505 ASPHALT PATCHES
From MDOT Policy Manual
- Repair rigid, flexible, or composite pavements by removing part or all of the section of the existing pavement and replace with asphalt paving material. The locations and extent of the repairs will be as specified or as directed.
- Partial Depth Patching (PDP). PDP consists of removing areas of unsound pavement up to 50 percent of the pavement thickness and replacing with an asphalt mix. The pavement thickness is defined as the thickness of all bound materials in the pavement structure including asphalt mix, Portland cement concrete (PCC), and any other asphalt or cement modified material.
- Full Depth Patching (FDP). FDP consists of removing the full thickness of the pavement sections to the top of the aggregate base and replacing with an asphalt mix. Perform FDP whenever more than 50 percent of the pavement thickness requires repair.
Graded Aggregate Base 901.01 Aggregates for Asphalt Mixes 901.01 Performance Graded Asphalt Binders and Asphalt Mixes 904 Crack Filler 911.01 Production Plants 915 Cold Patch Material 924
- Keep disturbance of the base material to a minimum. The faces of the remaining pavement shall be square and vertical without ragged edges. Do not use equipment that could damage the existing pavement.
- 505.03.01 Weather Restrictions. Refer to 504.03.02.
- 505.03.02 Existing Pavement. Complete all repairs on the same day in which excavation is completed. Do not leave open excavated areas at the end of the workday.
- 505.03.03 Removal of Pavement for PDP. Remove existing pavement by milling, grinding, or saw cutting to the specified depth. Maintain square vertical faces after removal.
- (a) If concrete is encountered during removal, limit the depth of the patch to the top elevation of the PCC.
- (b) For PDP of composite pavements, protect the PCC from damage during removal of the asphalt mix.
- (c) When the material at the bottom of the PDP is determined to be unsuitable, remove the unsuitable material until sound material is encountered.
- (d) When any PCC present in a composite pavement is determined to be unsuitable, follow the removal and replacement procedures for a FDP.
- (e) Remove all loose and foreign materials before placing the patch, then treat all spalled cracks and joints by tack coating, filling and tamping with asphalt.
- 505.03.04 Removal of Pavement for FDP. Make a perpendicular saw cut full depth around the perimeter and remove the existing pavement to the top of the aggregate base. Refer to 522.03.03 for the concrete portion of a composite pavement. Maintain square vertical faces after saw cutting.
- 505.03.05 Base and SubgradeThe top surface of a roadbed upon which the pavement structure, shoulders, and curbs are constructed. Preparation. The aggregate base of the FDP area will be evaluated to determine its suitability.
- (a) When the aggregate base is determined to be unstable, compact it as specified in 501.03.10.
- (b) When no aggregate base is present, construct the subgrade foundation per Section 208 or as directed.
- (c) Removal of Unsuitable Material:
- (1) When the aggregate base or subgrade material is unsuitable, remove and dispose of the unsuitable material.
- (2) Replace the unsuitable material with graded aggregate base conforming to Section 501.
- (3) Compact the replacement material in layers no greater than 4 in. depth.
- (4) Protect the aggregate base or subgrade after placement.
- (5) Remove and replace any aggregate base or subgrade damaged due to lack of protection at no additional cost.
- 505.03.06 SubgradeThe top surface of a roadbed upon which the pavement structure, shoulders, and curbs are constructed. Drains. Refer to Section 306. The construction of subgrade drains may be required in areas of wet underlying subgrade or in areas where future drainage problems may be a concern, as determined.
- 505.03.07 Emergency Filler. Have sufficient approved cold patch material readily available to fill the void of the repair area. Place and compact the material as directed. Completely remove the material at the beginning of the next workday.
- 505.03.08 Steel Plates. Ensure that an ample supply of 12 x 14 ft by 1 in. thick steel plates are available on site to cover the emergency filler.
- 505.03.09 Patch Construction. Refer to Section 504. Furnish equipment and perform placement, compaction, and quality control procedures as specified. Manual placement of the asphalt patches is permissible. Thoroughly clean and tack the exposed vertical surface of adjacent pavement prior to placing the asphalt patch per 504.03.04. Patches in excess of 50 ft. in length and 10 ft. or greater in width shall have the final riding surface placed by a paver. Lower lifts may be placed by a paver or other methods as necessary. Do not place asphalt patches on a frozen base.
