Difference between revisions of "603 - Concrete Pavement Restoration"

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Type P-NC concrete utilizing a Type C or Type E (non-chloride) set accelerator is the preferred patching mixture for use on MDOT projects.  Use the manufacturer’s requirements for these set accelerators with the specified cement content to achieve a minimum flexural strength of 300 psi within the contract open-to-traffic time as determined for the project.
 
Type P-NC concrete utilizing a Type C or Type E (non-chloride) set accelerator is the preferred patching mixture for use on MDOT projects.  Use the manufacturer’s requirements for these set accelerators with the specified cement content to achieve a minimum flexural strength of 300 psi within the contract open-to-traffic time as determined for the project.
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====[[#Pavement Reinforcement|Pavement Reinforcement]]====
 
 
Pavement reinforcement is accepted for use by laboratory testing.  The reinforcement should be stored off the ground.  If contaminated, the reinforcement must be cleaned thoroughly before use.
 
 
 
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Repair isolated spalls of 10 in2 and greater per [http://mdotcf.state.mi.us/public/specbook/files/2012/602%20Conc%20Pavt%20Construction.pdf Standard Specification 602.03.P.1].  
 
Repair isolated spalls of 10 in2 and greater per [http://mdotcf.state.mi.us/public/specbook/files/2012/602%20Conc%20Pavt%20Construction.pdf Standard Specification 602.03.P.1].  
  
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All efforts should be made to not disturb the aggregate base material during removal of the existing concrete pavement and preparation of the site for concrete placement. If the base is disturbed, the contractor should be instructed to restore it to the required density and elevation. Depending on the severity of disturbance, this may require that the contractor install and compact additional base course aggregate. The department will not pay separately for this work required to correct these deficiencies as a result of the contractors operations.
  
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====[[#Intermediate Saw Cuts|Intermediate Saw Cuts]]====
 
====[[#Intermediate Saw Cuts|Intermediate Saw Cuts]]====
  
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Any low base caused by the Contractor’s operation will be filled with concrete at the Contractor’s expense.
 
Any low base caused by the Contractor’s operation will be filled with concrete at the Contractor’s expense.
 
 
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Transverse joints in pavement, shoulders and curb repairs will be the type shown on the plans.  Where existing curbs are to be left in place and expansion space is provided in the adjacent lane repair, an expansion joint (Esc) will be constructed in the curb by sawing and chipping out the existing concrete.  It is important that the width of the joint be equal to the width of the joint in the adjacent lane repair.  The Esc joint will align with the expansion joint in the repair.  The expansion joint filler will be shaped to fit the existing curb cross section.
 
Transverse joints in pavement, shoulders and curb repairs will be the type shown on the plans.  Where existing curbs are to be left in place and expansion space is provided in the adjacent lane repair, an expansion joint (Esc) will be constructed in the curb by sawing and chipping out the existing concrete.  It is important that the width of the joint be equal to the width of the joint in the adjacent lane repair.  The Esc joint will align with the expansion joint in the repair.  The expansion joint filler will be shaped to fit the existing curb cross section.
  
Expansion joint filler, for the Erg joints, will be 1 inch wide and extend the full depth of the patch minus 1-1/2 inch. Holes drilled into the joint filler must fit snugly around the dowel bars.  After October 15, the joint filler will extend the full depth of the patch until the joint is to be sealed.  At that time, the top 1-1/2 inch of the filler will be removed to form the joint reservoir for sealing.
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Expansion joint filler, for the Erg joints, will be 1 inch wide and extend the full depth of the patch minus 1-1/2 inch. Holes drilled into the joint filler must fit snugly around the dowel bars.  The joint filler will extend the full depth of the patch until the joint is to be sealed.  At that time, the top 1-1/2 inch of the filler will be removed to form the joint reservoir for sealing.
  
 
Care must be taken to ensure that the holes drilled into the existing slab for dowel bars are true to the horizontal and vertical planes of the roadway.  Dowels not in alignment will restrict the Crg or Erg joints from working properly.  Some adjustment may be needed in the drilling machine for proper alignment of the dowel bars, or to ensure that the holes miss the reinforcement steel in the existing pavement.
 
Care must be taken to ensure that the holes drilled into the existing slab for dowel bars are true to the horizontal and vertical planes of the roadway.  Dowels not in alignment will restrict the Crg or Erg joints from working properly.  Some adjustment may be needed in the drilling machine for proper alignment of the dowel bars, or to ensure that the holes miss the reinforcement steel in the existing pavement.
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Occasionally, the existing shoulder is in good shape, sound and flush with the edge of the pavement; and with care in removing the old pavement, it could be used as the side form.  If the Engineer feels that the existing shoulder can be left, the Contractor must saw between the shoulder and the old slab to eliminate any breakup of the shoulder during removal.  If there is any breakup, or after the removal of the slab the shoulder does not form a vertical, continuous edge to finish to, a side form will be required.
 
Occasionally, the existing shoulder is in good shape, sound and flush with the edge of the pavement; and with care in removing the old pavement, it could be used as the side form.  If the Engineer feels that the existing shoulder can be left, the Contractor must saw between the shoulder and the old slab to eliminate any breakup of the shoulder during removal.  If there is any breakup, or after the removal of the slab the shoulder does not form a vertical, continuous edge to finish to, a side form will be required.
 
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====[[#Mesh Reinforcement|Mesh Reinforcement]]====
 
 
All pavement repairs shall be of the reinforced type, except when indicated in the contract.  Refer to Standard Plan R-44 Series.  Pavement reinforcement for repairs 8 feet (2.5 m) or less has the larger diameter wire laying perpendicular to the centerline and repairs greater than 8 feet (2.5 m) should have the larger wire laying parallel to the centerline.  Bar chairs used to support the reinforcement are placed full widths of the repair and with no less than 3-1/2 foot (1,050 mm) maximum spacing.  Clean all reinforcement, if dirty.
 
  
 
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The concrete surface will be struck off twice with a vibratory screed.  For repairs 15 feet or less in length, the screed will be placed parallel to the centerline of the roadway.  For repairs more than 15 feet in length, the screed will be placed perpendicular to the centerline of the roadway.
 
The concrete surface will be struck off twice with a vibratory screed.  For repairs 15 feet or less in length, the screed will be placed parallel to the centerline of the roadway.  For repairs more than 15 feet in length, the screed will be placed perpendicular to the centerline of the roadway.
 
