High Volume Ash Concrete

High Volume Ash

The purpose of this presentation is to make known an alternative resource in conventional concrete mixtures

Conventional Concrete Extremely versatile Good strength when

reinforced with steel Can be cast to nearly any

desired shape

The manufacturing of Portland cement accounts for 6 to7% of the CO2 that humans produce

What is Fly Ash? A by-product of coal-fired

power plants It uses up space in

landfills

When used in concrete, it displaces more than 25% of the cement

Creates a more stronger bond

Reduces concrete’s environmental impact

Product Comparisons High Volume Fly Ash

Concrete Less energy intensive

manufacture Higher ultimate strength More durable Uses a waste by-product Less global warming gases

created Is a LEED certified material

Conventional Concrete Energy intensive

manufacturing Weaker ultimate strength Less durable Uses virgin material More global warming gases

created

Environmental Considerations

There is no difference in energy performance (as an insulator) in fly ash compared to conventional

The fly ash is less permeable to water, protecting reinforcing steel and adding to the concrete’s durability. Materials that last longer reduce the demand for natural resources and reduce the associated environmental impacts of extracting and processing them.

Cost Considerations

High volume fly ash usually costs the same as conventional

Installation

Improves the workability of concrete because it aids in the placement of concrete into formwork and around reinforcing steel. Consequently, less water is needed in the mix.

Sets more slowly than conventional Concrete

Health Attributes

There are traces of heavy metals in the fly ash. Some debate that the metals are effectively locked

into the cement matrix, preventing their release. By using fly ash in concrete rather than

“landfilling” it, the potential for the metals to leach into the environment is reduced.

Concerns have also been raised about the higher incidence of Radium-226 in fly ash

Alternative Resources

Rice hull ash, created by the controlled burning of an agricultural waste product, can be added to mixes to further increase the strength and reduce the permeability of fly ash concrete.

Works Cited

The Green Resource Center, Berkley, CA www.greenresourcecenter.org