Tech Talk Tuesday - The Concrete Quality Control Challenge: Twins Separated at Birth

You are invited to the second meeting of the new Minnesota Concrete Council ACI Chapter that will be held Tuesday, May 21 at Midland Hills Country Club in Roseville.  The presenter will be Ken Hover, Ph.D., P.E. (Cornell University).

The Concrete Quality Control Challenge: Twins Separated at Birth

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—perhaps 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 with no more than a 12-inch drop, while the other was compressed, decompressed, pushed around 90-degree pipeline elbows, and dropped for up to 4 feet. One was mercilessly poked and prodded with a steel rod, while the other was shaken with a vibrator (or not). While the rod treatment can increase apparent air content, the vibrator always knocks 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 left for its prime developmental stages 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?

This presentation will explore any applications that this story might have on specifying and interpreting standard concrete tests.

Attendees will be emailed a certificate of attendance for one professional development hour (PDH) at the conclusion of the event.

Cost to attend this event is $35 after May 14 or $25 early-bird before May 14.


May 21, 2019 at 11:30 am


Midland Hills Country Club
2001 Fulham Street
Roseville, MN 55113


Cost to attend is $35 ($25 early bird) and includes a hot buffet lunch, applicable credits and handouts.


Attendees will receive a certificate of attendance for one professional development hour. Please be sure to check in at the registration desk to receive your credit.