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====[[#Testing Requirements|Testing Requirements]]====
 
 
Slump, air content and temperature should be checked before the start of the pour and before any chloride has been added to the concrete to speed setting time.  The concrete mixture can be adjusted to a maximum slump of 3 inches (75 mm) and air content of 5.5 percent ± 1.5 percent.  The addition of chloride will increase the slump and air content slightly.  No additional tempering of the concrete will be allowed, with the exception that 2 gallons (7 L) of water may be used to wash any particles of chloride from the mixer opening and fins.
 
 
An immersion-type vibrator is required for consolidation of the concrete, with special attention given to the area around the dowel bars.  The vibrator should be placed in the concrete in a vertical position for best consolidation.
 
 
The concrete surface will be struck off twice with a vibratory screed.  For repairs 15 feet (4m) or less in length, the screed will be placed parallel to the centerline of the roadway.  For repairs more than 15 feet (4 m) in length, the screed will be placed perpendicular to the centerline of the roadway.
 
  
 
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While the concrete is still plastic, the surface will be straightedged as follows.
 
While the concrete is still plastic, the surface will be straightedged as follows.
  
For repairs 10 feet (3 m) or less in length, the straightedging will be done by placing the straightedge parallel to the pavement centerline with the ends resting on the existing pavement and drawing the straightedge across the repair.  The straightedging of 6 feet (2.0 m), 8 feet (2.5 m), and 10 feet (3.0 m) repairs will be accomplished by use of a straightedge not exceeding the length of the repair by more than 6 inches (150 mm).  The straightedge will be in contact with the existing pavement while drawing it across the repair.  Any high or low spots exceeding 1/8 inch (3 mm) will be corrected.  Recheck after corrections are made.
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For repairs 10 feet or less in length, the straightedging will be done by placing the straightedge parallel to the pavement centerline with the ends resting on the existing pavement and drawing the straightedge across the repair.  The straightedging of 6 feet, 8 feet, and 10 feet repairs will be accomplished by use of a straightedge not exceeding the length of the repair by more than 6 inches.  The straightedge will be in contact with the existing pavement while drawing it across the repair.  Any high or low spots exceeding 1/8 inch will be corrected.  Recheck after corrections are made.
  
For repairs more than 10 feet (3 m) in length, the first and last measurement will be made with approximately half the straightedge resting on the existing pavement; and the second and next to last measurement will each be made with 2 inches (50 mm) to 3 inches (75 mm) of the straightedge resting on the existing pavement.  Any irregularities will be treated as above.
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For repairs more than 10 feet in length, the first and last measurement will be made with approximately half the straightedge resting on the existing pavement; and the second and next to last measurement will each be made with 2 inches to 3 inches of the straightedge resting on the existing pavement.  Any irregularities will be treated as above.
  
 
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====[[#Finishing Patches|Finishing Patches]]====
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====[[#Texturing|Texturing]]====
  
The joint groove of the Erg joints will be saw cut 1 inch (25 mm) wide and 1-1/2 inch (38 mm) deep.  The joint groove for the Crg joints will be saw cut 1/2 inch (12.5 mm) wide and 3/4 inch (18 mm) deep.  Both types of joint groves shall extend the full width of the patch.  The Contractor may saw an initial relief cut or saw to the plan dimensions as soon as the concrete has hardened sufficiently so that no excess raveling or spalling occurs.  All edging will be done with a 1/8 inch (3 mm) to 1/4 inch (6 mm) radius along the entire perimeter before texturing.  The surface of the repair will be textured perpendicular to the pavement center and should have a texture similar to the adjacent pavement.
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The surface of the repair should have a texture similar to the adjacent pavement.
  
 
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====[[#Curing Patches|Curing Patches]]====
 
====[[#Curing Patches|Curing Patches]]====
  
Curing compound will be applied immediately after all free water has evaporated from the surface.  White membrane curing compound will be used, unless the repair is to be overlaid with HMA, and then transparent curing compound will be used.  Either type of curing compound will be applied at a rate of not less than 1 gallon per 20 yd<sup>2</sup> (1 liter per 5 m<sup>2</sup>).
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Curing compound will be applied immediately after all free water has evaporated from the surface.  White membrane curing compound will be used, unless the repair is to be overlaid with HMA, and then transparent curing compound will be used.  Either type of curing compound will be applied in 2 coats at a rate of not less than 1 gallon per 25 yd² for each coat.  
  
Insulated blankets having a minimum thickness of 2 inches (50 mm) will be placed over the repaired area when the curing compound has been applied and when the air temperature during the curing period falls below 65 °F (18 °C) for Type P-MS and P-NC concrete repairs.  Edges and seams in the blanket will be secured to prevent loss of heat.  Test beams, for open to traffic strengths, will be cured the same as the repair.  Insulated blankets may be removed when the concrete has attained a flexural strength of 500 psi (3.5 MPa) for Type P-MS and P-NC concrete.
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Insulated blankets having a minimum thickness of 2 inches will be placed over the repaired area when the curing compound has been applied and when the air temperature during the curing period falls below 50°F for all concrete repairs.  Edges and seams in the blanket will be secured to prevent loss of heat.  Test beams, for open to traffic strengths, will be cured the same as the repair.  Insulated blankets may be removed when the concrete has attained a flexural strength of 300 psi for P-NC concrete and 550 psi for P1 and P1M concrete.
  
 
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===[[#Strength Requirements|Strength Requirements]]===
 
===[[#Strength Requirements|Strength Requirements]]===
  
The concrete repairs may be opened to traffic when the concrete has attained a flexural strength of 500 psi (3.5 MPa) for repairs constructed with Type P-MS or P-NC concrete, and 550 psi (3.8 MPa) for repairs constructed with Grade HE of Grade PI concrete. Traffic may be allowed over the repair before cleaning and sealing the joints.
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The concrete repairs may be opened to traffic when the concrete has attained a flexural strength of 300 psi for repairs constructed with Type P-NC concrete, and 550 psi for repairs constructed with Grade P1 or P1M concrete. Traffic may be allowed over the repair before cleaning and sealing the joints.
  
