and spacing little affected by carbon in the mix, high-alkalinity cement, other admixtures, extended mixing times, pumping of the concrete, temperature, water added to the mix, or other factors that commonly push air volumes beyond specified limits. Compared to conventional air entrainment, company engineers affirm, Miracon's chemistry and bubble structure produce less reduction in concrete strength; potentially lower cement dosages can translate to materials savings of roughly $0.50-$2.00 per yard for standard concrete applications.

The system includes a new admixture and dedicated machine to aerate it. In contrast to conventional air-entraining admixtures (AEAs), which are surfactant-based, Miracon's admixture is polymer based. The specially engineered aeration machine is said to produce precise and stable bubbles, injected into the truck or mixer as the last ingredient of the mix. One Miracon machine has sufficient capacity to serve even large ready mixed plants; and, return on investment due to materials cost savings can be expected in less than five months, the company notes.

Several ready mixed producers nationwide have implemented the system to maintain stable air entrainment with the use of fly ash and high or variable carbon levels. In precast and manufactured stone plants as well, it reportedly can produce lightweight concrete of relatively high strength, allowing precasters to replace lightweight aggregates with Miracon in mixes of 2.0-8.0 percent air for significant cost savings. For the same reason, the technology firm asserts, some producers recently have begun using Miracon for lightweight structural mixes. — www.miracontech.com