Premature Failure of Concrete Patching: Reasons and Resolutions

About the report:

The performance of concrete patches in continuously reinforced concrete pavement in Virginia varies from less than 1 year to many years.  The purpose of this study was to determine the causes of premature repair failure in continuously reinforced concrete pavement. 

Four pavement sections were monitored for patching operations.  Mixture designs had high cementitious material contents. The patches were typically constructed with a short lane closure time, often at night, with only about 5 to 8 hours of cure time before opening of the roadway to traffic.  The strengths were determined using the temperature matched curing system.  The observations and testing indicated that the two of the most significant causes for premature failure were (1) the use of high early strength concrete mixtures with high cement contents that cause excessive thermal and shrinkage cracking, and (2) failure to assess the overall pavement condition, which could have led to an overlay with structural improvement rather than just patching.  Some other areas of concern were cutting of the continuous reinforcement, reestablishing the continuity of the reinforcement in the patch, damaging concrete adjacent to the patch during concrete removal, poor concreting practice with respect to proper consolidation of the concrete near the joint, and opening to traffic before adequate concrete strength was achieved.

Based on these findings, the study recommended revisions to future special provisions for concrete patching and the VDOT Materials Division Manual of Instructions, Chapter 6.  

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