Strength test beams, for acceptance and open to traffic, should be made on the job and cured the same as the repairs.  This includes being placed under the blankets if blankets are used as an aid to curing.
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Strength test beams, for acceptance and open to traffic, should be made on the job and cured the same as the repairs.  This includes being placed under the blankets if blankets are used as an aid to curing. Beams should be cast at the start of the pour and broken at different times to establish the length of curing time necessary to reach the required strength.  Increasing or decreasing the time between making and testing the beams will give the inspector a good indication of the time needed to achieve the required strength.
  
Beams should be cast at the start of the pour and broken at different times to establish the length of curing time necessary to reach the required strength.  Increasing or decreasing the time between making and testing the beams will give the inspector a good indication of the time needed to achieve the required strength.
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The flexural strength is calculated using the following equation per ASTM C293 – Standard Test Method for Flexural Strength of Concrete (Using Simple Beam With Center Point Loading):
  
When using a high early (HE) concrete mixture, beams can be tested at the end of 72 hours and checked against the strength specification.  Medium-set (P-MS) or non-chloride (P-NC) concrete should meet specified strengths within 24 hours curing time up to ± 8 hours.  The first beam would be tested in ± 4 hours; if it does not meet the specified strength, a second beam would be cured additional time, ± 5 hours, and likewise for a third beam.
 
  
If a Swiss hammer is going to be used as an indicator of in-place strength of the patch, before the first beam is unmolded and tested, take 16 readings with the Swiss hammer for calibration.
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[[File:EQ603-01.png|300px|thumbnail|center|Flexural Strength of Concrete (Using Simple Beam With Center Point Loading):]]
  
When the specified strengths are achieved, the inspector should have the approximate cure time and a Swiss hammer number to be used on the repairs for opening to traffic.
+
Where:
 +
 +
:R = modulus of rupture or flexural strength in psi
 +
:P = maximum applied load in lbs
 +
:L = span length in inches
 +
:b = average specimen width in inches
 +
:d = average specimen depth in inches
  
The Swiss hammer should be recalibrated with a new set of beams weekly, or any time the mix is changed.
 
  
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Calculate the average specimen width (b) and depth (d) by measuring the width and depth at each end of the beam and taking the average of those measurements.
  
===[[#Sealing Joints and Opening to Traffic|Sealing Joints and Opening to Traffic]]===
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[[File:FIG603-01.png|600px|thumbnail|center|Beam Measurements]]
  
Longitudinal bulkhead joints, joints in base course repairs, joints in repairs constructed in preparation for HMA overlays and Trg joints need not be constructed with joint reservoirs and need not be sealed.  All other joints and all saw cuts that were made in pavements, shoulders or gutters over cutting will be cleaned and then sealed with hot poured sealant.
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When using a concrete beam tester with center point loading and a 16 inch span length (L),  the flexural strength equation above may be simplified using the modulus of rupture factors in table 1. The simplified equation is as follows:
  
All concrete remaining on top of the expansion joint filler will be removed before abrasive blast cleaning.  All joints to be sealed will be abrasive blast cleaned and then cleaned with a jet of compressed air, free of oil and water, having a minimum pressure of 90 psi (620 kPa), immediately before sealing.  A bond breaker tape will be placed in the bottom of the Crg joint groove after the final cleaning and before sealing.
 
  
Before opening to traffic, HMA shoulders will be restored to the existing line and grade using a plant-mixed HMA mixture, as directed by the Engineer.  Cold patch mixtures used for temporary patching will be replaced with plant-mixed HMA mixtures, unless shoulder reconstruction is a part of the project and has not been completed.  The HMA mixture will be compacted by mechanical or hand methods suitable for the size hole being filled.  HMA plant mixtures will be placed at a temperature suitable for compaction.  Concrete shoulders will be constructed as shown on the plans.  Materials removed from the shoulder will be disposed of by the Contractor.
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[[File:EQ 603-02.png|300px|thumbnail|center|Simplified Center Point Flexural Strength Equation ]]
  
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Where:
 +
:F = modulus of rupture factor in in²
  
===[[#Diamond Grinding|Diamond Grinding]]===
 
  
Diamond grinding is used to restore the surface longitudinal profile and improved ride quality of a PCC pavement.  And many times is done in conjunction with other PCC pavement restoration treatments.  Grinding is performed on the roadbed in the longitudinal direction for the entire lane width as specified on the plans.
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[[File:Table603-01.png|600px|thumbnail|center|Table 1: Modulus of Rupture Factors (F)]]
 
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A self-propelled grinding machine uses diamond saw blades that are gang-mounted on a cutting head to profile the pavement. The machine used can significantly affect the efficiency and rate of grinding.  The three most important machine related factors in the diamond grinding process is the weight of the machine, the horse power available to the grinding head, and the grinding head itself.  The degree of hardness of the aggregate in the PCC will also affect time required to complete the project.
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Usually 54 to 59 blades per foot are required to produce a level surface with a corduroy-type texture. The peaks and ridges of the corduroy should average 1/8 inch.  If the area ground results in a polished surface or a surface with fins more, that 1/4 inch high, the spacing of the blades should be adjusted.  Grinding equipment that causes ravels, aggregate fractures, spalls or distress of the transverse or longitudinal joint should not be permitted.
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The transition between ground and unground pavements should be gradual and result in an acceptable ride quality.  Care should be taken to assure that positive drainage is maintained at all times in the transitions between the mainline edge and auxiliary lanes, ramp lanes and shoulders.
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The grinding operation produces a slurry of ground concrete and water to cool the blades.  The slurry is chemically inert and can be discharged onto the shoulder area or vacuumed into trucks depending on the location of the project.  Prior to beginning the grinding operation, the Engineer will approve the disposal method.  At no time should slurry be discharged within 100 feet of any natural stream or lake or within 5 feet of a water-filled ditch.  Nor should it be allowed to enter a closed drain system.  Check the project proposal for allowed discharge areas.
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Random samples of the slurry should be taken for chemical testing of the grinding residue and cooling water.
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The inspector should make the following checks during the diamond grinding operation:
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* Texture
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* Overlap of successive passes of grinding head
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* Blade Spalling
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* Pattern
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* Aggregate hardness
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* Sand Patch test to verify macro texture depth
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===[[#Dowel Bar Retrofit (DBR)|Dowel Bar Retrofit (DBR)]]===
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===[[#Sawing and Sealing Joints|Sawing and Sealing Joints]]===
 
