Award-winning contractor and portland cement producer Vinton Construction Co., Two Rivers, Wis., continually seeks new and innovative solutions. The company had used rapid-hardening Rapid Set® calcium sulfoaluminate (CSA) cement-based concrete repair products here and there, but not in large quantities.
That changed when Vinton was awarded a contract by Outagamie County in Wisconsin for work at the Appleton International Airport (formerly Outagamie County Regional Airport).
Opened in 1965, the airport’s two portland cement concrete runways intersect rather than run parallel to each other. Therefore, when pavement in the 150-foot-by-150-foot intersection needs repair, operators must suspend all air traffic until repair material has cured. The contract required 725 linear feet (LF) of partial-depth joint repair, 417 LF of partial-depth edge repair, and 124 square feet of partial-depth surface repair to reach 3,100 psi compressive strength by 6 am every day for eight days. Failure to do so would result in fines of $2,500 per 15-minute interval until 7 am; $2,500 per 15-minute interval from 7 am to 8 am; and $2,500 per 1-minute interval after 8 am until the airport reopened.
The airport would close at 8 pm each night. “It’s pretty tight,” says Westwood Infrastructure Project Engineer Ben Backus, who worked on the project. “By the time you saw, remove, and prep, it’s getting to be 11 pm, midnight before you can start to pour concrete. And then there’s cure time.”
Given the timeline and potential damages, says Vinton’s Heath Schopf, P.E., the company’s bid relied on using Rapid Set® DOT Repair Mix. The mix is a blend of Rapid Set® CSA cement, plasticizer and air-entrainment additives, and ASTM C33 concrete sand that reaches 5,000 psi compressive strength in three hours. When extended with pea gravel, it reaches 4,200 psi in three hours.
“We do a lot of partial-depth repairs on runways with standard Type IL cements, but we couldn’t have reached that opening strength with portland cement concrete,” says Schopf, who was jobsite construction manager. “In addition to prepping, placing, and curing, we had to make sure there was enough time for sweeping before 6 am. With its exceptional early strength, DOT Repair Mix met our time frames.”
Beating the Heat on the Jobsite
Vinton has several portland cement plants throughout Wisconsin, and its fleet includes ready-mix trucks and a portable batch plant in addition to mobile mixers. This was the crew’s first experience placing more than a couple bags of a Rapid Set® product at a time. Mixing, placing, and finishing is virtually identical to portland cement, but equipment and material should be fully staged and ready to go to ensure successful placement within the material’s 10-to-25-minute working time.
To ensure repairs ran like clockwork, the crew first used DOT Repair Mix to rehabilitate taxilane damage. Because August nights in Wisconsin are hot and humid, they added Rapid Set® SET Control retarding admixture to the mix water to extend initial working time by 10 minutes to 20 minutes.
They were a well-oiled machine by the time they moved on to the midfield repairs, and the airport reopened on time each morning.
“Using CTS products allowed us increase the amount of work completed in a short work window and still meet opening strength requirements,” Schopf says.
These photos show the process.