When portions of two busy Kansas interstates, I-70 and I-635, were due for repair, the Kansas DOT (KDOT) needed a patching solution that would help accelerate the project and minimize road closures. Because I-70 is a major highway and I-635 is a heavily traveled spur, the patching needed to be completed between 8 p.m. and 5 a.m. so the roadway could open before the morning rush hour.
Like many state transportation departments, KDOT had been using concrete with a high content of type I/II portland cement for their repair projects. Although KDOT did not specify the concrete when seeking bids, the project plan originally called for a portland cement-based concrete with a high dose of admixtures, which would be needed to achieve early strength.
“Portland cement doesn’t gain strength rapidly,” said Matt Ross, engineer for CTS Cement. “It also has high shrinkage.”
RA Knapp Construction, the contractor awarded the two patching projects, proposed Rapid Set cement as an alternative solution. Rapid Set cement is a calcium sulfoaluminate (CSA) cement developed to address some of the shortcomings of portland cement. Unlike concrete with a high portland cement content, Rapid Set cement has early strength gain and very low shrinkage. This can lead to better durability and a longer life expectancy. And, the fast-setting properties enable crews to perform considerably more work, while still completing the project on time.
KDOT field engineering administrator Amy Pope said that prior to RA Knapp’s proposal, KDOT had previously approved Rapid Set cement in bag mix, but never for bulk use. After the project was completed, they wrote specifications for future use and deemed the project a success.
