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Full-Depth Repairs

APPENDIX A Generic Guide Specifications

DESCRIPTION: This work shall consist of replacing Portland Cement concrete pavement slabs, full or partial length, removed in accordance with plans or as directed by the Engineer.

MATERIAL: Materials to be used in full-depth repairs shall conform to the following Specifications:

Twenty-Four Hour Accelerated Strength Concrete...........................................Appendix B
Dowel Bars and Bar Coatings................................................................AASHTO M 31M
Epoxy..................................................................................................... ASTM D1763
Deformed Steel Reinforcing Bars ..........................................................AASHTO M 31M
Silicone Sealant ......................................................................................ASTM D 5983

EQUIPMENT: Sufficient equipment, approved by the Engineer prior to starting the Work, shall be used to satisfactorily perform the required work such ad drilling dowel holes, setting dowels, spreading, striking off, consolidating, and screeding concrete, sawing and sealing joints, etc.

CONSTRUCTION:

  1. INSTALL DOWELS: Pneumatic or hydraulic drills and bits that will drill a 35 mm diameter hole in the existing concrete faces for placement of the dowels at location specified on the Plans shall be used.

    If necessary for proper insertion of the dowel bars, the Engineer may allow a 38 mm maximum diameter hole to be drilled.

    The equipment shall be operated so as to prevent damage to the pavement being drilled. The drilling procedure shall be approved by the Engineer. The drilled holes shall be thoroughly cleaned of all contaminants and the dowels of specified type and size shall then be set into the hardened concrete face of the existing pavement with a Type VIII epoxy bounding compound meeting the requirements of ASTM D1763. The specified dowels shall be placed at locations noted on Plan details with one-half of dowel protruding beyond the hardened face of existing pavement and placed at correct horizontal and vertical alignment with misalignment not to exceed 10 mm in the vertical or oblique plane. The epoxy shall be allowed to harden sufficiently prior to placing concrete to prevent any movement of the dowels during the placement of the concrete.

    A sufficient amount of epoxy must be placed in the back of the hole so that the entire cavity around the dowel is completely filled upon insertion of the dowel bars. Any excess epoxy shall be removed. The epoxy adhesive must be packaged in a cartridge with a mixing nozzle that thoroughly mixes the two components as they are dispensed (the mixing nozzle must be a minimum of 200 mm long) or may be placed with a machine which mixes the two components thoroughly and to the proper ratio as the material is being placed.

    Dowels of the type, size, spacing, and at the location specified on the Plans shall be installed in accordance with the Plan details for full-depth repairs.

    The dowel bars which are to be used at the free joints shown on the Plans shall be epoxy coated plain round steel bars meeting the requirement AASHTO M 31M. The protruding portion of the epoxy coated dowels shall be coated with a thin film of grease or other approved material to ensure proper bound-breaking characteristics.

    The dowel bars which are to be used at the "locked" joints shown on the Plans shall be a deformed steel reinforcing bar meeting the requirements of AASHTO M 31M.

    Epoxy coated smooth dowels and the deformed reinforcing bars must have both ends cut clean and smooth with a saw, rather than sheared.

    The deformations on the reinforcing bar must be of such design that the total diameter of the bar, including the deformations, is less than the diameter of the drilled dowel hole.

    At no time shall dowels be driven into a dowel hole with sledge hammers or other devices.

    In all cases, any dowel whether coated or deformed which cannot be freely inserted into a dowel hole will be rejected for use.

    Prior to placing concrete, the vertical exposed faces of the existing slabs shall be thoroughly cleaned of contaminates using wire brushing or other methods approved by the Engineer. Extra care must be taken to remove all existing silicone of other joint sealant form the exposed concrete faces.

  2. SETTING FORMS: Forms will normally not be required for this work as the vertical faces of the existing pavement and shoulder bordering the replace slab/joint area serves as the forms. However, in the event of an irregular or unstable shoulder, a form shall be placed full depth of the replaced slab/joint area so as to maintain a true, straight shoulder joint and to prevent intrusion of the concrete into the shoulder area. The foundation under the form shall be compacted and true to grade so that the form, when set, will be firmly in contact with the base and at the correct grade. Forms shall be cleaned and oiled prior to placing the concrete. Unless otherwise specified, forms shall not be removed form the freshly placed concrete until it has set for at least 4 hours. The forms shall be carefully removed to avoid any damage to the pavement. After removal, the shoulder shall be repaired to the Engineer's satisfaction.

  3. BASE PREPARATION: The base must be cleaned of all debris and any standing water. Loose base material must be thoroughly compacted by hand tampering prior to placing any concrete.

