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Forensic Investigation of Cracking in a Portland Cement Stabilized Full Depth Recycled Pavement


The Point Michaud Beach Road was the first Portland cement stabilized Full Depth Recycled (PC-FDR) asphalt pavement project conducted in Nova Scotia. Several modes of cracking have developed on the pavement surface over the past two years. Excessive transverse shrinkage cracks have developed across each stabilized mat. These cracks were expected, but not to the extent that have been observed, despite the use of a micro-cracking construction process that was used to mitigate shrinkage effects. Multiple parallel longitudinal cracks along the pavement centreline and shoulder edge cracking have appeared along the majority of the pavement section. An impulse-response survey and a coring investigation were conducted on the pavement section in 2009 in order to evaluate the effects of this distress on the structural properties of the road. The extent of damage across the section at various locations was determined to explore a rationale for the cause of the cracking. It was concluded that slab overloading during the micro-cracking process probably contributed to the development of the excessive structural cracking, while high cement content contributed to excessive shrinkage cracking. Stress analysis of loads applied during the micro-cracking process indicated that the maximum slab stress in two load configurations exceeded the PC-FDR modulus of rupture. Prevention of micro-cracking roller patterns from overlapping the PC-FDR and adjacent shoulder and/or unbound pulverized materials, and overlap between lanes on the pavement crown, were recommended to avoid rupturing the stabilized base layer. 

Conference Paper Details

Session title:
Christopher L. Barnes