Print this page Print this page

Dowel Bar Retrofit

John Poullain, P.E.


Course Outline

This two-hour online course describes the pavement load transfer through dowel bar retrofits (DBR) to maintain and preserve concrete pavements. The Caltrans text can serve as a reference and ranges from general instructions to specific practices for the procedures. Topics discussed are the selection and use of concrete materials, dowel layout and placement, construction processes, pavement distress types, checklists, and troubleshooting guides. Photographs and drawings illustrate the treatment techniques.

This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials.

Learning Objective

At the conclusion of this course, the student will have covered these topics:

Intended Audience

This course should benefit civil engineers, pavement engineers, transportation engineers, field and office personnel, supervisors and maintenance personnel.

Benefit to Attendees

The student will become familiar with he pavement load transfer through dowel bar retrofits (DBR) to maintain and preserve concrete pavements. .

Course Introduction

Pavement preservation has become more important for maintaining the national highways. FHWA and its partnership with states and other agencies have realized the benefits of preservation systems which equate to better pavement performance, safety and increased pavement life. The goal is to address pavement problems before more serious damage occurs. FHWA guidelines were developed for DBR as one technique to effectively restore slab integrity, rideability and to extend the pavement service life.

The course text discusses the methods, pavement distresses, design considerations, construction processes and equipment used, project checklists and troubleshooting guides. Factors which influence performance, weather, maintenance and construction activities are considered.

As a vehicle travels on jointed concrete pavement the weight passes from one slab to the next. The weight pressing on the slab edge will cause deflection of a slab which does not have inadequate shear resistance resulting in a joint fault. Earlier attempts to transfer vehicle loads from slab to slab used steel rods to connect the slabs. The practice was discontinued as steel rods corroded, requiring replacements. Pavement integrity then relied on cohesion between the slabs and the strength of the roadbed. Since then dowel bars are now epoxy coated to give corrosion protection for longer life. They have also been engineered as complete assembly units for insertion in a slot designed and cut as specified for the locations.

Dowel bar retrofits do occasionally have problems as noted in the text. The typical problems include:

  1. Poor workmanship.

 a. Improperly cutting the slots - overcutting, undercutting, and misaligning.
 b. Poor cleanout of the slots.
 c. Improper placement of the DB assemblies and slot backfill.                   .

2. Jackhammer too heavy. This can cause pavement cracking around the slots or too deep a slot.

3. Lack of or insufficient caulk in the joints or cracks at the slot intersections.

4. Voids in the slot backfill material.   

 

Course Content

The course is based on the Caltrans MTAG Volume II publication “Chapter 6 - Dowel Bar Retrofit”, (2008 Edition, 28 pages), PDF file.

Caltrans MTAG Volume II publication “Chapter 6 - Dowel Bar Retrofit”, (2008 Edition, 28 pages)

Please click on the above underlined hypertext to view, download or print the document for your study. Because of the large file size, we recommend that you first save the file to your computer by right clicking the mouse and choosing "Save Target As ...", and then open the file in Adobe Acrobat Reader. If you still experience any difficulty in downloading or opening this file, you may need to close some applications or reboot your computer to free up some memory.

Course Summary

This course should serve as a guide to assist pavement engineers, field personnel and others. The course describes the construction, treatment procedures, construction equipment, best practice hints and materials used for the dowel bar retrofit repair procedures. Checklists, troubleshooting guides, solutions and helpful websites are included in the text and below.  

Related Links

For additional technical information related to this subject, please refer to:

http://www.fhwa.dot.gov/pavement/desi.cfm
FHWA website discusses design, construction, and maintenance of US pavements.

http://www.vulcanhammer.net/geotechnical
Offers geotechnical downloads for various manuals from FHWA, Dept. of the Interior, US Army Corps of Engineers and papers submitted by collages and PE’s. Case studies, recent developments and downloadable software are available.

http://techtransfer.berkeley.edu/pavementpres/#@pelim
UC Berkeley Institute of Transportation Studies for pavement preservation and maintenance.
 
http://igga.net/CaseStudiesFactSheets.cfm
Case studies for DBR from state IDOT’s by International Grooving & Grinding Asc.

Quiz

Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.

DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.