252 SECTION 575
575.01 Description
This work consists of performing a dowel bar retrofit in concrete pavement.
575.02 Equipment
Item Section Concrete Equipment 155 Air Compressor 156.01 Use a gang saw capable of sawing all required slots on a transverse joint or crack in the wheel paths of a single lane of the pavement simultaneously. The gang saw should be able to cut the slots parallel to the direction of traffic flow and parallel to one another.
575.03 Materials
Item Section Portland Cement Concrete 802 Grout and Epoxy 806 Class 5 Aggregate 816 Joint Materials 826 Reinfor cing steel 836.02 Dowel bars 836.04
A.Patching Material Mix Design. Mix and place the patching material as specified by the manufacturer. Select one of the following patching materials: − Five Star Highway Patch; − Burke 928 Fast Patch; − American Highway Technology’s dowel bar retrofit mortar; or − An approved equal. A minimum of 5 working days before beginning dowel bar retrofit work, submit the manufacturer’s product literature and a concrete mix design for the patching material that meets a minimum compressive strength of 4,000 psi in 6 hours. Include all additives and materials to be used in the mix design.
B.Dowel Bars. Use dowel bars with tight fitting end caps made of nonmetallic materials that allow for 1/4 inch movement of the bar at each end. Submit sample end caps to the Engineer before use. Use support chairs that are non-metallic or that are epoxy coated as specified in ASTM A 775. 253 C. Caulk. Use a caulk for the crack at the bottom and sides of the slot that is compatible with the patch material being used.
D.Foam Core Board. Use foam core board constructed of closed cell foam faced with poster board material or laminate on each side.
E.Curing Compound. Use a wax -based liquid membrane-forming curing compound as specified in ASTM C 309 that conforms to the requirements of Type 2, Class A or B.
575.04 Construction Requirements
A.Jack Hammers. If using jack hammers, use 30 pound class or smaller jack hammers.
B.Cleaning. Sandblast exposed surfaces and cracks in the slot. Clean the slot of saw slurry and deleterious material before installing the dowel.
C.Joint Caulking. Caulk the existing transverse joint crack at the bottom and sides of the slot to provide a tight fit for the foam core board and prevent patch mix from entering the crack. Do not extend the sealant on the face of the slot more than 3/8 inch of each side of the existing transverse joint crack.
D.Dowel Bar Placement. Place the dowel bar, parallel to the centerline, and parallel to pavement surface of the lower panel at the transverse joint, to a tolerance of 1/4 inc h. Center the dowel bar above the existing joint within a tolerance of one inch.
E.Mixing Patch Material. Mix the patch material with a hand mixer. Do not use a mobile mixer. Add water using a metering or measuring device. Produce patch mix of uniform texture and consistency. Produce a test batch a minimum of 1 working day before production of patch material begins. Use the same materials and equipment that will be used during production. The Engineer will produce cylinders and verify the compressive strength of the material before allowing full production. The Engineer will test the patching material for compressive strength once for each four hours of production. If compressive strengths are not being met, cease production and resubmit a mix design correcting the strength problems.
F.Slot Surface Preparation. Place the patch mix on a dampened concrete surface and ensure there is no ponding in the bottom of the slot.
G.Placing Patch Mix. Place the patch mix into the slot and vibrate it with a small hand -held vibrator. Prevent material from entering the joint surrounding the slots. Completely fill up the slots, including the area under the bar.
H.Curing. Place curing compound on a set of dowel bar retrofits in single wheel path no more than 30 seconds after the retrofits have been finished.
I.Opening to Traffic. Before opening the repaired lane to traffic, perform grinding as specified in Section 570.04 C, “Grinding” .
575.05 Method of Measurement
The Engineer will measure, completed and in place, as specified in Section 109.01, “Measurement of Quantities”, and as follows: The Engineer will measure each dowel bar installed as “Dowel Bar Retrofit”. Grinding will be measured as specified in Section 570.05, “Method of Measurement” .
575.06 Basis of Payment
Pay Item Pay Unit Dowel Bar Retrofit Each Such payment is full compensation for furnishing all materials, earthwork, equipment, labor, and incidentals to complete the work as specified. Grinding will be paid for as specified in Section 570.06, “Basis of Payment” . Section 602 255 SECTION 602 CONCRETE STRUCTURES
602.01 Description
This work consists of the construction of bridges, cast-in -place box culverts, and cast-in -place retaining walls.
602.02 Equipment
A.General. Do not use aluminum tremies, forms, hoppers, downspouts, or chutes. Use a batch plant and equipment as specified in Section 155, “Concrete Equipment”.
B.Deck Finishing Equipment. Use a deck finishing machine as specified in Section 155.07 C, “Bridge Deck Finishing Equipment ”.
C.Sandblasting Equipment. Use compressed air type sandblasting equipment to clean concrete surfaces.
D.Water -Washing Equipment. Use water washing equipment that meets the requirements of one of the following: − A water pressure washer with a minimum of 160°F water at 1,800 psi minimum nozzle pressure; − A hydroblast washer using water at 7,000 psi minimum nozzle pressure; or − A steam cleaning unit using a minimum of 320°F water at 305 psi minimum operating pressure.
E.Curing Concrete. Use a fogging machine as specified in Section 156.02, “Fogger” for exposed surfaces.
F.Shot Blasting Equipment. Use centrifugal or wheel type shot blasting equipment that is designed to clean concrete surfaces and leave no oil or other foreign material on concrete surfaces. Use a shot blaster capable of collecting blast media and dust.
602.03 Materials
A.General. Item Section Portland Cement Concrete 802 Epoxy Resin Adhesives 806.02 Burlap Cloth 810.01 A Penetrating Water Repellent 822 Preformed Expansion Joint Fillers 826.02 C , D, or F Sealant 826.02 B.1
Source: North Dakota Standard Specifications for Road and Bridge Construction, 2022 Edition. Pages 287–289 of 550.