Welcome to the Annual Concrete Conference! Activities begin at 7:00 a.m. with registration and continental breakfast, followed by a welcome presentation at 7:45 by conference planning committee chair Kevin MacDonald. Session topics include the construction of the Wanda Vista Tower in Chicago, concrete and cold weather, and legal issues. The Concrete Award presentation will take place at 11:45 a.m.
Morning session co-moderators will be Kevin MacDonald, Beton Consulting Engineers, and Mike Hemstad, Short Elliott Hendrickson, Inc. The afternoon session co-moderators will be Rachel Detwiler, Beton Consulting Engineers, and Amy Trygestad, Chase Engineering, LLC.
Enjoy a catered lunch at noon; breaks are scheduled for 9:45 a.m. and 2:30 p.m.
8:00 a.m. Building the Wanda Vista
At almost 1,200 feet tall, Vista Tower will become the third-tallest building in Chicago, and the tallest structure in the world designed by a woman. The 96-story glass-and-concrete tower will house the ultra-luxurious Vista Residences condominiums and the five-star Wanda Vista Hotel. The building’s unique design and dimensions allow for unparalleled views of the city skyline and Lake Michigan.
Sometimes the demands of our industry ask us to do the seemingly impossible. Freeze-resistant concrete, to many, falls under this category. In reality, freeze-resistant concrete is possible and affordable, under the right circumstances. Proper mix design and many successful projects will be discussed.
Shear Design Provisions—A New Approach
The presentation will summarize a multiyear effort that has led to new proposed one-way shear equations for reinforced concrete in ACI 318, Building Code Requirements for Structural Concrete. The equations include size-effect and longitudinal reinforcement terms that are new to ACI 318 shear capacity. The proposed method includes conditions where the existing concrete contribution to shear resistance term (i.e., 2√f’c bw d) can be used.
Legal Issues in Concrete Construction
Like other high-stakes industries, concrete construction invites a fair share of litigation. In this presentation Mr. Coleman, author of Legal Issues in Concrete Construction, will discuss specific construction and legal topics such as cracking, load tickets, substantial performance, the Spearin doctrine, responsibility for mix designs, impossibility of performance, and many more. This presentation will provide interpretations of the courts’ findings and contrast the decisions with other results where possible.
Why Do You Lose Air Volume When Pumping Air-Entrained Concrete and Why Does the Air Come Back?
This presentation summarizes a laboratory and field study that investigated the loss of air while pumping air-entrained concrete. The air was shown to be lost during pumping and then regained over time. This was observed in both the lab and field mixtures by hardened air-void analysis, freeze-thaw testing, and the Super Air Meter. This means that current specifications for testing air-entrained concrete after a pump should be modified.
In 1918, Duff A. Abrams’s Design of Concrete Mixtures was published as Bulletin 1 of the Lewis Institute’s Structural Materials Research Laboratory. Bulletin 1 provided the relationship between strength and water-to-cement ratio, aggregate grading, and aggregate fineness modulus in designing and proportioning concrete mixtures. In 1924, Design and Control of Concrete Mixtures was first published. The 24-page bulletin focused on the mix design method established by Abrams. The 16th edition has grown to 632 pages, including the many advances in concrete technology that have occurred over the past 100 years, and reflects the latest information on standards, specifications, and test methods.
Standard-cured concrete cylinders tell us something about the quality of the concrete delivered to the site. If we want to know about the in-place strength we can match-cure cylinders, but once they’re broken we can’t learn anything more. Maturity helps us monitor and even predict the in-place strength. We can also try out “what if” scenarios in case we want to accelerate the strength gain or minimize cracking. The Silver Ramp at MSP Airport will be used as an illustration of how maturity works in practice.
Zero-lot-line building foundations have been widely used for supporting new structures in close proximity to existing buildings in congested metropolitan areas. This presentation from the American Shotcrete Association will cover design and construction aspects of these walls and highlight how shotcrete placement provides superior strength, flexibility, efficiency, and durability.