Asphalt concrete overlays on CRCP : decision criteria, tack coat evaluation, and asphalt concrete mixture evaluation.

PDFTech Reporthttp://ctr.utexas.edu/wp-content/uploads/pubs/0_4398_3.pdfFHWA/TX-05/0-4398-3Overlays (Pavements)Bituminous overlaysAsphalt concrete pavementsTack coatsTexasTexas. Dept. of Transportation. Research and Technology Implementation OfficeTrevino, ManuelKim, Seong-MinSmit, AndreMcCullough, B. FrankYildirim, YetkinUniversity of Texas at Austin. Center for Transportation ResearchTexas. Dept. of Transportation. Research and Technology Implementation OfficeUnited States. Federal Highway AdministrationUS Transportation CollectionThis report presents the research undertaken within two areas of study of thin asphalt concrete (AC) overlays to rehabilitatecontinuously reinforced concrete pavements (CRCP). The first one is the development of a decision tree for the projectselection of a rehabilitation of this kind. The second area is the testing of tack coats and AC mixtures for its use in ACoverlays.Within the first area, several decision criteria, based on the functional and structural characteristics of the existing pavement,were developed to evaluate the technical suitability of AC overlays on CRCP. These criteria are, namely, a profile criterion,based on the remaining life concept and on the formulation of a dynamic load factor; a condition survey criterion, whichutilizes a pavement distress index and the rate of failures per mile per year; and a deflection criterion, which evaluates thehypothetical contribution of an AC overlay based upon deflection measurements performed on the existing structure.The second part of the study investigated the interface shear strength of tack coats used for bonding AC and portland cementconcrete pavement (PCCP), and the rutting resistance of asphalt mixtures for use as overlays on CRCP. A shear test wasdeveloped for the tack coats experiment, and it was found that mixes with finer gradations appear to improve the shearstrengths of tack coat interfaces. Based on the results of the rutting resistance tests, it is recommended to use Superpave,CMHB, and Type C mixes for AC overlays on CRCP, and to avoid using siliceous river gravel aggregates in these mixes,because of its inferior performance