  4. PLACING AND FINISHING CONCRETE: The required concrete for the Work will be twenty-four hour accelerated strength concrete meeting the requirements of Appendix B. The mix design shall be approved by the Laboratory prior to use. The concrete shall be placed only when the ambient temperature is 4C and rising. Concrete shall not be placed when the underlying base material is muddy or frozen. The concrete shall be deposited within the slab replacement area in such manner as to require as little re-handing as possible, to prevent segregation of the mix. Hand spreading shall be minimized as much as possible, but where necessary, shall be done with shovels, not rakes. Workers will not be allowed to walk in the fresh concrete with shoes coated with earth or other foreign substances. The replaced slab area shall be filled with concrete and thoroughly consolidated by rodding, spading, and sufficient vibration to form a dense homogeneous mass throughout the area. The final surface area shall be uniform in appearance and free of irregularities and porous areas.

    The finished surface, including joints, shall meet a surface tolerance of 3 mm to 3 m in any direction. Any necessary corrections shall be done by grinding. Any replaced slab which is low in relation to adjacent slabs may be ordered replaced by the Engineer. The surface tolerance requirement will not be apply when the slab replacements are done in preparation for resurfacing of the pavement.

    Replacement of such a slab would generally be required if, in the opinion of the Engineer, excessive grinding of the adjacent pavement is necessary to match the profile of the full depth slab replacement or if a drainage problem would be created by grinding the adjacent pavement.

    If the Project also involves resurfacing or grinding of the pavement surface, a flat finish will be satisfactory. Otherwise, a broom of hand-tire finish will be required that will produce a surface texture depth of 5 mm or greater. The method of finishing shall be approved by the Engineer.

  5. CURING CONCRETE: All of the applicable portions of Appendix B regarding concrete mix and curing shall also apply to this Work.

  6. SAWING AND SEALING JOINTS: All transverse and longitudinal joints within the slab replacement area shall be established by sawing and sealing with silicone sealant meeting requirement of ASTM D5893. Unless otherwise directed, the width of the sawed joints shall be 10 mm.

    Unless specified otherwise on the plans, the joints shall be sawed and sealed as soon as possible, but not more than 60 days after slab replacement is completed. Sawing and sealing of these re-established joints are to be included in the bid cost for slab replacement.

  7. PROTECTION AGAINST RAIN: The concrete shall be properly protected against the effects of rain before the concrete is hardened. The Contractor shall have available at all times materials for the protection of the surface of the concrete. Such protective materials shall consists of covering materials such as burlap or cotton mats, curing paper, or plastic sheeting material. When rain appears imminent, all paving operations shall stop and all personnel shall begin covering the surface of the unhardened concrete with the protective covering.

  8. NIGHT WORK: If night work is authorized on the Project, adequate lighting shall be provided for all work performed at night, both from a safety and traffic control viewpoint and for satisfactory control and completion of the Work.

  9. OPENING TO TRAFFIC: Unless authorized otherwise on the Project, all slab replacements shall be scheduled so that the concrete will have a minimum curing time of 4 hours and all work completed and all lanes opened to traffic before sunset of the day it is placed. A longer curing period, mix design adjustments, or other corrective action may be required by the Engineer to ensure sufficient strength development of the concrete prior to opening to traffic.

  10. QUALITY OF WORK: The Contractor shall take any control action necessary to ensure the completed work meets or exceeds the requirements specified in the applicable Specifications and Plans. Until final acceptance of this work, the Contractor shall replace any damaged or broken slabs due to improper or unsatisfactory methods, equipment, or materials by the Contractor or due to effects of construction. In additional, the Engineer may require that any replacement slabs have a differential movement at the transverse joints greater than 0.25 mm be removed and replaced.

    This movement will be measured by the Department using an 8,165 kg, single axle load with dual tires with the load centered 300 mm from the edge of the shoulders and as close to the transverse joints as possible. Testing will be done between 3;00 AM and 9:00 AM when maximum slab movement is expected to occur. Measurement will be made with dial gauges capable of detecting movement to the nearest 0.025 mm.

    The Engineer shall determine whether the slab movement test will be required.

MEASUREMENT: Full-depth repairs will be measured for payment by the cubic Meter using the average square dimensions times the average depth.

Dowels and placement of the dowels will not be measured for separate payment but shall be included in the Unit Price bid for full-depth repairs.

PAYMENT: Full-depth repairs will be paid for at the Contract Unit Price per Cubic Meter. Such payment will be full compensation for furnishing all materials and performing the Work, including dowels, epoxy, repair of shoulder if required, removal of unsatisfactory material, 24 hour accelerated strength concrete, sawing and sealing new joints and other work specified.

APPENDIX B
Generic Guide Specifications FULL-DEPTH REPAIRS

TWENTY-FOUR HOUR ACCELERATED STRENGTH CONCRETE

DESCRIPTION: This work shall consist of the manufacture and placement of accelerated strength concrete which has been designed to produce a compressive strength of 20 MPa within 24 hours.

