Please join us!
4:30 PM Board Meeting
5:30 PM Registration
6:00 PM Presentation & Dinner
Registration due by Thursday, September 13, 2012.
Coal fly ash means economical, sustainable, value-added concrete construction. Incorporating coal fly ash in concrete improves workability, pump-ability, and finish-ability in fresh concrete, reduces water content and bleeding, and lowers heat of hydration and the risk of thermal cracking. Coal fly ash lowers the water/cementitious-materials ratio leading to lower permeability and increased service life. Fly ash can reduce vulnerability to alkali-silica reaction, reduce the white-staining called “efflorescence,” and can achieve all these benefits to fresh and hardened concrete while consuming a byproduct of electrical power generation and lowering the carbon footprint of cement and concrete. Coal fly ash is a key contributor to the sustainability of concrete.
But including ash in the mixture can modify setting time, which in combination with lowered bleeding rate can modify the window of finish-ability and increase fresh concrete’s susceptibility to plastic shrinkage cracking. Variable amount and form of carbon in the ash can interact with air-entraining admixtures, leading to variable air content whenever ash composition is also variable. The combination of the impact of fly ash on setting, finishing, air entrainment and dependence on good curing means that in the harsh upstate NY environment, the combination of fly ash and care in construction need to be integrated to produce a long-lasting, deicer-scaling-resistant concrete surface. But too much ash, too little care, or a winter than comes too cold or too soon can combine to contribute to an unsatisfactory surface.
For all of its proven benefits as a key ingredient in environmentally responsible and sustainable concrete construction, coal fly ash is at the center of EPA’s hazardous-waste controversy. Initiated by a landfill landslide, questions are arising about the chemical composition of the coal ash, which is derived from, and is as variable as, the composition of the coal itself. Like everything else that is pulled from the earth, the coal that precedes the ash is made of pretty much everything that the planet is made of, and some of those elements are concentrated when the carbon is burned away. But, are the amounts of potentially hazardous elements contributed by the ash any greater than the amounts contributed by other concrete-making and construction materials? And, are any such potentially hazardous materials taken out of the game when encapsulated inside a dense, low-permeability fly-ash concrete?
Ken Hover is Immediate Past-President of the ACI and Professor of Civil & Environmental Engineering at Cornell. He served as a Captain in the 15th Combat Engineer Battalion, U.S. Army, and was Project Engineer and Project Manager for Dugan and Meyers Construction Co. in Cincinnati, working on buildings, interstate bridges, and water treatment plants. Joining THP Ltd in Cincinnati, he became partner and manager engaged in structural design, specifications writing, and contract administration. He holds Bachelors and Masters Degrees in Civil Engineering from University of Cincinnati, and the Ph.D. in Structural Engineering from Cornell University.
Ken teaches reinforced and prestressed concrete design, concrete materials, and construction management. His research focuses on freeze-thaw durability, mixture proportions and ingredients, behavior and testing of fresh concrete, and the impact of construction operations and construction environment on concrete quality.
Ken is a P.E. in Ohio and New York, and holds the Outstanding Educator Award from ACPA, and from ACI he has earned the Kelly, Philleo, Anderson, and Structural Research Awards. He received the ASCE Materials Division Best Basic Research Paper Award. He holds Cornell University’s highest teaching award, and has been named one of the “Ten Most Influential People in the Concrete Industry.”