Structural Characterization of Iowa's Rubblized PCC Pavements

Rubblization is considered one of the sustainable surface preparation techniques before placing a hot mix asphalt (HMA) overlay that involves breaking the concrete pavement into pieces. The design of the structural overlay thickness for rubblized projects is difficult as the resulting structure is neither a true rigid pavement nor a true flexible pavement. The most important aspect of the design procedure is to characterize the rubblized concrete layer in terms of a layer coefficient and modulus for the empirical and the mechanistic-empirical (M-E) pavement design methods. This paper describes a field study undertaken to investigate the performance of rubblized pavements in Iowa, which includes characterization of the rubblized Portland cement concrete (PCC) layer (layer coefficient and modulus) using a neural networksbased layer moduli backcalculation program. The average rubblized PCC layer coefficient and backcalculated modulus of the rubblized layer in Iowa were found to be 0.19 and 539 MPa (78 ksi), respectively. The M-E design program developed in-house seems to estimate the HMA overlay thickness reasonably well to achieve long-lasting performance of HMA-overlaid rubblized PCC pavements. CE Database subject headings: Pavement design and rehabilitation, Rubblization, Portland cement concrete, Neural Networks, Hot Mix Asphalt, Mechanistic-Empirical Design