Use of Class F Fly Ash as a Supplemental Binder in Foundry Mold Production

摘要

Bentonite clay is extensively used as a foundry sand binder. Foundry operating costs could be reduced if a less expensive binder is used either as a replacement or supplement to bentonite. For example, fly-ash (a byproduct of most power plants) is locally and readily available at a lower cost than bentonite. From this project, it was determined that the addition of fly-ash based binder (composed of class F fly-ash plus calcium hydroxide and accelerator) to the foundry sand mixture of sand plus bentonite had improved green compressive and green shear strengths of the sand mixture compared to sand bonded with bentonite alone. Results showed that when the bentonite dosage was 3.5 percent, the green shear strength increased by 17 percent when 3.0 percent fly-ash based binder was added while the green compressive strength increased by 75 percent. At 1.5 percent bentonite dosage the green compressive strength increased by 168 percent when 5.0 percent fly-ash based binder was added.