21-02545 Superpave Base Course.pdf

Job No. WCON 1509

02545-1

SECTION 02545

SUPERPAVE ASPHALT MIXTURE DESIGN,

HMA BASE COURSE

PART 1 GENERAL

1.1 DESCRIPTION

A. This work shall consist of installing a certified plant-mixed HMA base course on a prepared surface within reasonably close conformity to the lines, grades and limits shown on the construction documents. The base course shall be constructed to the minimum compacted depth and density and to the distances below the finished grade, as indicated in the construction documents.

1.2 DESIGN STANDARDS

B. Unless otherwise indicated, the following design standards shall be used:

1. Mix Design – 25mm.

2. Equivalent Single Axle Load – 3.0 to 10.0 million.

3. Performance Grade – PG 64-22.

4. Mat Thickness – 150mm (6-inches) State Highways

200 mm (8-inches) Borough Roads.

B. All standards shall be in accordance with PennDOT Publication 408, latest edition, Sections 309 and 409.

1.3 MIXTURE ACCEPTANCE

A. For Borough Roads, Certification Acceptance level will be used. Criteria for acceptance shall be as specified in PennDOT Publication 408, Section 409.2(f).

B. Provide PennDOT Form CS-4171 from a plant approved in Bulletin 15. Attach all QC test results to the form. Certify mixture as specified in Section 106.03 and the requirements of Section 409.

C. Provide all forms and supporting certifications to the Engineer a minimum of

10-days prior to the commencement of work.

02545-2

D. For State Highways, mixture acceptance may be by other methods, as specified in

PennDOT Publication 408, Section 409. It is incumbent upon the contractor to contact the PennDOT representative to determine which criteria for acceptance will be used for the specific project.

1.4 MATERIAL

C. All material shall be in accordance with Section 409.2 of PennDOT Publication

408, latest edition.

1.5 EQUIPMENT

A. Hauling Equipment.

1. Haul the mixtures in tightly sealed vehicles that do not contain petroleum oils, solvents, or other materials that adversely affect the mix.

2. Provide covers of sufficient size and quality to protect the entire load under all conditions.

3. Maintain the proper and uniform temperature specified in Section

409.3(h)1 of PennDOT Publication 408, latest edition.

4. Provide insulation on all sides of the truck body, a double-walled body, or a heated body when the air temperature is below 50°F.

B. Bituminous Pavers

1. Use self-contained, power-propelled units with activated screeds or activated strike-off assemblies and with automatic screed controls capable of producing a finished surface of the specified evenness and texture.

2. Provide heated units capable of spreading and finishing the mixture to the widths and depths indicated.

3. Provide units capable of being operated at forward speeds consistent with the satisfactory laying of the mixture and equipped with receiving hoppers having sufficient capacity for uniform spreading and equipped with distribution systems that place the mixture uniformly in front of the screeds.

4. Do not use any equipment that tears, shoves, or gouges the mixture or that causes tracks, indented areas, flushing segregation or other permanent blemishes. Do not use blade graders or other earthmoving equipment.

02545-3

C. Rollers

1. Use steel-wheel, pneumatic-tire or vibratory rollers as specified in Section

108.05(c)3 of PennDOT Publication 408, latest edition. Operate rollers according to manufacturer’s recommendations.

1.6 CONSTRUCTION METHODS

A. Time Restrictions

1. Do not place paving mixtures from November 1 to March 31 unless written permission is obtained from Borough or State Officials.

B. Weather Limitations

1. Do not place base course when the air or prepared surface temperature is

35°F or lower.

2. If work is halted because of weather conditions, the Contractor may be permitted to place limited quantities of the base course that is en route to the project provided the placement is approved by the Project

Representative on site.

3. Should the conditions not permit the material to be placed, the Contractor shall have no recourse for payment of any unused material.

C. Preparation of Existing Surface.

1. Thoroughly roll all subgrade with a minimum 10-ton vibratory roller such that the finished product is properly compacted, stable at a uniform elevation and all aggregate is firmly embedded. For areas inaccessible to a roller, use a vibratory plate tamper or jumping jack to achieve the same criteria.

2. Compact subgrade to a minimum percentage specified of the materials maximum dry density as determined by ASTM D-698-70.

