Fly Ash
Fly ash has been used successfully as a concrete admixture for decades. Consisting of residue that results from incomplete combustion, typically as a result of coal processing, fly ash is truly a “green” admixture that makes use of a material that would normally be considered waste.
Fly ash can be directly substituted for the cement in a concrete mix in percentages ranging from approximately 20 to 35 percent (by weight). Aside from the reduction in environmental impact, fly ash also provides benefits during the construction process and in the finished concrete product. Generally, mixes with fly ash have improved workability and require less water to maintain a given strength requirement. The cured concrete provides enhanced resistance to corrosion of the internal steel reinforcement and also helps provide a barrier against sulfate intrusion in cases where the concrete is cast directly against soil.