The outside facade of the Billy Earl Dade Middle School in Dallas, Texas, which opened on time and under budget thanks in part to a new rapid-drying concrete technology.
The relative humidity in the concrete slab was under 80% within 21 days, allowing the contractor on the project to install floor coverings, like the carpet in the auditorium, well under the 4- to 8-month wait period typical with regular concrete floors.
Satterfield & Pontikes installed a variety of floor coverings throughout the 150,000 square feet of Aridus concrete floors, including VCT tile, ceramic tile, porcelain tile and carpet.
There is little difference in the placing and finishing process with Aridus, except for the requirement that absolutely no new water can be introduced to the mix. Finishers are required to use a proprietary solution to clean and wet tools.
The new Billy Earl Dade Middle School in Dallas, Texas, welcomed students on time and under budget, thanks in part to a new rapid-drying concrete technology that allowed contractors to install floor coverings after only 21 days. The construction team of general contractor Satterfield & Pontikes Construction, Inc., architect KAI Texas, concrete supplier Redi-Mix Concrete, and the Dallas Independent School District selected U.S. Concrete’s Aridus Rapid Drying Concrete to shorten the construction schedule 30%, from 14 months to 10 months. The move also resulted in similar reductions in construction overhead costs.
Aridus Rapid Drying Concrete was developed and patented by U.S. Concrete’s National Research Laboratory, USC Technologies, Inc., to address recent changes in environmental government regulations that limit or restrict VOCs in flooring adhesives. While these new formulations may reduce the environmental impact of new flooring installations, the new adhesives are less durable and more susceptible to moisture-related issues. In response, contractors have combated the problems by adding sealers or lengthening the drying time of the concrete, in hopes of reducing the risk of liabilities associated with the failures of floor coverings. In addition, these remedies increase the construction time and costs associated with the projects.
Aridus Rapid Drying Concrete consumes the excess water and accelerates the drying time. At the Billy Earl Dade project, Jim Hagemann, senior project manager with Satterfield & Pontikes, says the floors showed relative humidity readings under 80% within 21 days — a much shorter timeframe than the usual 4- to 8-month wait time for those readings with a typical concrete mix. That allowed contractors to install the various floor coverings, including VCT, carpet, ceramic tile and porcelain tile, throughout the floors in the school on a much earlier timeframe. It also allowed them to avoid installation of a moisture mitigation system, which can cost anywhere between $1 and $6 per square foot.
Placing and finishing
Satterfield & Pontikes placed approximately 8,500 cubic yards of Aridus at the Billy Early Dade school project for nearly 150,000 square feet of floors over three elevated decks.
Hagemann says there was little difference in the placing and finishing of Aridus than any other 5,000 psi concrete mix. It pumped easily and it finished well, and crews were able to get the trowels on the slab a little quicker.
“The key to success with Aridus is based on the limited water in the mix — you cannot use any extra water whatsoever during placing and finishing,” he explains. Instead, the pump operator and finishing crews used a proprietary product supplied by U.S. Concrete to clean and wet tools, use as a finishing aid, and prime the pump.
The Aridus slabs reached full strength within 48 to 72 hours, allowing crews to strip formwork and remove shoring on an accelerated schedule. The low water-to-cement ratio in the mix also contributes to minimizing slab curl and warping issues.
Hagemann says Aridus is an “industry changer.” Satterfield & Pontikes is already planning its use on future projects because of its ability to cut construction schedules and costs while offering a solution to the floor covering issues that have plagued concrete contractors for years.