Hot-Mix Asphalt Overlay Design Concepts for Rubblized Portland Cement Concrete Pavements

Abstract

The Illinois Department of Transportation’s (IDOT’s) first interstate rubblization project was constructed in 1990 on I-57 near Pesotum as part of a rehabilitation study. Hot-mix asphalt overlays (HMA OL) were constructed over a rubblized jointed reinforced concrete pavement (JRCP) with a granular subbase. Excellent performance was achieved on the project, which had accommodated 7.5 million equivalent single-axle loads through 1998. Periodically collected falling weight deflectometer (FWD) data indicate the sections have retained their structural capacity and integrity. HMA fatigue distress has not developed. The success of the project prompted IDOT to consider portland cement concrete pavement (PCCP) rubblization and HMA OL a viable and cost-effective rehabilitation option. Rubblization is particularly appropriate for eliminating reflective cracking and for use when PCCP patching quantities are high or concrete deterioration is in an advanced stage. HMA OL fatigue considerations control the HMA OL thickness requirement for rubblized PCCPs. HMA OLs for rubblized PCCPs, generally in the 150-mm to 250-mm (6-in. to 10-in.) range, are thicker than those used in the traditional PCCP rehabilitation and HMA OL projects. IDOT uses mechanisticempirical (M-E) flexible pavement design procedures for full-depth asphalt and conventional flexible pavements. M-E–based HMA OL design procedures for rubblized PCCPs are being developed. In the M-E design procedures, the tensile strain at the bottom of the HMA layer is used to consider HMA fatigue. The structural behavior and HMA OL fatigue performance of the Pesotum sections are used in the initial development of the M-E–based HMA OL design procedures for rubblized PCCPs. Results from other rubblized PCCP projects are being used to refine and validate the M-E design concepts.