Click for next page ( 2

The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement

Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 1
1 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).