255 Full Depth Pavement Removal and Rigid Replacement

General

During the life of concrete pavement, it is sometimes necessary to make repairs to stop progressive deterioration and to maintain serviceability. Timely repairs restore quality and provide the rideability and life expectancy for which the pavement was designed.

Problems may occur at various stages of the pavement life; it is important that these problems are corrected as they arise. Corrections are often necessary during construction, and these repairs must be of the highest standard in order to achieve the anticipated pavement life. This section establishes a standard repair procedure and provides uniform application for repairs. These standards are applicable at any time throughout the pavement life.

Concrete pavement repairs are classified as full-depth pavement replacement and thin-bonded patching. Full-depth replacement applies when the damage is more extensive than surface scaling or spalling and requires removal and replacement for the full depth of the slab. Thin-bonded patching applies to surface scaling and spalling, spalling at edges and joints, and other surface deterioration that does not extend below the pavement mesh. Compliance with all the provisions of the following standards is necessary to assure durable repairs and to permanently restore the quality of the pavement.

Description (255.01)

When Standard Construction Drawing BP-2.5 is called for, rigid replacement applies to the work. The basic process of full-depth repairs includes the following:

1. Full-depth diamond blade sawing.

2. Removing the existing pavement full-depth.

3. Removing base material, if specified.

4. Compaction of base material.

5. Drilling dowel bar or tie bar holes.

6. Furnishing and grouting dowel bars and tiebars.

7. Installing mesh when required.

8. Placing, consolidating, finishing, and curing concrete.

9. Sealing of repaired surface perimeter.

10. Restoring affected shoulders.

Materials (255.02)

Concrete

The concrete to be used must be 499 Class QC 1, QC FS, or QC MS and will be called out in the pay item description. Additionally, Rapid Repair Concrete Mix (RRCM) may be called out in the pay item description. The RRCM mix will require the Contractor to develop and submit a mix design to the Engineer. The RRCM mix design must develop 400 psi flexural strength in no less than 4 hours and no more than 6 hours using a 6-inch x 6-inch (150 mm x 150 mm) beam sample conforming to ASTM C293. The Engineer has 10 days to review and accept or reject the RRCM design.

Curing Materials

The curing material to be furnished and used must be white-pigmented, liquid membrane forming compounds meeting 705.07. The shipping containers must be equipped with mechanical agitators to agitate the material prior to use.

Non-shrink, Non-metallic Grout

The dowels and tiebars must be anchored with non-shrink, non-metallic grout material and must set within 30 minutes. Item 705.20 provides the requirements for grout. The Inspector should check to ensure the proposed grout is on ODOT’s Qualified Products List.

Reinforcing Steel 709.00

Reinforcing steel for dowel bars, basket assemblies, deformed bars, tiebars, hook bolts, wiggle bolts, and couplings must be epoxy coated steel.

Welded Steel Wire Fabric

Welded steel wire fabric, also called steel mesh, must comply with Item 709.00.

Dowel Bars and Basket Assemblies

Dowel bars may be epoxy coated steel 709.13 or Fiber Reinforced Polymer (FRP) bars 705.01. Basket assemblies must be epoxy coated steel.

Removal of Existing Pavement (255.03)

The Engineer must mark the limits of the areas to be repaired. The minimum longitudinal length of a repair is 6 feet (1.8 meters). All pavement repairs must be the full lane width, unless otherwise detailed by the plans.

The existing pavement is sawed full-depth at the limits established by the Engineer with a diamond saw blade. Normally, the existing concrete pavement thickness is given in the plans; however, there may be projects where the existing pavement was built thicker than shown in the repair plan.

Figure 255.A – Full-Depth Diamond Blade Saws

Concrete sawing and removal depths may be as much as 1 inch (25 mm) greater than indicated on the repair plan without additional compensation to the Contractor.

If there is an existing asphalt overlay on the concrete pavement, the Contractor may elect to saw full-depth through the asphalt concrete and the Portland cement concrete. Depending on the thickness of each material, the Contractor may not be capable of sawing through both courses and may make an offset saw cut through the asphalt course, remove enough asphalt to allow room for a diamond saw, then make a full-depth saw cut through the concrete pavement. If the Contractor elects to make offset cuts to facilitate removal, the offset cut will not be measured for payment. Only full-depth saw cuts that are made at the limits of the removal are measured for payment. Any intermediate saw cuts made by the Contractor to facilitate removal by the lift out method are not measured for payment.

