Development of Asphaltic Concrete Overlay Design Procedure for Rigid Pavements in Indiana : Executive Summary

Abstract

An overlay study was conducted of thirty jointed reinforced concrete pavements (JRCP) and thirteen continuously reinforced concrete pavements (CRCP). These pavements were selected from the Indiana primary highway system based on an experimental design for levels of major factors affected pavement performance. An analysis was made of pavement deflection; condition; serviceability; materials; thicknesses; truck traffic; latest overlay thickness; age; climate zone and subgrade type, density and moisture content. Initially, a rational analysis was planned using a back calculated material properties as suggested in the 1986 AASHTO Design Guide. However, this approach was not successful and alternate analysis procedures were utilized. The performance of asphalt overlays of concrete pavement proved to be complex. Fortunately, analysis of the database built using experimental design techniques helped to explain this complex performance. Based on the performance data several performance regimes were characterized. For example, increased overlay thickness for jointed concrete pavements on stiff foundations was characterized by a relation using a PCI subset of cracking distresses. A statistical analysis was performed on the CRCP pavement data, and an overlay model was developed. However, because of the limited range of thickness, truck, traffic, etc., the equations should be used only as a guide for determining overlay thickness. Two statistical models were developed for the JRCP sections. This first is a structural model, to be used for thin to medium-thick (6” to 9”) Portland cement concrete (PCC) pavements with thin asphalt concrete (AC) overlays. The second is a functional model, to be used with thick (>9”) PCC pavements or an PCC pavements with thick (>5”) AC overlays. A procedure has been formulated for determining which of these equations is applicable for particular AC/PCC thickness combinations.