+
Dowel bar retrofit commonly referred to as DBR is a repair procedure typically used on concrete pavement that exhibits intermittent transverse cracking.  This repair is typically used to restore load transfer at the location of the crack.
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+
Dowel bar retrofits are not appropriate for all pavements that have transverse cracking.  Good candidate concrete pavements that should be retrofit have little or no spalling at the surface of the crack to be repaired.  The crack should also be level, not faulted, from one side to the other.  Attempting to DBR a pavement that exhibits spalled or faulted joints will result in failure of the DBR.  Contact the Pavement Structures Unit at C&T Division for questions regarding the appropriate use of DBR.
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+
See various descriptions below for examples of pavements that are good candidates for a DBR.
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====[[#Slot Cutting|Slot Cutting]]====
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====[[#Sawing Joints|Sawing Joints]]====
  
* Slots shall be cut using a diamond-bladed saw machine.
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The joint reservoir of the Erg joints will be saw cut 1 inch wide and 1-1/2 inch deep. The joint reservoir for the Crg joints will be saw cut 1/2 inch wide and 3/4 inch deep. Both types of joint reservoirs shall extend the full width of the patch. The Contractor may saw an initial relief cut or saw to the plan dimensions as soon as the concrete has hardened sufficiently so that no excess raveling or spalling occurs.  All edging will be done with a 1/8 inch to 1/4 inch radius along the entire perimeter before texturing.
* The machine shall typically be capable of cutting a minimum of three slots simultaneously that are centered over the crack.
+
* Slots shall also be centered over the crack or as directed by the Engineer.
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* If the crack wanders, the slots shall be cut to have a specified minimum overlap of the dowel bar on each side of the crack according to the specification.
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* The Contractor shall visibly mark the cracks along their length so that the slot cutter can see them to properly place the slots.
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====[[#Removal of Concrete|Removal of Concrete]]====
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====[[#Cleaning Joints|Cleaning Joints]]====
  
* The concrete remaining in the slots after sawing shall be removed with lightweight chipping hammers no greater than 30 lbs.
+
All concrete remaining on top of the expansion joint filler will be removed before abrasive blast cleaning. All joints to be sealed will be abrasive blast cleaned and then cleaned with a jet of compressed air, free of oil and water, having a minimum pressure of 90 psi, immediately before sealing.
* The Contractor must provide manufacturer specifications to verify the capacity of the chipping hammers is no greater than 30 lbs.
+
* Concrete shall be removed in such a manner so as to prevent any pavement fractures caused by the removal operations.
+
* If the Contractor is allowed to use chipping hammers larger than 30 lbs, micro cracking of the remaining concrete will occur.
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====[[#Spall Repair|Spall Repair]]====
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====[[#Sealing Joints|Sealing Joints]]====
  
* Minor spalls, intermediate and major spalls shall be repaired using the patching material used to backfill the slot in accordance with [http://mdotcf.state.mi.us/public/specbook/files/2012/603%20Conc%20Pavt%20Restoration.pdf Section 6] of the Standard Specifications for Construction.
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All joints and all saw cuts that were made in pavements, shoulders or gutters over cutting will be cleaned and then sealed. Longitudinal bulkhead joints, joints in base course repairs, joints in repairs constructed in preparation for HMA overlays and Trg joints will not be constructed with joint reservoirs and need not be sealed. A backer rod will be placed in the bottom of Cp and Crg joint reservoirs after the final cleaning and before sealing with hot-poured sealant. Seal the joint reservoir to no greater than 1/8 inch (after cooling) below the concrete pavement surface.
  
 
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====[[#Slot Cleaning|Slot Cleaning]]====
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====[[#HMA Shoulder Replacement|HMA Shoulder Replacement]]====
  
* Any loose concrete shall be vacuumed or removed from the slot and all surfaces shall be dry, abrasive blast cleaned.
+
Before opening to traffic, HMA shoulders will be restored to the existing line and grade using a plant-mixed HMA mixture, as directed by the Engineer.  Cold patch mixtures used for temporary patching will be replaced with plant-mixed HMA mixtures, unless shoulder reconstruction is a part of the project and has not been completed.  The HMA mixture will be compacted by mechanical or hand methods suitable for the size hole being filled.  HMA plant mixtures will be placed at a temperature suitable for compaction.  Concrete shoulders will be constructed as shown on the plans.  Materials removed from the shoulder will be disposed of by the Contractor.
* Any exposed steel shall be blast cleaned to remove any rust or laitance.
+
* Immediately prior to placement of the dowels and patching material, the slots shall be final cleaned with moisture-free, oil-free compressed air having a minimum pressure of 90 psi.
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====[[#Dowel Bar Placement|Dowel Bar Placement]]====
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===[[#Diamond Grinding and Longitudinal Grooving|Diamond Grinding and Longitudinal Grooving]]===
  
* After final cleaning, the crack shall be sealed with a bond breaker tape or joint sealant to prevent the patching material from entering the crack.
+
Diamond grinding is used to restore the surface longitudinal profile and improved ride quality of a PCC pavement. And many times is done in conjunction with other PCC pavement restoration treatments.  Grinding is performed on the roadbed in the longitudinal direction for the entire lane width as specified on the plans.  
* When aligned correctly, dowels shall be true to the pavement surface and parallel to the pavement centerline.
+
* Bond release agents shall be applied over the entire dowel bar prior to placing the dowel bar into the slots.
+
* Any bond release agent spilled on any slot surface shall be immediately removed and the slot surface cleaned.
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Usually 54 to 59 blades per foot are required to produce a level surface with a corduroy-type texture. The peaks and ridges of the corduroy should average 1/8 inch.  If the area ground results in a surface with fins more than 1/4 inch high, the spacing of the blades should be adjusted.  Grinding equipment that causes ravels, aggregate fractures, spalls or distress of the transverse or longitudinal joint should not be permitted.
  
====[[#Patching|Patching]]====
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The transition between ground and unground pavements should be gradual and result in an acceptable ride quality.  Care should be taken to assure that positive drainage is maintained at all times in the transitions between the mainline edge and auxiliary lanes, ramp lanes and shoulders.
  
