DOWEL BAR BASKET ASSEMBLIES
LOAD TRANSFER DOWELS
1. Dowels shall be plain, round bars meeting one of the following requirements:
a. ASTM A 615/ A 615 M, grade 40 or grade 60
b. ASTM A 675/ A 675 M, grade 60 or higher
c. ASTM A 663/ A 663 M, grade 60 or higher
2. Only approved or pre-approved fabricators can supply load transfer dowels and dowel assemblies to Iowa DOT projects. Approved fabricators are listed in this appendix.
3. Dowels (with exception of end of run and header joints) in approved assemblies shall be suitable for skewed or perpendicular joints as approved by the shop drawings.
4. Dowel assemblies/load transfer dowels shall meet the full requirements of the standard road plan PV-101.
5. Dowels, end of run and header dowels shall be epoxy coated by the electrostatic spray methods in compliance with the requirements of ASTM A775/ A775M. Epoxy coating shall be performed by and Iowa DOT approve coater ( approved coaters are listed in IM 451.03B, Appendix A), and approved epoxy powder ( approved powders are listed in IM 451.03 B, Appendix B)
6. The minimum thickness of the epoxy coating shall not be less than 6 mils after cure.
7. The end of the dowel may be saw cut or sheared. The saw cut and/or sheared ends shall be free of sharp edges and free of burs and projection. Dowels shall be true round shape and deformation (if any) shall not exceed 0.004 inches (1mm) in diameter or thickness.
8. Dowel assembly details (dowel heights, diameter, length, wire size, welding, tolerances, etc.) can be found in detail in PV-101
With each shipment, the supplier shall furnish a letter of compliance identified with the county, project number, and contractor. This letter shall itemize the following:
1. Quantity of material shipped
2. A certification statement that assures the material was fabricated in accordance with approved shop drawings, and indicates the approval date of the drawings
3. A statement for epoxy coating shall include the name of the coating company, compliance with ASTM A775, and indicate that the coating reports for the material are retained in the files of the assembly supplier (subject to review by the Iowa Department of Transportation).
4. Copies of Mill Test Reports (including heat numbers) of all steel used in the fabrication of the dowel assemblies shall be required with each shipment to each project and all records of the assemblies shall be maintained by the fabricator and/or supplier for a minimum of three years.
5. Epoxy coating of the dowels shall be performed by an approved coater and applied with an approved powder. Epoxy coating records shall accompany each shipment to each project and shall be maintained by the fabricator and/or supplier for a minimum of three years.
6. All steel used in the fabrication of the assembly including the anchor pins shall be of a domestic origin, melted and manufactured in the U.S.A.
7. Fabricators of the dowel assemblies shall be fully responsible for complete and unconditional compliance with the requirements of the Iowa DOT Standard Road Plan PV101.
Prior to delivery to project site, the entire assembly shall be dipped in a bond breaker holding tank meeting the following requirements:
A. Bituminous Bond Breaker:
1. Section 4137 (Asphalt Binder)
2. Section 4138 (Cut back or Liquid Asphalt)
3. Section 4140 (Emulsified Asphalt)
B. Approved Paraffin Base or Wax Base Lubricant Bond Breaker or Solvent
1. TectyL 506*
· *TectyL 506 is a solvent/cutback corrosion preventive compound made by Daubert chemical company of Chicago, Ill.
· Is formulated to be used as supplied ( continuous stirring is generally not required)
· TectyL 506 cannot be thinned.
· Recommended ambient temperature for TectyL 506 is between 50° and 95° F at the time of application.
· TectyL 506 cannot be allowed to freeze. It should be stored (in the winter months) at temperatures over 50°.
· TectyL 506 can be spray or dip applied.
· Sample frequency 1.0 sample per fabricator/year. Additional samples may be secured for testing and verification.
2. Bradley Coating Group (BCG 6116 DSMA)
· Bradley Coating is a bond breaker.
· Bradley Coating is a corrosion preventative compound.
· Storage and application at room temperature between 50 and 95° F.
· Mild agitation is necessary prior to application.
· BCG 6116 DSMA can be thinned with either/or one of the following solvents to maintain the recommended liquid viscosity:
a. Tert-butyl acetate (TBA)
b. Mineral spirit
c. Methyl acetate (MA)
· Once the solvents evaporate, the dry film is left for protection.
Dowel Bar Size Dowel Bar Diameter
#6 (#20) 3/4-inch (19 mm)
#10 (#30) 1 1/4-inch (31 mm)
#11 (#35) 1 1/2-inch (38 mm)
The Iowa DOT requires all welding/any type of welding to be performed by:
1. Certified welder and certified tack welders.
2. Approved weld procedures (WPS)
Welding and Tack welding of steel reinforcement shall meet the requirements of IM 558, Section XIII, the requirements of Article 2407.03E.2 and all other requirements as outlined in the latest edition of AWS D1.4 including the requirements for the pre-heat and interpass temperature with the exception that the minimum temperature cannot be dropped below 50°F(10°C)
NOTE: Manual and automatic tack welding (Robat) operators shall be qualified in any process that the fabricator is using.
STORAGE AND HANDLING
Epoxy coated dowels in dowel assemblies stored outdoors longer than two months either at the fabricator or at the project site shall be protected from sunlight, salt spray, and weather exposure. The coated dowels in the dowel assembly shall be covered with a non-transparent or other suitable opaque protective material. Provision shall be made for adequate ventilation to minimize condensation. The date of which the coated dowels assemblies are placed outdoors, shall be recorded on an identification tag. Weathered / discolored / faded dowel bars shall be rejected. Visual inspection for acceptance and / or rejection shall be at the discretion of the District Materials Engineer.
Dowell assemblies shall be stored off the ground on a wood / timber support. When stacking is necessary, wood / timber support shall be placed between assemblies.
Dowell assemblies shall be in full compliance with the specification requirements (size, dimensions, tolerances, spacing, bond breaker, etc.) prior to the commencement of the paving process.
SUPPLIERS (FABRICATORS) LOCATION
Alton Steel, Inc. (ASI) Alton, IL
Ambassador Steel Corporation* Des Moines, IA
(Fabricator: Dayton Superior, Inc.)
(Fabricator: Wady Industries)
Construction Materials, Inc.* Cedar Rapids, IA
(Fabricator: Construction Materials, Inc.) Des Moines, IA
(Fabricator: Construction Materials, Inc.) Minneapolis, MN
(Fabricator: Wady Industries) Maquoketa, IA
Dayton Superior, Inc. Kankakee, IL
Logan Contractors Supply, Inc. Des Moines, IA
(Fabricator: Blue Grass Steel Company)
(Fabricator: Wady Industries)
(Fabricator: Erect-A-Line, Inc.) Dallas, TX
Wady Industries Maquoketa, IA