Groundbreaking for the high-profile development property was delayed for three months due to unforeseen circumstances. It was of vital importance to the ownership team to make up for lost time and get the construction back on track for meeting a previously announced grand opening date.
One of the biggest challenges was finding the ideal solution for expediting placement of the elevated post-tensioned concrete floors. The original plan called for concrete with specified strengths of 3,000 psi in 24 hours and 6,000 psi in 28 days. Based on new accelerated construction goals, the project team now needed to push up the 3,000-psi early-strength attainment to 18 hours.
“If the concrete didn’t hit the new 18-hour early-strength target, we would have to wait 24 hours until releasing the post-tensioning tendons,” he said. “This six-hour delay is an eternity when you are working on a demanding fast-track construction schedule.”
- Allen Skogquist, Project Manager, Northland Concrete & Masonry Company
To meet the stringent performance and speed-of-construction requirements for the 18,000-square-foot post-tensioned floor slabs, Holcim developed and supplied 8,500 cubic yards of its next-generation high-early strength concrete technology, called RapidForce®.
The advanced custom-designed RapidForce® mix was rigorously tested in the laboratory and in the field to come up with the highest-quality concrete for delivering rapid high strength and easier workability for the challenging application. Field testing to ensure a high degree of consistency, reliability, and quality control involved placement of a full-size elevated slab deck at the job site that did not require high-early strength attainment for post-tensioning.
“The outstanding performance of the RapidForce® mix made a strong contribution to making up time in the project schedule by saving us a full day of work per week,” said Skogquist. “It allowed us to be very productive the day after the pour, immediately stressing the deck in the morning and then pouring the columns and placing the next deck on top.”
In addition to exceeding the required 18-hour strengths consistently, RapidForce® allowed for easier placement and finishing. “I was really impressed with the workability of the product,” said Chris Glyzinski, the project’s finishing foreman for Northland Concrete & Masonry. “With the RapidForce® mix, I didn’t have nearly as many finishers on the job as I would for a typical difficult to work with early strength concrete, which was a huge benefit in terms of time and labor cost savings.” The hotel opened in August 2020.