POZZOLANS AND BY-PRODUCTS
Cement and Aggregate Substitutes for Regional Belts

Volcanic and Shell Belt
The Pacific Coast region holds vast quantities of naturally occurring volcanic ash from ancient eruptions, in addition to an annual supply of sea shells from the shell fishing industries. Volcanic ash requires no heating to be used as pozzolan and can be mined with greater efficiency than limestone. Over 500 million tons are currently in landfills from the eruption at Mount St. Helens. Over 10 million tons of shellfish shells are sent to landfills annually. Shells can be used as an aggregate up to 70 percent by volume.

Rice and Shell Belt
The Gulf Coast region is the major rice growing region in the country, and supports a significant shell fishing industry. Rice hull ash is a by-product of the rice processing industry that is either burned in the field or goes directly to landfills. When burned at low temperature it is an outstanding pozzolan, extensive material testing has demonstrated that it can replace up to 90% of limestone in addition to being used as biomass to generate electricity. Only 10 percent of seashells in this region are re-used annually, the remainder goes to landfills.

Rust and Coal Belt
The Mid-East region produces 12.4 million tons of blast-furnace slag annually, of which only 3.1 million tons are re-used in other industries. Slag is a non-metallic by-product comprised of silicates, alumina-silicates and calcium-alumina-silicates which can perform either as a pozzolan replacing portland cement by up to 85% of volume, or as an aggregate. Coal-fired power plants in this region produce 55 million tons of fly-ash as a by-product, 46 million tons annually go to landfills. Fly ash can substitute as 50% pozzolan, requires no additional heat processing and reduces the water requirements for making cement by 25%.

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