- 505.03.10 Patch Placement. Maintain lift thickness in conformance with the following:
ASPHALT LIFT THICKNESS MIX DESIGNATION (mm) MINIMUM (in.) MAXIMUM (in.) 9.5 1.0 2.0 12.5 1.5 3.0 19.0 2.0 4.0 25.0 3.0 5.0 37.5 4.0 6.0
- 505.03.11 Patch Surface Checks. Have an approved 10 ft straightedge available as directed. The patch surface, after final compaction, shall be sufficiently smooth and true to the established line and grade. Test the surface with the straightedge in the longitudinal and transverse direction immediately behind the final roller. The tested surface shall not deviate by more than 3/16 in.
- Correct any portions that deviate by more than 3/16 in. by removal and replacement or by diamond grinding at no additional cost.
- Recheck all corrected pavement sections, including any additional transverse paving joints created, to determine if the sections meet specifications.
- 505.03.12 Mix Sampling Requirements. One random sample per mix will be required daily for projects using more than 200 tons per day. Quantities of 200 tons or less of asphalt per day may not require daily field sampling. However, one random sample per mix for every 1000 tons of asphalt or one sample per mix will be required weekly; whichever yields the greater frequency. Random mix samples will be required for patches placed with a paver. Patches not placed with a paver or patches less than 1000 sq ft. (10 ft wide x 100 ft long) will not require a mix sample.
- 505.03.13 Testing and Acceptance. Acceptance of Base and/or Surface of each patch per lift will be determined by using an asphalt density gauge with test data witnessed. Calibrate the density gauge to the mix in order to obtain representative readings.
- 505.03.14 Density Determination Requirements. On the first day of patching, perform density gauge testing and core sampling on three randomly selected test locations. Label the cores with the date sampled. Test the cores then submit the results to OMT. The average pcf of the three cores and the average pcf of two corresponding gauge readings shall be within 3.0 lb/ft3 of each other. If they do not compare, recalibrate the density gauge according to the manufacturer’s recommendation. When the difference between the gauge readings and the core tests are greater than 3.0 lb/ft3, verify the gauge’s accuracy by reading three new random locations. Report the density gauge test data as a percentage of the daily production maximum specific gravity.
- An in-place density of 92.0 to 97.0 percent is required for each randomly selected patch test location per lift. Compliance will be determined for each patch separately by averaging all density tests performed within each specific patch. Submit compaction sheets to OMT daily for all production. Retain the tested cores in the QC LaboratoryThe testing laboratory of the State Highway Administration (or other Administrations) or any other testing laboratory designated by the procurement officer. until OMT verifies the results.
- A patch 2500 linear ft. or greater shall require additional readings.
- Take three cores and corresponding gauge readings per mix weekly to verify the gauge readings. If the average of the density gauge readings and the average of the core densities are within 3.0 lb/ft3, all the daily density gauge readings will be accepted. If they do not compare, recalibrate the density gauge. Incentives are not applicable for patch density.
505.04 MEASUREMENT AND PAYMENT.
- Refer to 504.04 and MSMT 735. Payment will be full compensation for saw cutting, milling, grinding, removal, disposal, trimming of the existing pavement, subgrade preparation, placing all materials including tack coat, steel plates, emergency filler, and for all material, labor, equipment, tools, and incidentals necessary to complete the work. After removal, steel plates and emergency filler will remain the property of the ContractorAny person having a Contract with a procurement agency. Contractor does not include an employee with an employment Contract, or an employee organization with a collective bargaining agreement..
- 505.04.01 Partial Depth Patching and Full Depth Patching. Payment will be measured and paid for at the Contract unit price per square yard or per ton. The payment will be full compensation for furnishing, hauling, placing all material, additional removal of pavement above the aggregate base, and for all material, labor, equipment, tools, and incidentals necessary to complete the work.
- 505.04.02 Removal of Unsuitable Material. Payment will be measured and paid for at the Contract unit price per cubic yard. The payment will also include excavation and disposal of unsuitable material, backfilling with aggregate, and compaction.
- 505.04.03 Price Adjustment for Asphalt Binder. Refer to 504.04.01. An adjustment will be made to the final Contract unit price for asphalt mixture if the price of asphalt binder fluctuates significantly from the prevailing price on the date of placement. This includes asphalt patching material converted to tons.
- 505.04.04 Price Adjustment for Asphalt Mix. Payment reduction or incentive will be made using the Contract items for Asphalt Mixes. Revisions to the established item amounts will not be allowed.