The Concrete Quality Control challenge: 
Twins Separated at Birth

We are pleased to invite you to attend a special lunch presentation by ACI President Dr. Kenneth Hover.  This is an event you will not want to miss!  Dr. Hover may be one of the best speakers in the industry.  Here is a glimpse of what you will hear, as only Ken can put it: 

Concrete cylinders and the concrete in the actual structure are like twins separated at birth.  They both have the same parents, they share the same DNA, and if they were both exposed to the same environments and life experiences, they would grow up to be similar in many ways-sometimes even identical in appearance and behavior.  But the concrete cylinders and the concrete structure were separated at birth.  In fact, they were separated at the end of the truck chute.  One was made in layers and placed by hand with a scoop while the other was squeezed, compressed, decompressed, dropped, and splattered into one or many layers.  One was mercilessly beaten and smacked with a steel rod, while the other was shaken with a vibrator (or not).  The rod treatment did not change the air content much, but the vibrator knocked the socks out of the air.  One twin was left more or less alone, all by itself in a cold or hot cruel world for a day or so before it was rewarded by being sent off to a spa where it was pampered and kept warm and moist until its day of reckoning (but the trip to the spa may have been pretty bumpy).  The other twin was at least surrounded initially by more if its own kind (minimizing the effect of ambient conditions), but then it was left for the rest of its adolescence in a more or less uncontrolled environment.  Finally they meet, in the form of cylinder strength vs. core strength, and air content at the chute vs. air content in place.  Is it any wonder that the "twins" are now very different from each other?  Our after-lunch discussion will explore any applications that this story might have on specifying and interpreting standard concrete tests.

About the Speaker

Kenneth C. Hover, P.E., Ph.D. is a Professor of Civil & Environmental Engineering and Stephen Weiss Presidential Fellow at Cornell University in Ithaca, New York, and currently President of the American Concrete Institute.  He is a member of ACI Committees 305 (hot weather), 306 (cold weather), 318A (concrete and construction), past-chair of 308 (curing), and past-chair of 301C (materials and construction).  

Ken is a registered professional engineer in Ohio and New York, and lectures nationally and internationally on concrete materials and construction.  He holds the Outstanding Educator Award from the American Concrete Pavement Association, and from ACI he has earned the Kelly Educator's Award, Philleo Research Award, Structural Research Award, and Arthur Anderson Award.  He also received the ASCE Materials Division's Best Basic Research Paper Award.  The Weiss Presidential Fellowship is Cornell University's highest teaching award, and in January 2006 at World of Concrete he was named one of the "Ten Most Influential People in the Concrete Industry."  Ken has authored or co-authored over 300 technical reports and publications, and presented over 650 technical papers, seminars, and short courses on cement and concrete technology.

"Few people have explained as much about concrete to so many people with as much clarity as Dr. Kenneth Hover...If you've never participated in one of Ken's presentations, you're really missing something."

- Concrete Construction Magazine