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CHAPTER 1
Background
1.1 Problem Statement 1.2 Scope of Study
Dowels are used in jointed portland cement concrete (PCC) The research was conducted to develop guidelines con-
pavements to provide load transfer, reduce faulting, and cerning dowel alignment in concrete pavements. The effects
improve performance. These dowels are placed either manu- of dowel misalignment on pavement performance were eval-
ally before concrete placement or during construction by uated through a literature review; laboratory tests of indi-
automatic dowel bar inserters to expedite construction and vidual dowels; field measurements of misalignment levels,
reduce cost. Inspection of pavements in several states revealed distresses, and joint performance; and finite element modeling
that misalignment of dowels generally occurs regardless of of pavements with different types and levels of misalignment.
the placement method. These inspections also revealed that The laboratory tests dealt with dowel-concrete interaction
slab cracking and other forms of distress may not always occur of individual dowels to evaluate the effects of specific types
as a result of such misalignment. However, limited research has and levels of misalignment in a controlled environment.
been performed to determine the extent of dowel misalignment Pullout testing was conducted on individual dowels to iden-
in pavement construction and its effect on performance. tify the misalignment's effect on expansion and contraction
This report presents the research conducted under NCHRP of the concrete due to shrinkage and thermal effects. Indi-
Project 10-69 to address the issues associated with dowel vidual shear-pull testing was conducted to determine the
alignment and develop approaches for estimating the effects effect of different types and levels of misalignment on ultimate
of different levels and types of misalignment on performance, shear strength and stiffness. Finite element modeling was
thus improving the analysis and design of concrete pavements. used to augment the results of the laboratory study. An equiv-
The objective of this research is to develop guidelines for dowel alent dowel diameter concept was developed to facilitate
alignment in concrete pavements. The research addresses all quantifying the effects of dowel misalignment on pavement
forms and combinations of dowel misalignment (i.e., vertical performance.
and lateral skew and displacement).
