I’m a roller coaster, carousel, and general amusement park enthusiast, and I recently returned from a trip that included a stop at Kings Island in Kings Mills, Ohio (near Cincinnati). I didn’t see any concrete markings there, but I did find this brick with the logo of Hicon, Inc. in the Oktoberfest area. There were several such bricks set here and there in the brick walkway.
Hicon is a masonry and paving contractor based in Cincinnati. According to their About Us page, they were founded in 1977, the same year the Demon roller coaster (now defunct) opened at Kings Island, and a couple of years before the famous Beast.