* The patching material shall be mixed with a portable or mobile mixer.
+
Groove pavement 0.12 ± 0.03 inches wide by 0.16 ± 0.03 inches in depth, with a land area between the grooves of 0.75 ± 0.05 inches.  
* The patching material shall then be consolidated using a hand-held vibrator or as recommended by the manufacturer.
+
* The surface of the patch shall be finished flush with the surrounding concrete and cured according to manufacturer’s recommendations.
+
* The surface must be finished flush with the surrounding surface even if diamond-grinding of the concrete surface is to occur afterward.
+
* The slot walls and bottom must be dry before placement of the patching material, unless otherwise recommended by the manufacturer.
+
* The patching material can be tested as necessary to verify that the mixture meets the specification.
+
  
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When the Special Provision for Pavement Ride Quality is included in the contract, the Engineer will submit the Ride Quality Plan to the pavement evaluation group at Construction Field Services for concurrent review and to coordinate ride quality acceptance testing.
 
+
====[[#Opening to Traffic|Opening to Traffic]]====
+
 
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* The patching material shall be cured for the minimum time required by the contract specification before placing any vehicle loads on the repair.
+
  
 
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==[[#MEASUREMENT AND PAYMENT|MEASUREMENT AND PAYMENT]]==
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====[[#Control and Disposal of Grinding Residue|Control and Disposal of Grinding Residue]]====
  
 +
The requirements for disposing of grinding residue are detailed in the [http://mdotcf.state.mi.us/public/specprov/#6f095c01-0e9f-4b4a-82fa-8a26a4efb2c6 Special Provision for Managing Diamond Grinding Slurry from Ride Quality Concrete]. The grinding operation produces slurry of ground concrete and water to cool the blades. Prior to beginning the grinding operation, the Engineer will approve the disposal method. At no time should slurry be discharged within 100 feet of any natural stream or lake or within 5 feet of a water-filled ditch. Nor should it be allowed to enter a closed drain system. Check the project proposal for allowed discharge areas.
  
===[[#Sand Patch Test ASTM 965-96E|Sand Patch Test ASTM 965-96E]]===
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Random samples of the slurry should be taken for chemical testing of the grinding residue and cooling water.
  
Measuring Pavement Macro Texture Depth Procedure as follows:
+
The inspector should make the following checks during the diamond grinding operation:
  
* Select a dry homogeneous area that contains no unique features.
+
* Texture
* Clean surface using a clean wire brush.
+
* Overlap of successive passes of grinding head
* Position a portable wind screen around the surface.
+
* Blade Spalling
* Fill cylinder of known volume with dry silica sand.  Sand will be furnished with the kit.  (100% passing the #60 sieve, but 100% retained on the #80 sieve).
+
* Pattern
* Gently tap base of cylinder several times to fill voids and top off cylinder with more material.
+
* Aggregate hardness
* Pour measured volume of sand on cleaned surface protected from winds.
+
* Sand Patch test to verify macro texture depth
* Carefully spread material in a circular motion with hockey puck.
+
* Measure and record the diameter of the circular area covered by the sand at four equally spaced locations around the circumference.  Compute and record the following:
+
 
+
Average of the four depth measurements (ave. D)
+
 
+
(ave.  D)<sup>2</sup>
+
 
+
Mean texture depth, in = 4.1 (ave.D)<sup>2</sup>
+
 
+
'''Note:'''    The constant is derived for use with a measuring container having a calibrated volume of 3.2 cubic inches.
+
  
 
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===[[#Capital Preventative Maintenance - Performance Warranties|Capital Preventative Maintenance - Performance Warranties]]===
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==[[#MEASUREMENT AND PAYMENT|MEASUREMENT AND PAYMENT]]==
 
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Special provisions currently govern requirements for performance warranties on all Capital Preventive Maintenance projects.  These special provisions will be in the project proposal.  Copies of all forms referenced in this section can be found in the Capital Preventive Maintenance Program Manual.
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'''Prior to award''' of the contract, the Contractor must supply the Department a warranty, performance and lien bond.  The warranty bonds furnished by the Contractor are in an amount equal to 100% of the contract total.  In addition to those bonds, the Contractor must also complete a warranty form.  The bonds and warranty form are retained in the Contract Section’s files.
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'''During construction''', the Department is responsible for inspection of the job to assure the Contractor is using the specified materials and that their construction and traffic control methods are meeting the contract requirements.  The Contractor’s Daily Report is a generic report that should be used on all Preventive Maintenance warranty projects to document required information.  This report supplements the daily documentation required, per specification, for each specific treatment.  The Contractor will complete the form on a daily basis in addition to all other documentation required by the specifications.  The intent of the form is to aid the project office in tracking the project status and pay items.
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'''After completion of construction''' of the warrantied work, the Department and the Contractor will review the work for compliance with the contract.  If the work is determined by the Department to not be in compliance, the Contractor shall be required to repair the defects.  When the work is in compliance, a form entitled “Initial Acceptance for Preventive Maintenance Warranty” form will be completed by the Department and the Contractor to document the acceptance date of construction.
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'''The Initial acceptance form''' is used to document the starting date of the warranty period, upon departmental acceptance of the surface treatment.  This form may be used for the entire project or for portions of a project.  The Project Engineer and the Contractor will review the surface treatment to confirm that it meets the project specifications.  Once both agree that the surface treatment is in compliance with the project specifications, the form is completed and signed by both parties.  A copy is then sent to the Surety Company by the Contractor.  A copy of the form should be retained in the project office’s project file and the original sent to Financial Services - Payments.
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'''During the warranty period''', the Department is responsible for monitoring the preventive maintenance surface treatment for compliance with the warranty performance criteria.  The Project Engineer should use the Field Evaluation of Warranty Performance form to document the condition of the surface treatment during the warranty period as related to the warranty performance criteria.
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If the surface treatment exceeds the threshold limits, as defined in the project warranty specification, the Department will notify the Contractor, in writing, of the required warranty work.  The Department will provide the Contractor all written reports of the surface treatment’s condition relating to the warranty performance criteria.
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If the Contractor disagrees with the findings of the Department, a Conflict Resolution Team (CRT) will be established.  The CRT will consist of a five-member team.  The Department and the Contractor will each select two representatives for the CRT.  A third Party Member will be mutually selected by the Department and the Contractor to complete the CRT.  See “Conflict Resolution Process” in the [http://www.michigan.gov/documents/mdot/MDOT_CapitalPreventiveMaintenanceManual_322973_7.pdf Capital Preventive Maintenance Program Manual] for detailed information on this process.
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'''Refer to the special provisions and the Guidelines for Administering Warranties on Road and Bridge Construction Contracts for more information on warranty rights and responsibilities.'''
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'''If warranty work is required''', the Contractor must supply a supplemental performance and lien bond to the Project Engineer for all warranty work identified that is consist with the warranty specification performance criteria.  The supplemental performance and lien bonds should be retained in the project office’s project file.  In addition to supplemental bonds, the Contractor is required to furnish new insurance documentation, to the Project Engineer, for the warranty work in accordance with subsection [http://mdotcf.state.mi.us/public/specbook/files/2012/107%20Legal%20Rel,%20Resp%20to%20Public.pdf 107.10] of the Standard Specifications for Construction.  The new insurance coverage shall be consistent with that of the original contract.  All insurance documentation should be retained in the project office’s project file.
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[[Category:Construction Manual]]
 
