Air Entrainment in Carbon-Affected Ash

The presence of activated carbon in fly ash can interfere with fresh concrete’s ability to entrain the desired amount of air. As a result, fly ash containing undesirable levels of activated carbon must be treated prior to its sale to ready mix concrete producers.

Eco Material Technologies’ RestoreAir^® process uses a liquid reagent to pre-treat fly ash, before delivery to customers, to neutralize activated carbon’s air entrainment. The technology uses a low dosage of liquid reagent to passivate the carbon surfaces and reduce their ability to adsorb air entrainment agents in concrete. Carbon is not removed, but its effect on air entrainment is neutralized. The technology has been successfully demonstrated on Class C and F ashes containing the most common powdered activated carbons (PACs).

RestoreAir^® systems can be customized to site-specific conditions and constraints. Power plant units with low PAC injection rates and manageable variability can deploy a basic system, whereas swing-load units—those using aggressive PACs—can result in varying ash quality and would require the more robust and advanced features of the RestoreAir^® technology.