C+S January 2020 Vol. 6 Issue 1 (web)

Construction required an advanced SCC solution to flow through and consolidate around highly congested reinforcement in the columns without the use of vibrators. Photo: New Orleans International Airport

One of the biggest challenges in constructing the tall and complex columns was finding the ideal concrete mix that would perform on a variety of levels. The use of a conventional concrete was not an option for this application due to all the highly congested steel reinforcement, embeds and anchor bolts within the columns. In addition, project specifications required a high-quality class A exposed concrete finish, which would not be possible using a standard concrete mix. According to Mike Lopez, project superintendent at Gibbs Construc- tion, the project team needed an innovative concrete solution that would flow easily through and firmly self-consolidate around all the highly congested embedded reinforcement within the columns, as well as achieve a 28-day compressive strength of 7,000 psi. The concrete also needed to produce a smooth high-end surface aesthetic that the owner was expecting with every pour. Selecting the right mix To meet the stringent performance criteria for this high-vertical ap- plication, the project team selected an advanced self-consolidating concrete (SCC), called Agileflow™ (formerly Agilia®). This highly fluid concrete places more quickly than standard concrete, flows easily through highly congested reinforcement and provides superior non- segregation properties for greater structural integrity. Other advantages of the SCC technology include increased strength, higher-quality fin- ished surfaces and reduced production times and labor costs. “We used this very workable SCC mix provided by Lafarge on another project that had very large transfer beams containing highly congested steel rebar and post-tensioned cables,” said Lopez. “Based on the prod- uct’s performance in that extremely challenging application, we were confident that it was the ideal solution for constructing the structural support columns at the airport.” Based on all the logistics challenges and other delays that come with working on a 100-acre airport construction site, the ability of the product to maintain its workability for up to two hours was another

benefit valued by the project team. With most standard SCC mixes, the spread starts to decline tremendously at 1 hour and could cause

stability problems. Custom solution

Following a common defined procedure, Agileflow mixes are custom- designed based on the targeted performance properties for each site- specific application. The key to successful performance requires special care in the selection and proper proportioning of materials in the mix to avoid segregation while providing optimal workability properties. Primary considerations in developing the optimal concrete for the airport columns were flowability, viscosity, compressive strength, durability and maximum temperature gain control. Key performance parameters included compressive strength of 7,000 psi at 28 days, maximum temperature of 95 degrees F, and spread of 28 to 31 inches. “We design our Agileflow advanced SCC mixes to flow at higher ca- pacities and to avoid separation in applications with high drop heights,” said BJ Eckholdt, quality control manager at Lafarge, a member of LafargeHolcim. “With the concrete developed for the airport columns,

The Agileflow SCC product allowed for a high-quality smooth painted finish on the columns. Photo: New Orleans International Airport


january 2020


Made with FlippingBook Annual report