[[Category:Construction Manual]]
[[Category:Division 6]]
 

Latest revision as of 11:14, 19 April 2017

603
Concrete Pavement Restoration
2012 STANDARD SPECIFICATIONS FOR CONSTRUCTION - SECTION 603


Contents

[edit] GENERAL

This work consists of repairing portions of a concrete pavement with Portland cement concrete and the type of joints specified. Pavement includes mainline pavement, base course or concrete shoulders.


Joint Type
Description
Trg

Tied repair grouted

Crg

Contraction repair grouted

Erg

Expansion repair grouted

Esc

Expansion curb joint

Joint, Tied, Special

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[edit] Patching

Before patching begins, the Engineer and the inspector should review the following items:

  • Special Provisions
  • Supplemental Specifications
  • Project plans and drawings
  • Standard Plans
  • Standard Specifications
  • Concrete pavement condition survey or project log

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[edit] Inspection During Patching

  • Layout patches
  • Removals
  • Various joints
  • Placing and finishing concrete
  • Sealing joints
  • Shoulder or curb replacement


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[edit] MATERIALS

Before patching begins, the inspector should verify that proper concrete mix design charts are being used and that all materials to be incorporated in the patches have been tested and accepted.

Concrete for patching must be produced by a NRMCA-certified plant, or have been accepted for use by the Region materials personnel as a noncertified, automated or manual plant.

The grade of concrete required is based on the time allowed between the casting of the repair and the intended opening of the repair to traffic.

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[edit] Type or Grade of Concrete

Unless modified by special provision the grade of concrete required will be as follows.

From Casting to Intended
Opening to Traffic
Grade of Concrete
< 72 hours
Type P-NC Concrete
≥ 3 days
Grade Grade P1, P1M Concrete

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[edit] Type P-NC (non-chloride)

Type P-NC concrete utilizing a Type C or Type E (non-chloride) set accelerator is the preferred patching mixture for use on MDOT projects. Use the manufacturer’s requirements for these set accelerators with the specified cement content to achieve a minimum flexural strength of 300 psi within the contract open-to-traffic time as determined for the project.

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[edit] Load Transfer Assemblies

Load transfer assemblies for contraction (Cp) and expansion (E2) joints will be according to the Standard Plan R-39 and R-40 Series.

After the assemblies arrive on the project site, they must be visually inspected for the following items.

  • Broken or missing welds or bent assemblies
  • Proper height of dowels and joint filler for the pavement being repaired
  • Holes in joint filler must match the dowel size with no space for leakage
  • Use of approved expansion caps and their proper installation
  • Verify tie wire of maximum nominal diameter of 0.177 in.

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[edit] Dowel Bars and Lane Tie Bars

Deformed dowel bars for Trg joints will be epoxy coated, #9 x 18 inches long. Dowel bars for Crg and Erg joints will be epoxy coated, #10 x 18 inches long. Lane tie bars will be straight #5 deformed bars x 18 inches long.

The material used to secure in the dowel bars must be from the Qualified Products List.

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[edit] Bond Breakers

The bond breaker used on the dowel bar assembly must be from the Qualified Products List. The bond breaker used for individually placed dowel bars may also be RC 250.

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[edit] CONSTRUCTION

[edit] Patch Layout

The location of repairs will be listed on a log in the proposal, on the plans, or in the pavement condition survey log.

Locate, number and record, for future documentation, the size and type of joint or the repairs to be removed. The minimum concrete pavement patch length is 4 feet. However, additional patch length is recommended in faulted pavement scenarios. If additional length is needed for proper repair, the inspector should inform the Contractor of the new size after checking with the Engineer.

The Contractor will lay out the patch at right angles to the centerline before sawing starts. Check the Standard Plan R-44 Series for the sawing diagram.

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[edit] Removing Old Concrete

Before removal, the concrete will be sawed full depth according to the details shown on the plans or in the proposal. This must be done with multiple passes within the same 12 hour period or in one pass. Transverse saw cuts will be made in a straight line at right angles to the pavement’s centerline, within a tolerance of 1 inch per lane width. The longitudinal joint adjacent to other lanes, ramps, shoulders, curb and gutter will be sawed full depth.

The pavement surface will be flushed immediately after the sawing operation to remove all slurry. Remove concrete pavement between narrowly spaced sawcuts at the end of the slab with air hammers and hand tools to minimize spalling.

Patches less than 100 feet in length will be removed without disturbing the subbase/subgrade according to subsection 603.03 of the Standard Specifications for Construction.

Repair isolated spalls of 10 in2 and greater per Standard Specification 602.03.P.1.

All efforts should be made to not disturb the aggregate base material during removal of the existing concrete pavement and preparation of the site for concrete placement. If the base is disturbed, the contractor should be instructed to restore it to the required density and elevation. Depending on the severity of disturbance, this may require that the contractor install and compact additional base course aggregate. The department will not pay separately for this work required to correct these deficiencies as a result of the contractors operations.

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[edit] Intermediate Saw Cuts

Intermediate saw cuts, used to reduce slab size more than 6 feet for hauling, should be recorded for payment purposes. Curb sections removed with a patch will be recast with the pour and paid as concrete pavement repair.

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[edit] Aggregate Base

After removing the old slab, cleaning up loose material should be done by hand so as not to disturb the existing base. If the existing base was more than 2 inches low before removal, corrections can be made by adding aggregate base material and compacting.

If the existing base is less than 2 inches low, additional aggregate base material is not necessary, and the void will be filled with concrete included in the concrete patching pay item.

Any low base caused by the Contractor’s operation will be filled with concrete at the Contractor’s expense.

