In August 2004, a demonstration project to install an Ultra-Thin White-topping (UTW) overlay, which IDOT could test and monitor over time, was undertaken by SCCI. A steering committee of several associations and volunteers soon formed to develop a specification and a concrete mix design. Historically IDOT had been unwilling to specify concrete white-topping projects because it considered them to be experimental pavement--DOT will specify only products and systems that it can accept liability for. An impressive achievement of this demonstration project was the large number of businesses and associations that volunteered their effort. Never in Chicago's history have so many competing ready mix companies worked together on a project that benefited the state of Illinois and its taxpayers. SCCI supplied labor and a 3-D Laser Screed to place the concrete that was from 2 to 6 inches thick over an area of 41,000 sq.ft. The 6 inch lane was used for heavy truck traffic and, because of drainage issues, the project was 3-D Profiled. Ten workers placed and finished concrete, while two workers applied curing and laid out joints, and two workers did most of the sawing over the two day demonstration. There were two reasons for placing the 2-inch overlay: Not enough structural asphalt was left after roto-milling to provide space for 4-inch concrete in the handicap parking and wheelchair ramp areas, and IDOT wanted to study the structural capabilities of a 2-inch-thick overlay over time. Control joins were cut utilizing early entry saws, based on ACI specifications for depth, since the project required areas with 2”, 3”, 4”, and 6” depth. This project received numerous accolades.
