The objective of this study is to develop guidelines and criteria for design and construction of overlays on cracked and seated concrete pavements. The main factors which are investigated in this study include number of the seated roller pass, weight of seating roller pass, weight of seating roller, thickness of overlay, fiber content and fiber layer location. Eleven test sections were constructed on I-65 and twenty two test sections were constructed on US-31. An extensive investigation was conducted involving both field and laboratory testing. Field investigations included pavement condition survey and non destructive testing (NDT) of the pavements using FWD or Dynaflect. The laboratory investigation focused on physical property testing, complex modulus testing and fatigue testing. Three fiber extraction methods have been developed for this project. Preliminary test Results show good precision of these methods. These fiber extraction methods should be used in future projects. Deflection measurements can be used to determine the appropriate weight and drop height of the breaking head. The Guillotine breaker used in this project is effective in breaking PCC pavement. A 40 ton roller is recommended because the 50 ton roller apprears to “overwork” the crack concrete pavement. Roller passes have no significant effect on the maximum deflections. The optimum roller pass can not be determined exclusively based on the maximum deflections. One to three passes of a 40 ton pneumatic-tired roller is adequate when seating is needed to assure contact of cracked pavement pieces with the subgrade. Use of fiber and the fiber layer location do not have a significant effect on pavement strength in term of the maximum deflection. But use of fiber will delay the crack development. The least cracks were developed in the sections which have fiber in all three layers. It is recommended that fiber be used in all overlay layers. Overlay thickness has an important effect on the maximum deflections and the development of reflective cracks. General trends of crack development showed in the first two years. Cracked and seated sections have less cracks than non cracked and seated sections, with other conditions being the same. The general trends are not obvious after two years. Beams of 3x3 in. are recommended to be used for the flexural fatigue tests in the future due to small variability. Addition of fiber increase the fatigue life of overlay mixture. Composite samples with fiber (4.5 lb) have predicted fatigue life two times greater than those without fiber. Loading frequency and temperature have significant effects on dynamic modulus and phase angle of overlay mixture. The addition of fiber will change the viscoelastic properties of mixture.

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crack and seat, overlay design, fiber, reflective crack, deflection, condition survey, flexural fatigue test, complex modulus test, HPR-2041

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Performing Organization

Joint Highway Research Project

Publisher Place

West Lafayette, IN

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