Minimizing Reflective Cracking With Applications of the Rolling Dynamic Deflectometer and Overlay Tester

Since reflective cracking is related to both the existing pavement condition and the properties of the overlay material, quantitative methods are required to assess both the vertical movements of the cracks (or joints) for the entire project and the reflection cracking resistance of the overlay material. Since 2000, the rolling dynamic deflectometer (RDD) has been used in Texas to provide 100 percent coverage of existing joint conditions of concrete pavements being considered for asphalt overlays. The RDD assesses the vertical movements of each joint and identifies the weak support areas and locations where the slabs are rocking. The continuous deflection profiles produced are used to locate areas with high potential for reflective cracking due to poor load transfer and high slab movements. The overlay tester (OT) has been developed as a mix design tool to characterize the ability of an asphalt mix to resist reflective cracking. OT results have not yet been integrated with RDD results to predict the exact extent of reflective cracking that will occur. However, OT results are still good for ranking various mixtures in terms of crack performance, and some guidelines based on OT and RDD results have been developed. This paper presents a series of case studies illustrating the relationship between the RDD deflection profiles, the OT results of the asphalt mixes, and the resulting field performance. On IH-20 experimental sections in northeast Texas, the RDD identified many locations that have high potential for reflective cracking. The mix used on this project was found to have poor crack resistance and failed the overlay test quickly (2 cycles). Major reflection cracking problems were encountered on this project. At another project, SH-12 in the Beaumont District, no visible cracks have been observed after 2 years of service, despite significant movement detected by RDD. The main reason for the good performance on SH-12 is believed to be due to the thick and flexible overlay mix (the mix lasted more than 900 cycles in the OT). On a section of US-96 in the Beaumont District, the RDD determined that the pavement had good load transfer efficiency across the cracks, and consequently was at low risk of reflection cracking, even though the surface condition was poor, with severe transverse cracks and spalling. A stone matrix asphalt mix with OT life exceeding 700 cycles was placed 5 years ago, and performance to date has been excellent. Based on these case studies, TxDOT has developed criteria for interpreting the RDD deflection data and for defining the required properties of asphalt overlays to provide good performance.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Features: Figures; Photos; References;
  • Pagination: pp 3-13
  • Monograph Title: Proceedings. National Conference on Preservation, Repair, and Rehabilitation of Concrete Pavements, St. Louis, Missouri, April 21-24, 2009

Subject/Index Terms

Filing Info

  • Accession Number: 01483831
  • Record Type: Publication
  • Files: TRIS, ATRI, USDOT
  • Created Date: Jun 13 2013 8:12AM