For State Highways: minimum 100%

For Borough Roads: minimum 95%

3. If soft areas are encountered, the Engineer may direct the Contractor to allow sufficient time for the subgrade to dry out. If the area cannot be suitably compacted, the Engineer can order it removed and backfilled with

02545-4 suitable material. If soft areas are caused by the Contractor, those areas will be removed and backfilled at the Contractor’s expense.

4. Do not allow equipment on the prepared subbase after final rolling and conditioning.

5. Paint all vertical surfaces of curbs, structures, gutter and pavements that will be in contact with bituminous mixtures with a uniform coating of bituminous material, Class E6 or E8.

D. Spreading and Finishing.

1. Unless otherwise directed, deliver, place and compact pawns, mixtures during daylight hours.

2. Ensure that mixtures are delivered and placed at the following laying temperatures. Ensure mixture does not contain lumps of cold material

TEMPERATURE OF MIXTURE

CLASS OF MATERIAL MIN (°F) MAX (°F)

PG 64-22 265 320

For other classes of material, refer to PennDOT Publication 408, Section

409.2 for temperature ranges.

3. Spread and strike off the mixture for the entire lane width or as much lane width as practical. Adjust screed assemblies to provide the required cross section and depth. After spreading, do not add any mixture to the mat that is segregated, below the minimum temperature, contains either a deficiency or excess of asphalt, or is otherwise unsuitable.

4. In areas where mechanical spreaders cannot be used, place and screed the mixture with suitable hand tools. Do not use rakes.

5. If the base course is more than 150 mm (6-inches), place the course in two or more layers of approximately equal depth, with no layer less than

80 mm (3-inches) or more than 150 mm (6-inches). If the compacted depth of the base course is more than 200 mm (8-inches), please the course in two or more layers of approximately equal depth with no layer less than 100 mm (4-inches) or more than 200 mm (8-inches).

6. Install the base course to within 6 mm (1/4-inch) of final elevations.

Remove and replace any irregularities more than 6 mm (1/4-inch).

02545-5

E. Joints

1. Longitudinal.

a. Plan joint locations to ensure that the joint in the top layer is at the approximate pavement centerline for two-lane roadways and within 300 mm (12-inches) of the lane lines for roadways with more than two lanes. Offset joints in a layer from the joint in the layer immediately below by approximately 150 mm (6-inches).

b. If traffic or other causes distort the lane edge, restore it to its original shape using either a vertical or notched wedged joint per

Section 409.3 of PennDOT Publication 408, latest edition.

2. Transverse.

a. Construct joints perpendicular to the pavement centerline.

b. Provide a true vertical surface and cross section throughout the entire joint.

c. Paint the joint face with a thin coating of bituminous material before placing fresh mixture against the joint face.

F. Compaction.

1. Compact the mixture to achieve the density acceptance requirements and to eliminate all roller marks.

2. Compact the mixture while it is in the proper condition. Adjust roller speed, amplitude, frequency pattern and roller size to eliminate displacement, shoving, cracking and aggregate breakage. Satisfactorily correct all displacement.

3. Maintain wheels of the steel-wheel rollers moist and clean to prevent the mixture from adhering to the wheels.

4. For areas inaccessible to rollers, compact with mechanical vibrating hand tampers.

G. Mat Density Acceptance.

1. Density acceptance level will be either by Non-Movement or Optimum –

Rolling Pattern as outlined in PennDOT Publication 408, Section 409.3.

2. Density limits shall comply with Table E of Section 409.3, Publication

408, latest edition.

02545-6

H. Field Technician.

1. Provide a certified HMA field technician in accordance with the qualifications outlined in Publication 351 to control placement of the bituminous mixtures. The certified HMA field technician must be onsite and carry a valid certification card during placement of all HMA mixtures.

I. Protection of Courses.

1. Do not allow vehicular traffic or loading on newly compacted courses until adequate stability and adhesion is obtained and the material has cooled to 140°F or less.

J. Defective Work.

1. Remove and replace all work determined to be defective by the Engineer.

Defective work will be as defined in PennDOT Publication 408, latest edition, Sections 105, 309 and 409.

2. Defective work will not be measured for payment until it is satisfactorily corrected.

END OF SECTION