This work consists of diamond
grinding a rigid concrete pavement, normally the full width of the lane, in
order to eliminate transverse cracking and transverse joint faulting. The work results in a longitudinal,
corduroy-type texture. If done properly,
the ride of the finished pavement surface will be improved and the skid
resistance enhanced.
Final acceptance of a diamond
ground pavement is done by surface measuring equipment, which is passed over
the completed pavement and measures the surface profile. This equipment is called a non-contact profilometer or a profiler.
Figure
257.A – Types of Diamond Grinding Equipment
Figure
257.B – Types of Diamond Grinding Equipment
Equipment requirements for
diamond grinding:
§ Must be a power driven, self-propelled machine,
specifically designed to smooth and texture Portland cement concrete pavement
with diamond blades or diamond impregnated cylinder rings.
§ Diamond blades or diamond impregnated cylinder rings
must be mounted on an arbor head that is a minimum of 3 feet long.
§ Must be capable of grinding the surface in the
longitudinal direction without causing spalling or other damage at cracks,
joints, and other locations.
§ Must be capable of correcting the pavement profile and
providing proper transverse cross-slope.
§ The effective wheelbase must be at least 12 feet (3.6
m): a set of pivoting tandem bogey
wheels at the front of the machine and at the rear. Wheels that travel and
track in the fresh cut pavement must be provided.
§ The center of the grinding head must not be further
than 3 feet (0.9 m) forward from the center of the back wheels.
§ Must be configured such that it does not encroach on
traffic movement outside of the work area in adjacent lanes
§ Must be designed to remove all grinding residue.
Grinding residue is not permitted to flow across lanes being used by the
traveling public.
Requirements for surface
measuring equipment (profiler):
§ A non-contact, surface measuring device, conforming to
Supplement
1058, along with ProVAL software, must be used to
measure an IRI.
§ All necessary supplies must be provided to fully
operate and graph the smoothness test results on the diamond ground pavement.
Contractors doing diamond
grinding work must use water trucks to provide water to the grinding heads of
each grinder in order to cool the diamond blades.
The plans will designate the
areas to be diamond ground. Bridge
decks, bridge approach slabs, and roadway shoulders are typically not diamond
ground unless indicated on the plans or required to provide drainage. Diamond grinding must eliminate crack or
joint faults while providing positive, lateral drainage by maintaining a
constant cross-slope between grinding limits in each lane. Adjacent ramp lane grinding must be
transitioned as required from the mainline edge to provide positive drainage
and an acceptable riding surface.
The diamond grinding
operation must result in pavement that conforms to the typical cross-section
and the requirements specified for the final surface finish. Faulting at joints and cracks must be
eliminated and the overall riding characteristics be restored within the limits
specified. To accomplish the smoothness
required, diamond grinding may not be required on 100 percent of the existing
pavement surface.
In faulted pavement, the rear
slab will be lower than the forward slab (in the direction of traffic), thus
creating a step or bump. Contractors will grind the pavement in the opposite
direction of normal traffic flow so the step is cut first and the remainder of
the slab can be feathered out. During initial grinding operations, the profiler
must 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,
the Contractor must run daily profiles of each day's grinding the following
work day.
All dust and residue
generated as a result of grinding must be immediately removed. Dust cannot be allowed to blow across traffic
lanes, into gutters, or into drainage structures.
The final surface finish
produced should be a longitudinal corduroy-type texture. The peaks of the ridges of this corduroy-type
texture are to be approximately 1/16 inch (1.5 mm) higher than the
grooves. There must be 53 to 57 evenly
spaced grooves per foot (174 to 187 per meter).
Figure
257.C – Surface Texture Left by Diamond Grinding
The pavement surface must be
tested by the Contractor with an approved profiler device that provides electronic
copies of the pavement profiles which are compatible with ProVAL
software. The Contractor must produce a
riding surface that does not exceed an IRI of 95
inches per mile or any localized surface deviations in excess of 0.4 inches in
25 feet.
The Engineer is to witness
testing of the pavement’s wheel paths.
Wheel paths are to be located every 3 feet (0.9 m); measured
transversely, inside all lane edges; and parallel to the centerline. The
profiler is to be maintained at the wheel path at all times when testing the
pavement.
Figure
257.D – Profile Measuring Device
Figure
257.E – Typical Profile Trace
The Contractor must regrind
any 0.10 mile section of pavement with an IRI greater
than 95 inches per mile.
The Contractor must provide
traffic control and survey stationing necessary for all profiling. Profile measuring equipment is to stop within
1 foot (0.3m) of any existing pavement not ground, any pressure relief joint or
any approach slab to a bridge.
Inspection should include
spot testing the pavement to verify that transverse joints and cracks are flush
with the adjacent pavement. If opposite
sides of a joint or crack are within 1/16 inch of each other, it is considered
flush. The cross-slope should be checked
with a 12 foot straightedge for deviations greater than 1/4 inch. Straightedge requirements do not apply to
areas that have not been ground.
Measure
pavement grinding 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 finished pavement surface measured in the field. This excludes bridge decks,
approach slabs, and other areas designated by the Engineer.
Payment is full compensation
for the furnishing of 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 that conforms to the plans
and specifications.
1. Check and document pavement grinding equipment prior
to use in order to assure compliance as to width of diamond grinding head,
number of grooves per foot, vacuum system, etc.
2. Check and document pavement smoothness testing equipment
for compliance. Obtain ODOT certification of the equipment from the Contractor.
3. Perform and document spot testing of ground pavement
for surface tolerances.
4. Obtain and document profiling test results.
5. Measure length of ground pavement and use the plan
width to calculate area for pay.
6. Document area calculations on CA-D-3A,
CA-D-3B, or other approved form.