Prescription for Performance
- Written by CP Staff
The St. Louis Art Museum East Building is McCarthy Building Companies’ largest SCC application on a building contract since its crews began placing the material in 2000. Details on the concrete methods throughout the contract were added to McCarthy KnowledgeBuilder, a company-wide online reference source of best practices, idea sharing and trouble-shooting.
“We had very seasoned concrete supervisors and carpenters, some with more than 20 years of experience in formwork and challenging pours. The goal was consistency in finish and color, top to bottom, and along the base of the coffers. Breckenridge saved the day with a delivery and production process to meet the quality expectations, as high as they were,” says Knoebel. “Every time we have a signature concrete project, we learn a lot about the properties of special materials like self-consolidating mixes, along with the planning and execution skills required for success. The technology of self-consolidating concrete has come a long way. The levels of quality we attained at the museum expansion give us greater confidence to recommend SCC on appropriate jobs where conventional mixes are specified.”
McCarthy and Breckenridge Material staff developed the museum’s SCC design over a July 2010–April 2011 window, testing dozens of Peri board mockups and mixtures for finish quality. During the preparation phase, the contractor also gauged mixes’ maximum travel or flow distance at 100 ft., configuring the ceiling pours so that the pump hose could remain stationary or be moved once or twice only. The pours spanned beams contained in up to 3,500 sq. ft. of horizontal deck area.
Mindful of the mix performance and finished surface quality parameters, Jeff Whidden and his technical staff finalized an SCC mix design using Grace Adva 140M and Adva Cast 575 mid range and high range water reducers, respectively; a Buzzi-Unicem Type I/II portland cement supplemented with slag and fly ash; grades of fine and coarse aggregates from local sources; and, a Davis titanium dioxide pigment netting color and brightness characteristics aiding in the achievement of the light reflectance target.
“The St. Louis Art Musuem expansion is our best example of product quality and technical leadership. We aim to be the market’s biggest and the best ready mixed producer,” notes Whidden. “We know what it costs to have a technical staff. Contractors find that low price will not support the expertise and level of quality they are looking for from a concrete supplier.”
Whidden joined Breckenridge Material shortly after the MoDOT lab certification and has doubled the technical staff since. He arrived in St. Louis from Los Angeles, where he had served as vice president of Sales and Technical Services for iCrete LLC. Prior to the mix design and materials optimization specialist, he was vice president of Sales & Marketing, North America, and subsequently general manager of New Mexico operations for Lafarge.
At Breckenridge Material, he has sought to brand and customize concrete, and assure designers that a ready mixed producer with scale and technical resources belongs at the project table early on—equipped to offer something beyond a standard mix pulled from a library. The St. Louis Art Museum East Building, which required 1,600 yd. of the premium SCC mixes, plus 20,000 yd. of more standard column and slab mixes, is sure to instill confidence in prospects open to Breckenridge Material’s case for performance versus prescriptive specifications.
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