Structural Adequacy of Rubblized Portland Cement Concrete Pavement

Abstract

The objective of rubblization is to eliminate reflection cracking in hot-mix asphalt (HMA) overlay by the total destruction of the existing slab action. Rubblization is applicable when there is little potential for retaining slab integrity and structural capacity of the original jointed reinforced concrete pavement. Rubblization has been used successfully for rehabilitation of other portland cement concrete (PCC) pavement types. Typically, the slab is reduced to pieces less than 300 mm in size. Subsequently, the slab is converted to a high-strength granular base. Restoration of the structural capacity is accomplished with an overlay of HMA. In 1991, the Indiana Department of Transportation (INDOT) awarded a contract to apply the rubblization technique to a portion of US-41 in Benton County. The pavement sections were evaluated before and after rubblizing and overlay to estimate the AASHTO layer coefficient of rubblized concrete pavements. The layer coefficient determined in this study ( a2 = 0.25) represents a value of two standard deviations less than that reported by PCS/Law. Currently, INDOT uses a layer coefficient of 0.20 for rubblized PCC pavements. On the basis of the results of this study, the layer coefficient can be set within two standard deviations of the mean (i.e., 0.22). This layer coefficient of 0.22 represents a conservative value that is recommended for rubblized PCC pavements with similar conditions. If INDOT continues to use the rubblization technique in pavement rehabilitation, a study encompassing slabs of different thicknesses on different subgrades should be undertaken for confirmation of the values that are reported herein.