There is a critical need to identify and develop reliable designs and construction techniques for full-depth repair load transfer systems. To address this need, a laboratory study was designed and performed to estimate the effects of several dowel load transfer systemdesign and construction variables on dowel deflection and the development of dowel looseness. The laboratory study involved the application of 600, 000 or more bidirectional, 3, 000-lb (13.4-Kn) shear loads to single dowels anchored in holes drilled in concrete specimens. Test variables included dowel diameter, drill diameter and impact energy, anchor material, and dowel embedment. A thin nylon disk was placed around each of these dowels at the face of the concrete to retain the anchor material in the drilled hole until it could harden. Tests were also conducted using cast-in-place dowels, hollow stainlesssteel dowels, and dowels installed in very tight holes. Applied load and dowel deflection data were collected and analyzed to produce models for dowel deflection and looseness as functions of the test variables. One key finding of this study is that the dowel must be anchored firmly and supported uniformly to perform well. This can be accomplished by using thin, snug-fitting disks to retain the anchor material in the drilled hole during curing. This type of device shouldbe used for all field installations to improve the performance of properly designed and constructed repairs. This paper appears in transportation research record no. 1215, Pavement management and rehabilitation.
Abstract