Analyses of Top-Down Cracking in Rubblized and Flexible Pavements
Principal Investigator:	Gilbert Y. Baladi
Research Assistant:	Tunwin Svasdisant
Funding Agency:	Michigan Department of Transportation

Top-down cracks (TDC) are longitudinal and/or transverse cracks that initiate at the pavement surface and propagate downward and outward as shown in Figure 1. TDC have been reported as a major distress in flexible pavements in several countries including the US. This study includes investigations of rubblized and flexible pavements and mechanistic analyses of load- and environmental-induced stresses in the AC layers of the two types of pavements. The investigation of the rubblized and flexible pavements includes:

• Examination of the rubblized concrete slabs during construction (Figure 2);
• Falling Weight Deflectometer (FWD) test and distress survey;
• Laboratory tests to assess the engineering and physical properties of AC specimens obtained from the field (Figure 3); and
• Backcalculation of pavement layer moduli.

• Svasdisant T., Schorsch, M., Baladi, G.Y., and S. Pinyosunun, "Mechanistic Analysis of Top-down Cracks in Asphalt Pavement," Transportation Research Record 1809, TRB, National Research Council, Washington, D.C., 2002, pp 126-136
• Baladi, G. Y., and Svasdisant, T, "Identify Causes for Underperforming Rubblized Concrete Pavement Projects," ”, Research Report MSU RC-1416, Michigan Department of Transportation, Lansing, Michigan, 2002