MATERIAL: The materials to be used and their Specifications are listed below:

Portland Cement (Type 1 or Type III)........................................................AASHTO M85
Air-Entraining Admixtures.....................................................................AASHTO M154
Coarse Aggregate, Class A or B, Gravel or Stone.....................................AASHTO M80
Fine Aggregate, Size No. 10 ...................................................................AASHTO M6
Water...................................................................................................AASHTO T-26

A. ACCELERATOR:

The concrete acceleration admixture may be calcium chloride meeting the requirements of AASHTO M 144, Type I or Type II, or the Engineer may authorize the use of a chemical admixture for concrete provided an acceptable concrete design is established in the laboratory with materials representative of those proposed for use. The manufacturer shall submit an affidavit that the chemical admixture for concrete meets the requirements of AASHTO M 194, Type E, Table 1. Accelerators containing chlorides shall not be used in bridges or box culverts when concrete containing the additive will contact reinforcement steel.

ESTABLISHMENT OF CONCRETE MIX PROPORTIONS: The Contractor shall elect one of two procedures for establishing the concrete mix proportions for concrete placed under this provision. The Engineer will be notified which of the following procedures the Contractor elects at least 45 days prior to placement of the concrete.

  1. PROCEDURE FOR CONCRETE MIX PROPORTIONS ESTABLISHED BY THE CONTRACTOR: The Contractor may propose that specific concrete mix design proportions be used for concrete placed under this provision. When the Contractor proposes to use specific proportions, all materials shall be from approved sources or from materials stored or stockpiled at the site and tested prior to use. The laboratory will verify that the proposed proportions will produce concrete that will develop 20 Mpa within 24 hours. Approval may be given to proposed mixes without laboratory design study when commonly used material combinations are used.

  2. PROCEDURE FOR CONCRETE MIX PROPORTIONS ESTABLISHED BY THE ENGINEER: When the Contractor elects, the concrete mix proportions will be established by the Engineer shall be notified of the proposed sources of all materials. Provided all materials conform to their respective Specifications, the job mix proportions will be established from materials representative of materials proposed for use. The Engineer will determine the minimum cement content, the required) water content, quantities of aggregate, and the addition rates of admixtures based upon materials actually intended for use. The proportions will be available as public information within one month after the Contractor proposes the sources of materials. The job mix design proportions will be based upon the following table:

    Minimum Cement
    (Kg/M3)
    Maximum Water Cement
    Ratio (Kg/Kg)
    Minimum Compressive Strength
    At 24 Hours (MPa)
    Air Content
    (%)
    Slump Range
    (mm)
    446 0.45 20 3-6 50-125

The admixture meeting the requirements of materials established will be accepted for initial design. However, no combination of admixture and cement will be approved which produces undesirable characteristics of set time or strength development. No substitution of materials will be allowed after release of an approved design unless such substitution is approved acceptable by the Engineer.

The Engineer's approval of the design mix does not relieve the Contractor of the responsibility for producing specified strength concrete.

BATCHING AND MIXING MATERIALS:

  1. TRANSIT MIXED CONCRETE: When transit mixed concrete is used for concrete containing an acceleration admixture, the concrete ingredients, excluding the acceleration admixtures and 15 liters of withheld water per cubic meter of concrete, shall be mixed at the plant at mixing speed for 35 revolutions of the drum. The concrete shall be mixed en route to the job site at an agitating speed of no more than three revolutions per minute. The acceleration admixture and withheld mixing water shall be added to the concrete at the job site. The method of addition of the acceleration admixture and withheld mixing water shall be approved by the Engineer and the admixture shall be measured into the concrete within an accuracy of plus or minus three percent. The concrete shall be mixed for 40 additional revolutions at mixing speed after the accelerator and withheld mixing water is added to the mixer. An accelerating admixture shall not be added to any concrete which has attained the age of 45 minutes as measured from the beginning of the initial mixing at the plant.

  2. CENTRAL MIXED CONCRETE: When central mixing of concrete is used for concrete containing an acceleration admixture, all concrete ingredients, excluding acceleration admixture and 10 liters of withheld water per cubic meter, shall be shrink-mixed in the central mixer and mixed en route to the job site at agitating speed. All other provisions of Section A above shall apply for the addition of the acceleration admixture and mixing of concrete at the job site.

  3. PORTABLE MIXERS: Portable mixers may be approved by the Engineer when placement quantities at a given location are less than one cubic meter.

PLACEMENT OF CONCRETE: The Contractor shall provide sufficient labor and equipment to place, consolidate, and screed each batch of concrete within one hour after the cement and first mixing water have been introduced into the mix. No concrete shall be placed when the Contractor does not have sufficient facilities to meet this requirement.

CURING: Concrete curing shall be in accordance with States' standard specifications except that concrete curing period may be waived when test results indicate a compressive strength in excess of 20 MPa.

COMPRESSIVE STRENGTH: Four test cylinders shall be cast for each day of placement. The cylinders shall be stored on or adjacent to the pour in a moist condition. Minimum compressive strength shall be in accordance with either of the following:

  • Strength development at 24 hours, 20 MPa. (Average of two specimens)
  • Strength development at 3 days, 25 MPa. (Average of two specimens)
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Updated: 04/07/2011
 

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