Professional Engineers Of North Carolina

SUM 2014

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6 the Professional Engineer Summer 2014 M y frst hands-on work with coal fy ash was as a graduate student. I was evaluating its potential as an adsorbent, removing trace metals from groundwater at contaminated sites. Te contaminant concentra- tion levels I tested were considered hazardous — orders of magnitude higher than the levels in CFA. CFA was attractive for many reasons, but in this application its reasonably small particle size and large unit surface area were important. More surface means more opportunity for adsorption. Te notion that CFA would come to be alleged hazardous was not in the collective engineering consciousness at the time. And notwithstanding the many news articles that described CFA as "toxic sludge," the material remains nonhazardous and useful — if managed properly. CFA is useful as a construction material and additive that increases a soil's stability. If you want high-strength, longer-lasting concrete that cures without excessive heat then use CFA. Use it not as a fller and not to minimize a waste byproduct but because of its desirable properties. Concrete is the No. 1 re-use application of CFA and will likely continue for years to come. CFA also can be used to make geopolymer cement, a Portland cement alternative that is being used in more applications. Under the direction of Dr. Brett Tempest, geopolymer cement was used in Lose it by using it A plan for coal fy ash from the 33 ponds throughout North Carolina F E AT U R E S T O R Y B y D r . J o h n L . D a n i e L s , P e Coal ash pond sites in North Carolina

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