Coal Byproducts – Fly Ash Cement

This is Part 2 in a Multi-Part Series Examining the Uses for Coal Byproducts.

ALLIANCE – When thinking of the burning of coal for the production of electricity, one may think of the plants used during the industrial revolution. During that period in history little to no filtration was used, which accounted for the black smoke pouring from the tops of the smoke stacks.

Now, a series of filtration systems scrub the contaminants from the air before releasing it into the atmosphere. The white “smoke” seen coming out of the smokestacks is virtually nothing but water vapor and carbon dioxide.

Of the byproducts of the burning of coal for electricity, fly ash is essentially the ash that rises as pulverized coal is burned in a boiler. Filtration systems catch this fly ash and prevent it from entering the atmosphere.

The Environmental Protection Agency describes fly ash a very fine, powdery material composed mostly of silica made from the burning of finely ground coal in a boiler.

Just as with a multitude of byproducts from the burning of coal for electricity, fly ash has practical applications that can benefit certain industries.

Cement is the primary component of concrete and is produced in the level of millions of tons a year. The process of producing one ton of cement creates one ton of carbon dioxide. By adding fly ash to the cement mix, the amount of carbon dioxide from producing cement can be significantly lowered.

Fly ash was used at levels of up to 30% in cement, but can comprise up to 50 to 60 percent and provide a range of benefits. By adding the fly ash, the amount of carbon dioxide the cement produces lowers respectively.

Fly ash cement has benefits beyond simply lowering the amount of carbon dioxide produced.

Fly ash cement is cheaper than the more commonly used than the favored Portland cement. It is known to improve workability and reduce internal temperatures as the cement sets, a report from the Tennessee Technological University states.

TTU explains fly ash improves workability as a result of the “ball bearing” action of the spherical fly ash particles. Fly ash improves the grading in the mixture by smoothing out the fine particle distribution, and it is known to reduce the amount of water required by 15 to 20 percent.

The Proceedings of the International Workshop on Sustainable Development and Concrete Technology, in a 370 page report explains “From theoretical considerations and practical experience the authors determined that, with 50 percent or more cement replaced by fly as, as it is possible to produce sustainable, high performance concrete mixtures that show high workability, high ultimate strength and high durability.”

The report delves into specifics such as tensile strength, support strength, lifespan and more.

While the entire amounts of coal-burning byproducts are not fully utilized, industries continue to find ways to utilize the would-be pollutants for practical use in a multitude of applications.

 

Source References Available upon Request.