Item 257  Diamond Grinding Portland Cement Concrete Pavement

257.01 Description

257.02 Equipment

257.03 Construction

257.04 Final Surface Finish

257.05 Method of Measurement

257.06 Basis of Payment


257.01 Description. This work consists of diamond grinding and texturing Portland cement concrete pavement longitudinally to substantially eliminate joint and crack faulting and to restore proper riding characteristics to the pavement surface.

257.02 Equipment. Provide grinding equipment that is a power driven, self-propelled machine that is specifically designed to smooth and texture Portland cement concrete pavement with diamond blades or diamond impregnated cylinder rings. Mount the blades or cylinder rings on an arbor head.  Provide a grinding head at least 3 feet (0.9 m) wide. Ensure the equipment is capable of grinding the surface in the longitudinal direction without causing spalls or other damage at cracks, joints and other locations. The equipment will be capable of l correcting the pavement profile and providing proper cross slope on the concrete pavement.

Provide equipment with an effective wheelbase of at least 12.0 feet (3.6 m); a set of pivoting tandem bogey wheels at the front of the machine and rear wheels that travel and track in the fresh cut pavement.   Ensure the center of the grinding head is no further than 3.0 feet (0.9 m) forward from the center of the back wheels. It shall also be of a shape and dimension that does not encroach on traffic movement outside of the work area.

Furnish and maintain a profiler conforming to S 1058 for daily use during the grinding operations.  Provide all necessary supplies to fully operate and graph the results of testing the ground pavement for smoothness. The Engineer will verify the profiler according to S 1058.

Remove all grinding residue. Remove solid residue before it is blown by traffic action or wind. Do not allow residue to flow across lanes used by the traveling public or into gutters or drainage facilities.

257.03 Construction. The plans will designate the areas of pavement surfaces to be ground. Grinding of bridge decks and roadway shoulders will not be required unless indicated on the plans or required to provide drainage. Accomplish in a manner that eliminates crack or joint faults while providing positive lateral drainage by maintaining a constant cross-slope between grinding extremities in each lane. Transition auxiliary or ramp lane grinding as required from the mainline edge to provide positive drainage and an acceptable riding surface.

Ensure the operation results in pavement that conforms to the typical cross-section and the requirements specified for the final surface finish, however, it is the intention of this specification that the faulting at joints and cracks be eliminated and the overall riding characteristics be restored within the limits specified. To accomplish the smoothness required, grinding may not be required on 100 percent of the pavement surface.

During initial grinding operations, use the profiler to test the pavement surface as soon as the concrete has been ground full lane width. This initial testing is to aid the Contractor in evaluating the grinding methods and equipment being used. Subsequent to the initial testing, run daily profiles of each day's grinding the next working day.

257.04 Final Surface Finish. Produce a pavement surface that is true to grade with the ground area consisting of a longitudinal corduroy-type texture. Ensure the peaks of the ridges are approximately 1/16 inch (1.5 mm) higher than the grooves with 53 to 57 evenly spaced grooves per foot (174 to 187 per meter).

Measure the finished pavement surface for riding quality.

Produce a mainline riding surface which does not exceed an average profile index of 12 inches per mile (189 mm/km) measured in any 0.10 mile (0.16 km) section, nor any localized surface deviations in excess of 0.4 inches in 25 feet (10 mm in 7.6 m), as measured with the approved profiler.   Use a profile Trace in accordance with the California Test 526, 1978 on file in the Office of Contracts. The Engineer will witness the testing of the pavement surface’s wheel paths. The wheel paths will be located parallel to the centerline of the pavement and approximately 3 feet (0.9 m) measured transversely, inside all lane edges. Maintain the alignment of the profiler with reference to the pavement edge at all times. Re-grind any 0.10 mile (0.16 km) sections with an average profile index greater than 12 inches per mile (189 mm/km) to lower the profile index to 12 inches per mile (189 mm/km) or less.

Provide the necessary traffic control and survey stationing for initial measurements or any subsequent measurements. Measure the entire length of pavement, starting and stopping the measuring equipment when any wheel is within 1.0 foot (0.3 m) of any existing pavement, pressure relief joint or approach slab.

Ensure transverse joints and cracks are flush with adjacent surfaces. The Engineer will visually inspect transverse joints and cracks to ensure that adjacent surfaces are in the same plane. Alignment of adjacent sides of the joints or cracks will be within of 1/16 inch (1.5 mm) of each other to be considered flush. Ensure the transverse slope of the pavement is uniform to a degree that no depressions or misalignment of slope greater 1/4 inch in 12 feet (6 mm in 3.6 m) are present. Use a straightedge placed perpendicular to the centerline to measure depressions and misalignment.  Straightedge requirements do not apply outside of area ground.

257.05 Method of Measurement. The Department will measure pavement grinding on existing pavements by the square yard (square meter) of pavement ground and accepted. The quantity of pavement grinding will be determined by multiplying the width specified on the plan by the total length of the finished pavement surface, excluding bridge decks, approach slabs or the 1.0 foot (0.3 m) adjacent to the existing pavement, pressure relief joints, approach slabs and other areas designated by the Engineer.

257.06 Basis of Payment.  Payment is full compensation for furnishing all labor, materials, tools, equipment and incidentals and for doing all work involved in grinding the existing surface, removing residue, cleaning the pavement, and testing with a profiler conforming to  the plans and specifications 

The Department will pay for accepted quantities at the contract price as follows:

Item           unit                                Description

257                    Square Yard                     Diamond grinding portland

                   (Square Meter)                   cement concrete pavement