Unexpected problems can lead to innovative solutions when jobs don’t run smoothly the first time around.

Just ask Ben Olson of R. Olson Concrete Contractors, who worked with general contractor Enger-Vavra, Inc. to restore nearly 200,000 square feet of factory floor for leading engine manufacturer Navistar.

The challenge: to create new floors in vast sections of Navistar’s existing plant in Melrose Park, Illinois, working around crews refinishing ceilings and walls in the same space.

“After the old flooring had been removed, we scarified the concrete subflooring to create a bondable surface and remove substances that had seeped in over the years,” Olson says.

Navistar engineers favored a 2-step process for creating the new surface, he notes. “This involved laying down 2 inches of concrete topping, then using spreaders to distribute trap rock over the surface.”

Test pour uncovers the issues

R. Olson crews did a 10,000-square-foot placement to test bonding and other critical requirements. The results shocked just about everyone involved with the job.

“Within two weeks, we saw dramatic cracking and curling,” says Olson. “The concrete and bonding agent just failed.”

Thinking the trap rock was drawing too much moisture from the relatively thin concrete layer, Olson suggested moving to an integral trap rock mix paired with a true epoxy bonding agent.

With Enger-Vavra’s project manager, Bill Tyler, in agreement, Olson reached out to Prairie Material to explore fresh ideas.

A P2P solution

Prairie’s Technical Services Team recommended a new mix with integral trap rock plus macrofibers to add strength and minimize cracking. The formula also incorporated a shrinkage reducer and water reducer.

The new approach would transform 2 steps into 1, reducing labor while addressing the curling, cracking and debonding seen earlier.

In partnership with Olson, Prairie experts and engineer ​Larry Kaiser from W. R. Grace presented the solution to the construction team. Navistar engineers approved a new test section.​

This time, the mix achieved a “pure chemical bond, curing from the bottom up, which was exactly the result we wanted,” says Olson. “The test sections took serious abuse from the ceiling and wall renovations going on all around them, but they held up perfectly.”

Following mix adjustments to reduce set time and approval of final tests, crews quickly completed the pours, first in an 85,000-square-foot section of the plant and later, in a 102,000-square-foot area.

Continuous on-site support provided by Praire’s Technical Services Team helped the job conclude smoothly. Navistar should see years of strong performance from the finished floors, Olson says.