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[edit] Joints

According to Standard Plan R-44 Series, place Contraction Joint (Crg) or Expansion Joint (Erg) at transverse joints where the repair meets existing pavement. Tied Joint (Trg) may be permitted as needed.

The same type of joint should be used in the second and third pours, if needed.

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[edit] Expansion Joints (Erg)

Care should be taken to place enough expansion joints (Erg) for the pavement being repaired. Expansion requirements will vary based on condition of existing pavement and temperature at time of repair.

Erg joints should be used only if the repair extends across the entire width of the roadway. If only one lane is being repaired, every effort should be made to match the joint in the original slab.

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[edit] Transverse Joints

Transverse joints in pavement, shoulders and curb repairs will be the type shown on the plans. Where existing curbs are to be left in place and expansion space is provided in the adjacent lane repair, an expansion joint (Esc) will be constructed in the curb by sawing and chipping out the existing concrete. It is important that the width of the joint be equal to the width of the joint in the adjacent lane repair. The Esc joint will align with the expansion joint in the repair. The expansion joint filler will be shaped to fit the existing curb cross section.

Expansion joint filler, for the Erg joints, will be 1 inch wide and extend the full depth of the patch minus 1-1/2 inch. Holes drilled into the joint filler must fit snugly around the dowel bars. The joint filler will extend the full depth of the patch until the joint is to be sealed. At that time, the top 1-1/2 inch of the filler will be removed to form the joint reservoir for sealing.

Care must be taken to ensure that the holes drilled into the existing slab for dowel bars are true to the horizontal and vertical planes of the roadway. Dowels not in alignment will restrict the Crg or Erg joints from working properly. Some adjustment may be needed in the drilling machine for proper alignment of the dowel bars, or to ensure that the holes miss the reinforcement steel in the existing pavement.

For long one lane repairs spanning an existing joint, Cp or E2 joints should be constructed according to the Standard Plan R-44 Series.

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[edit] Longitudinal Joints

Where more than one lane is cast in a single pour, longitudinal joints will be constructed in line with existing longitudinal joints and to a depth of one-third the thickness of the pavement, either by sawing or by forming. Lane ties will be according to the Standard Plan R-44 Series.

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[edit] Dowels

It is important that all holes are cleaned of the drilling residue by using an air wand fully inserted into the hole. Enough grout is placed into the hole to completely fill the space between the bar and the hole. The bars will be inserted slowly with a twisting motion until they are seated properly. Wipe the excess grout off the face of the existing pavement.

The portion of the dowel bars for Crg and Erg joints that extend beyond the face of the existing pavement will be uniformly coated with an approved bond breaker. An approved expansion cap will then be properly installed on each dowel for Erg joints, making sure the cap is not pushed past the 1 inch stops. Deformed bars used in Trg joints and lane ties need not be coated with a bond breaker.

Prior to concrete placement, the inspector should confirm that the epoxy on grout has properly set. This is usually accomplished by obtaining a properly mixed sample, observing the set and the time required to reach set.

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[edit] Forms

Lumber used for forms on the shoulder side of the repair will be nominal 2 inch width and full depth and in one piece for repairs 10 feet or less in length. For repairs greater than 10 feet, wood or metal forms can be used since they can be locked or spliced to provide a continuous form. Form material between lanes can be nominal 1 inch lumber. Care should be taken to reestablish the grade between patch edges for a good ride.

Occasionally, the existing shoulder is in good shape, sound and flush with the edge of the pavement; and with care in removing the old pavement, it could be used as the side form. If the Engineer feels that the existing shoulder can be left, the Contractor must saw between the shoulder and the old slab to eliminate any breakup of the shoulder during removal. If there is any breakup, or after the removal of the slab the shoulder does not form a vertical, continuous edge to finish to, a side form will be required.

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[edit] Placing and Finishing Concrete

Concrete will be placed usually the same day the existing concrete is removed and cast full depth in a single pour.

Immediately before placement of concrete, the existing pavement faces and the base will be dampened. Standing water must be removed before concrete placement.

For repairs more than 15 feet in length, the repair area in adjacent lanes, ramps, or shoulders will be cast separately.

The concrete should be struck off using two passes with a vibrating screed or roller screed. Check the surface with a straightedge. Care in edging, especially along the joint edges, will reduce spalling when forming materials are removed. Any spalling of the joint must be repaired.

For repairs 15 feet or less in length, the screed will be placed parallel to the centerline of the roadway. More than 15 feet in length, the screed will be placed perpendicular to the centerline of the roadway.

An immersion-type vibrator is required for consolidation of the concrete, with special attention given to the area around the dowel bars. The vibrator should be placed in the concrete in a vertical position for best consolidation.

The concrete surface will be struck off twice with a vibratory screed. For repairs 15 feet or less in length, the screed will be placed parallel to the centerline of the roadway. For repairs more than 15 feet in length, the screed will be placed perpendicular to the centerline of the roadway.

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[edit] Straightedging

While the concrete is still plastic, the surface will be straightedged as follows.

For repairs 10 feet or less in length, the straightedging will be done by placing the straightedge parallel to the pavement centerline with the ends resting on the existing pavement and drawing the straightedge across the repair. The straightedging of 6 feet, 8 feet, and 10 feet repairs will be accomplished by use of a straightedge not exceeding the length of the repair by more than 6 inches. The straightedge will be in contact with the existing pavement while drawing it across the repair. Any high or low spots exceeding 1/8 inch will be corrected. Recheck after corrections are made.

For repairs more than 10 feet in length, the first and last measurement will be made with approximately half the straightedge resting on the existing pavement; and the second and next to last measurement will each be made with 2 inches to 3 inches of the straightedge resting on the existing pavement. Any irregularities will be treated as above.

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[edit] Texturing

The surface of the repair should have a texture similar to the adjacent pavement.

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[edit] Stenciling

The month and the year will be stenciled in each repair. If the existing stationing is removed within the patch area, the station will be restenciled in the repair at the appropriate location. If a Swiss hammer is being used for strength testing, a small area in each corner should be troweled smooth.

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[edit] Curing Patches

Curing compound will be applied immediately after all free water has evaporated from the surface. White membrane curing compound will be used, unless the repair is to be overlaid with HMA, and then transparent curing compound will be used. Either type of curing compound will be applied in 2 coats at a rate of not less than 1 gallon per 25 yd² for each coat.