During hot weather, it may be necessary for the Contractor to saw only at night or in the morning when cooler temperatures prevail. Concrete pavement heats up and expands as temperatures rise during hot summer days. Diamond saw blades could be pinched and lock up when sawing due to slab expansion. Some contractors use a carbide-tipped saw to cut through the pavement within the repair area. This is permitted provided that the Contractor does not damage the base under the pavement to be removed. All perimeter saw cuts must be made with diamond saws.

Figure 255.B – Pavement Removal by the Lift-out Method

Removal of the concrete follows the full-depth sawing operation. The lift-out method is required in order to not disturb the base material under the pavement and to minimize damage to the adjacent pavement that is to remain. Holes are drilled within the removal area and lift pins are inserted. The slab, or portion of the slab, is then removed by lifting the slab vertically with a crane or large backhoe. After lifting, loose debris left behind is removed by hand. The removed pavement is disposed of in accordance with Item 202.02.

The use of a pavement breaker and backhoe for removal is not permitted unless the Engineer determines that the lift-out method is not practical due to extensively deteriorated pavement, the existence of asphalt concrete full-depth repairs, or old concrete pavement repairs, which are extensively cracked and deteriorated. There will be no additional compensation for removal of the existing pavement with a pavement breaker and backhoe.

Regardless of the method used to remove the pavement, if the face of the pavement to remain is damaged by sawing or removal operations, an additional full-depth saw cut is required for the full width of the lane or lanes at a distance from the first cut, which includes the damaged pavement. The additional pavement repair area and the additional saw cut is not measured for payment.

After pavement is removed from the area to be repaired, an additional saw cut must be made if the face of the remaining pavement or shoulder is deteriorated on the bottom to a height greater than 1/4 of the pavement thickness. The additional saw cut should encompass the deteriorated areas. The additional saw cut and repair area is measured for payment.

Removed pavement shall be disposed of in accordance with 202.02. The Inspector shall determine and document where and how pavement is being disposed by the Contractor.

Correction of Subgrade (255.04)

Prior to placing the concrete in the removal area, and before installing dowels or tiebars, shape and compact the base or subgrade material. Any area that has been over-excavated must be filled with concrete.

Figure 255.C – Debris Remaining after Removal by the Lift-Out Method is Removed by Hand Methods

Figure 255.D – Compaction of Base

If undercut joints at the limits of the repair areas are specified, the Contractor must be careful when removing the base material to create the undercut section. The undercut section is the void created by removing the base material from underneath the existing, remaining pavement. This undercut will be filled with concrete when placing the new pavement repair. Refer to Standard Construction Drawing BP-2.5 for undercut joint details. Damage to the bottom of the slab that is to remain cannot be tolerated. Any damage caused by the Contractor’s operations requires additional removal and replacement at no additional cost. If a backhoe bucket plate is used, exercise care, or use hand methods to excavate under the existing slab. Undercut work is incidental and included in the pay item.

Placing Dowels and Tiebars (255.05)

Dowels could be smooth or deformed steel bars depending on the type of joint (transverse contraction or transverse tied). Smooth dowels are 1-1/2 inch (38 mm) in diameter by 14 inches (355 mm) in length. Fiber-reinforced polymer dowel bars may be used in lieu of smooth steel dowels. Deformed bars are No. 11 (No. 35M) by 14 inches (355 mm) in length. Refer to Standard Construction Drawing BP-2.5 for details on tied and contraction joint requirements.

Holes for dowels and tie bars are drilled in the existing concrete slab by using hydraulic or electric drills. Drilling is to be done in a manner that will not spall or damage the existing concrete. Pneumatic drills are not to be used. Holes must be drilled with a device that allows independent adjustment of all drill shafts in the horizontal and vertical direction. The device must be capable of drilling a minimum of three holes at one time.

Holes for dowel and tie bars are to be centered at mid-slab within a tolerance of ±1/2 inch (13 mm). Dowels are spaced starting 12 inches (300 mm) from the outside edge of pavement, are spaced at 12 inches (305 mm), and stop 24 inches (600 mm) from the adjacent lane to avoid hitting existing tiebars at the longitudinal joint. This will result in 10 bars in each 12 foot lane. The Contractor must drill dowel holes parallel to the pavement surface and the centerline, otherwise the smooth dowels will not perform properly when the pavement expands and contracts.