Insulated blankets having a minimum thickness of 2 inches will be placed over the repaired area when the curing compound has been applied and when the air temperature during the curing period falls below 50°F for all concrete repairs. Edges and seams in the blanket will be secured to prevent loss of heat. Test beams, for open to traffic strengths, will be cured the same as the repair. Insulated blankets may be removed when the concrete has attained a flexural strength of 300 psi for P-NC concrete and 550 psi for P1 and P1M concrete.

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[edit] Strength Requirements

The concrete repairs may be opened to traffic when the concrete has attained a flexural strength of 300 psi for repairs constructed with Type P-NC concrete, and 550 psi for repairs constructed with Grade P1 or P1M concrete. Traffic may be allowed over the repair before cleaning and sealing the joints.

Strength test beams, for acceptance and open to traffic, should be made on the job and cured the same as the repairs. This includes being placed under the blankets if blankets are used as an aid to curing. Beams should be cast at the start of the pour and broken at different times to establish the length of curing time necessary to reach the required strength. Increasing or decreasing the time between making and testing the beams will give the inspector a good indication of the time needed to achieve the required strength.

The flexural strength is calculated using the following equation per ASTM C293 – Standard Test Method for Flexural Strength of Concrete (Using Simple Beam With Center Point Loading):


Flexural Strength of Concrete (Using Simple Beam With Center Point Loading):

Where:

R = modulus of rupture or flexural strength in psi
P = maximum applied load in lbs
L = span length in inches
b = average specimen width in inches
d = average specimen depth in inches


Calculate the average specimen width (b) and depth (d) by measuring the width and depth at each end of the beam and taking the average of those measurements.

Beam Measurements

When using a concrete beam tester with center point loading and a 16 inch span length (L), the flexural strength equation above may be simplified using the modulus of rupture factors in table 1. The simplified equation is as follows:


Simplified Center Point Flexural Strength Equation

Where:

F = modulus of rupture factor in in²


Table 1: Modulus of Rupture Factors (F)

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[edit] Sawing and Sealing Joints

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[edit] Sawing Joints

The joint reservoir of the Erg joints will be saw cut 1 inch wide and 1-1/2 inch deep. The joint reservoir for the Crg joints will be saw cut 1/2 inch wide and 3/4 inch deep. Both types of joint reservoirs shall extend the full width of the patch. The Contractor may saw an initial relief cut or saw to the plan dimensions as soon as the concrete has hardened sufficiently so that no excess raveling or spalling occurs. All edging will be done with a 1/8 inch to 1/4 inch radius along the entire perimeter before texturing.

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[edit] Cleaning Joints

All concrete remaining on top of the expansion joint filler will be removed before abrasive blast cleaning. All joints to be sealed will be abrasive blast cleaned and then cleaned with a jet of compressed air, free of oil and water, having a minimum pressure of 90 psi, immediately before sealing.

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[edit] Sealing Joints

All joints and all saw cuts that were made in pavements, shoulders or gutters over cutting will be cleaned and then sealed. Longitudinal bulkhead joints, joints in base course repairs, joints in repairs constructed in preparation for HMA overlays and Trg joints will not be constructed with joint reservoirs and need not be sealed. A backer rod will be placed in the bottom of Cp and Crg joint reservoirs after the final cleaning and before sealing with hot-poured sealant. Seal the joint reservoir to no greater than 1/8 inch (after cooling) below the concrete pavement surface.

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[edit] HMA Shoulder Replacement

Before opening to traffic, HMA shoulders will be restored to the existing line and grade using a plant-mixed HMA mixture, as directed by the Engineer. Cold patch mixtures used for temporary patching will be replaced with plant-mixed HMA mixtures, unless shoulder reconstruction is a part of the project and has not been completed. The HMA mixture will be compacted by mechanical or hand methods suitable for the size hole being filled. HMA plant mixtures will be placed at a temperature suitable for compaction. Concrete shoulders will be constructed as shown on the plans. Materials removed from the shoulder will be disposed of by the Contractor.

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[edit] Diamond Grinding and Longitudinal Grooving

Diamond grinding is used to restore the surface longitudinal profile and improved ride quality of a PCC pavement. And many times is done in conjunction with other PCC pavement restoration treatments. Grinding is performed on the roadbed in the longitudinal direction for the entire lane width as specified on the plans.

Usually 54 to 59 blades per foot are required to produce a level surface with a corduroy-type texture. The peaks and ridges of the corduroy should average 1/8 inch. If the area ground results in a surface with fins more than 1/4 inch high, the spacing of the blades should be adjusted. Grinding equipment that causes ravels, aggregate fractures, spalls or distress of the transverse or longitudinal joint should not be permitted.

The transition between ground and unground pavements should be gradual and result in an acceptable ride quality. Care should be taken to assure that positive drainage is maintained at all times in the transitions between the mainline edge and auxiliary lanes, ramp lanes and shoulders.

Groove pavement 0.12 ± 0.03 inches wide by 0.16 ± 0.03 inches in depth, with a land area between the grooves of 0.75 ± 0.05 inches.

When the Special Provision for Pavement Ride Quality is included in the contract, the Engineer will submit the Ride Quality Plan to the pavement evaluation group at Construction Field Services for concurrent review and to coordinate ride quality acceptance testing.

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[edit] Control and Disposal of Grinding Residue

The requirements for disposing of grinding residue are detailed in the Special Provision for Managing Diamond Grinding Slurry from Ride Quality Concrete. The grinding operation produces slurry of ground concrete and water to cool the blades. Prior to beginning the grinding operation, the Engineer will approve the disposal method. At no time should slurry be discharged within 100 feet of any natural stream or lake or within 5 feet of a water-filled ditch. Nor should it be allowed to enter a closed drain system. Check the project proposal for allowed discharge areas.

Random samples of the slurry should be taken for chemical testing of the grinding residue and cooling water.

The inspector should make the following checks during the diamond grinding operation:

  • Texture
  • Overlap of successive passes of grinding head
  • Blade Spalling
  • Pattern
  • Aggregate hardness
  • Sand Patch test to verify macro texture depth

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[edit] MEASUREMENT AND PAYMENT

-Reserved-

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Division 2 - Earthwork
Division 3 - Base Courses
Division 4 - Drainage Features
Division 5 - HMA Pavements and Surface Treatments
Division 6 - PCC Pavement Mixtures
Division 7 - Structures
Division 8 - Incidental Construction
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