Figure 255.E – Hole Drilling Equipment

Holes for dowels or tiebars must be 1-5/8 inches (41 mm) in diameter and a minimum of 7 inches (178 mm) deep into the concrete.

Longitudinal Joints

Full-depth repairs that are greater than 10 feet (3.0 meters) in length will require a tied longitudinal joint using No. 5 x 24-inch (No. 16M x 600) tiebars or hook bolts spaced at no more than 30 inches (760 mm) and not less than 24 inches (610 mm). Refer to Standard Construction Drawings BP-2.1 and BP-2.5 for more details. Holes for longitudinal tiebars must be 3/4 inches (19 mm) in diameter and a minimum of 12 inches (300 mm) deep into the concrete.

Grouting Dowels or Tiebars

This section details the requirements for transverse dowels and tiebars. The requirements for tied longitudinal joints are the same; however, the bar dimensions differ. All dowels and tiebars must be grouted into place with a non-shrink, non-metallic grout material. Prior to injecting grout, the holes must be blown clean with oil-free compressed air. The hole must be dry and frost free before grouting dowels or tiebars.

The grout must be injected pneumatically into the back of the hole and the dowel or tiebar inserted 7 inches (178 mm) into the hole. A nylon or plastic washer (called a grout retention disc) is then pushed flush against the saw cut after the bar is installed to keep the grout in the hole. Grout retention discs must be clear or opaque white in color. Sufficient grout must be used to completely fill all voids around the bar, including any spalling at the face of the saw cut. Grout should extrude through the slot in the grout retention disc after filling and inserting the dowel or tiebar. Other methods of installing dowels or tiebars are not permitted.

Figure 255.F – Typical Grout Injection Equipment

Figure 255.G – Pneumatic Injection of Grout into Hole Prior to Installing Dowel Bar with Grout Retention Disc

Most contractors pump the resin and hardener from separate pressure pots. The two materials are mixed immediately before being injected into the hole through a baffled mixing tube. In cooler temperatures, it may be necessary to heat the grout materials to promote flow and to allow set up in the required 30 minute time period. Dowels or tiebars must be held in proper alignment until the grout has hardened.

Figure 255.H – Insert Steel Rods with Grout Discs in Place

Figure 255.I – Using a Spud Bar to Push Steel Rod into Place

Placement of Portland Cement Concrete (255.06)

Placement of the concrete can begin when the grout around dowels or tiebars has hardened. Smooth dowels must be coated with new, light form oil before concrete is placed. Rigid forms are required at the outside edge of the full-depth repair. The concrete must be placed in a continuous operation and consolidated with internal vibration.

Figure 255.J – Rigid Forms Installed at Shoulders

Full-depth repairs that are greater than 10 feet (3.0 meters) in length, or will be opened to traffic within 24 hours of placement, require W8.5 or D8.5 wire fabric reinforcement. The clearance from the end of the wire fabric to the edge of the pavement or new transverse joint is 4 ± 2 inches (100 mm ± 50 mm). Refer to Standard Construction Drawing BP-2.5 for details.

When using RRCM concrete the Contractor is required to install maturity sensors to measure the maturity of each day’s placement. At least two sensors should be installed for each work day. Install the first sensor where maturity gain is expected to be the slowest. Maturity gain is typically slowest in the thinnest section of pavement or volumetrically smallest patch or repair. If all sections, patches, or repairs have the same dimensions and no concrete is expected to gain maturity slower than another, install the first sensor randomly in concrete from any load, except the last load. Install the other sensor in concrete from the last load mixed and placed that day. See Supplement 1098 for additional details on maturity curve development and use during construction.

Figure 255.K – Screeding of Repair Area

Figure 255.L – Bull Floating the Repair Area

Specifications require that repairs less than 12 feet (3.7 meters) in length be screeded parallel with the centerline. If the repair is 12 feet (3.7 meters) or longer in length, the screed must be perpendicular to the centerline. After screeding and floating is complete, the surface must be tested with a 10 foot (3.0 meter) straightedge before the concrete hardens to ensure that the transition on and off the repair meets a tolerance of 1/8 inch in 10 feet (3 mm in 3.0 m). Any high or low areas must be corrected and the surface rechecked to assure compliance.

The surface finish of the concrete repair must match the adjacent concrete. If the adjacent pavement is smoothed with a burlap drag, the patch should have the same finish. If the patch texture is different, it may be very noticeable when traveling over the patch at normal traffic speed.

After finishing and straightedge checking is complete, the concrete must be cured with white pigmented curing membrane as per 705.07, Type 2. A uniform coverage of membrane is required at an application rate of 150 square feet per gallon (1 liter per 3.7 square meters).

Wearing Course Replacement (255.07)

If asphalt was removed from the top of the existing pavement, it must be replaced with either 301 or 448 Type II material as shown in the plans. Compact these mixtures as approved by the Engineer using any of the roller types specified in 401.13. Prior to placing the hot mix asphalt concrete, apply a tack coat on the repaired surface per 407.

Vertically trim all transverse joints to a 1-1/2 inch (38 mm) minimum before placing the final asphalt concrete layer adjacent to the existing pavement.

Seal the perimeter surface of repaired areas 4 inches (100 mm) wide by applying approved 702.04 asphalt material, RS-1, RS-2, CRS-1, CRS-2, or 702.01 approved PG binder.

Shoulders must be restored to the original line and grade with aggregate or asphalt concrete as directed by the Engineer or as shown in the plans. Fill low areas and compact them flush with the surrounding shoulder.

Opening to Traffic (255.08)

Full-depth repairs can be opened to traffic when the concrete attains a modulus of rupture of 400 psi (2.8 Mpa). For RCCM mixes, do not open the rigid replacement to traffic until the RCCM attains a modulus of rupture of 400 pounds per square inch (2.8 MPa) based on maturity testing. The time to obtain this strength will vary depending on the class of concrete used and the atmospheric conditions.

When traffic is maintained adjacent to the lane being repaired, the Contractor must schedule his work so that slab replacements are completed within 48 hours after removing the existing pavement. At the end of a daily work shift, unfilled repairs, 10 feet (3.0 meters) and less in length must be covered with steel plates.

The Contractor must plan work so that no repairs are left unfilled when work is suspended for holidays or weekends. If the Contractor has removed pavement and is unable to complete the repairs in the above time, he must fill the areas with a suitable, temporary patch material to the satisfaction of the Engineer. These areas must be maintained by the Contractor.

Method of Measurement (255.09)

The Department will measure the quantity of full-depth pavement removal and rigid replacement by the number of square yards (square meters) repaired in the completed and accepted work.

Full-depth pavement sawing is measured by the number of feet (meters) of perimeter full-depth saw cuts made in the completed and accepted work. The Department will not measure any offset cuts, pressure relief cuts, or other saw cuts made to facilitate pavement removal.

Basis of Payment (255.10)

Payment is full compensation for all work specified in this item. Payment for accepted quantities of the full-depth pavement removal and rigid replacement item is at the contract price per square yard (square meter).

Payment for the full-depth pavement sawing item is at the Contract price per linear foot (meter). The Department will not pay for additional concrete sawing and removal depths within 1 inch (25 mm) greater than those shown on the plans.

The Department will not pay for additional work to repair damage caused by pavement sawing or pavement removal.

The Department will include tack coat in the cost of the asphalt concrete. The Department will pay for asphalt concrete according to Item 301 or Item 448.

Documentation Requirements - 255 Full Depth Pavement Removal and Rigid Replacement

1. Locate, mark, and record areas to be replaced.

2. Document removal of existing pavement and note if damage occurred due to removal operation.

3. Document the disposal of waste material.

4. Measure and record saw cuts. Full-depth saw cuts are an additional pay item paid by the linear foot.

5. Document any damage to existing base material or subgrade during pavement removal operation.

6. Document preparation and compaction of base material or subgrade.

7. Document type of equipment used for drilling holes for dowel bars; depth of holes; holes blown clean before dowel bars placed.

8. Document dowel and tiebar sizes, spacing, and alignment; approved grout, method of grout placement, and use of grout retention discs.

9. Document placement of concrete in accordance with 451.06 and direction of screeding.

10. Document surface tolerance checks with straightedge and any corrections made.

11. Calculate and document curing compound used and required.

12. Document times and results of beam breaks or maturity readings.

13. Measure and pay as per 255.10.

14. Show documentation on CA-D-6 or other approved form.