MATERIALS. Pavement Overlay Fabric shall be constructed of long chain synthetic polymers composed of at least 85 percent of polyolephines, polyesters, and polyamides by weight, shall be resistant to chemical attack, mildew, and rot, and shall meet the following physical requirements:
| Property | Specification | Test Method |
|---|---|---|
| Grab tensile strength, lbs. * | 100 Min. | ASTM D 4632 |
| Grab elongation, percent ** | 50 Min. | ASTM D 4632 |
| Asphalt retention gal./sy. | 0.25 Min. | AASHTO M-288 | Melting Point (degrees F) | 300 or Greater | ASTM D 276 |
The fabric shall not be exposed to ultraviolet radiation for more than 7 days. The fabric shall be at least 75 inches but no more than 150 inches in width and furnished in rolls of approximately 100 yards in length.
The asphalt sealant shall be PG64-22 meeting the requirements of 702.01. Certification shall be furnished in accordance with 101.061 before the fabric is placed. The engineer may require sampling for testing purposes as directed by the Laboratory.
EQUIPMENT. The Contractor shall provide equipment for heating and applying bituminous material. Heating equipment and distributors shall meet the requirements of 407.
The mechanical laydown equipment shall be mounted on a four-wheeled vehicle that is capable of driving over the fabric while it is being installed to control the tension on the material. The vehicle shall have a minimum wheelbase of 130". The laydown machine shall be equipped with clutches to adjust the roll tension and brooms to smooth out wrinkles during installation. Manual laydown may only be used in areas inaccessible to the laydown machine.
A. Surface Preparation. The cracks and entire road surface to be treated, and at least one addition foot on each side, shall be cleaned by sweeping, blowing, or other methods until all dust, mud, clay lumps, vegetation, and foreign material are removed entirely from the pavement before the bituminous material is applied. Care shall be exercised to prevent material so removed from becoming mixed with the new surface.
B. Application of Asphalt Sealant. The application of the asphalt sealant shall conform to the applicable portions of 407. The asphalt sealant shall be uniformly sprayed over the area to be covered by fabric at a rate of 0.25 to 0.30 gallon per square yard.
The quantity applied will vary with the surface condition of the existing pavement (degree of porosity, for example). The fabric alone, under heat of the overlay, will absorb at least 0.20 gallon per square yard. Within intersections or other zones where vehicle breaking is common place, the application shall be reduced 20 percent. The sealant shall be applied to an area two to six inches wider than the widths of the fabric being placed, but restricted to the area of immediate fabric laydown. Application shall be by distributor with hand spraying allowed only where the distributor cannot be used. Asphalt spills shall be cleaned from the road surface to avoid flushing and possible movement at these asphalt rich areas.
The asphalt cement used as a sealant shall have distributor tank temperature between 300 degrees and 350 degrees F. Application temperature is not critical after the asphalt is sprayed on the pavement. If the fabric is to be over-sprayed, distributor tank temperatures should not exceed 350 degrees F to avoid damage to the fabric.
C. Fabric Placement. The fabric shall be placed on the asphalt sealant as soon as possible and before the tackiness of the sealant is lost. The fabric shall be placed as smoothly as possible to avoid wrinkles. It shall be unrolled so that the soft side is unwound into the sealant, thus providing optimum bond between fabric and pavement during the construction process. Wrinkles severe enough to cause "folds" shall be slit and laid flat. Small wrinkles which flatten under compaction are not detrimental to performance. The fabric shall be broomed or squeegeed to remove air bubbles and make complete contact with the road surface as recommended by the fabric manufacturer. The fabric shall be laid straight, within the sealant area. Moderate curves can be negotiated by stretching the fabric on the outside of the curve by adjusting the drag on the brakes of the laydown equipment.
Longitudinal joints shall be made by overlapping the fabric one to three inches. Transverse joints shall be made by overlapping the fabric four to six inches. Additional sealant shall be added to the joints as required. The additional sealant for transverse joints may be applied by hand spraying or with mop and bucket and care should be taken to avoid excess asphalt cement.
To enhance the bond of the fabric with the existing pavement and to smooth out any wrinkles or folds in the fabric, the Contractor may be required to pneumatically roll the fabric after it is placed.
D. Treatment of the Applied Fabric Prior to the Asphalt Concrete. It is unnecessary to tack coat the fabric prior to placement of the overlay unless there are circumstances such as delay of overlay, dust accumulation or under application of sealant which would make tack coating desirable. If a tack coat is required, emulsified asphalt shall be applied at a rate of 0.02 to 0.05 gallon per square yard residual asphalt. Placement of the asphalt concrete overlay shall closely follow fabric laydown. In the event that the sealant bleeds through the fabric before the asphalt concrete is placed, it may be necessary to blot the sealant by spreading sand or asphalt concrete over the affected areas. This will prevent any tendency for construction equipment to pick up the fabric when driving over it.
Turning of the paver and other vehicles shall be gradual to avoid movement or damage to the membrane. If it is necessary to open the road to traffic after fabric placement, but prior to paving, it is advisable to spread a small amount of sand over the membrane to prevent tires from sticking to the sealant or pulling up the fabric. This practice is to be avoided if possible to prevent damage to the membrane.
If rain prior to the overlay should cause a blistered appearance and some bond loss throughout the membrane, it should be corrected by pneumatic rolling until adhesion is restored.
E. Asphalt Concrete. The asphalt concrete overlay shall conform to 401 except that the mixture shall be delivered to the paver at a temperature of 275 degrees to 300 degrees F. Temperature of the mix shall in no case exceed 325 degrees F.
METHOD OF MEASUREMENT. The accepted fabric placed in accordance with these specifications and as directed will be measured by the square yard of roadway, ramps, and turnouts covered by the fabric. Laps in fabric will not be measured.
Blotting the sealant, spreading sand or asphalt concrete over the membrane to prevent tires from sticking to the sealant or pulling up the fabric, rolling to restore bond, or application of a tack coat will not be measured for direct payment but shall be considered a necessary part of the construction involved and the cost therefore shall be included in other appropriate contract unit prices.
BASIS OF PAYMENT. The accepted quantities of pavement overlay fabric will be paid for at the contract unit price per square yard, which price and payment shall be full compensation for furnishing all labor, materials (including asphalt sealant), tools, equipment and incidentals for doing all the work involved in furnishing and placing the fabric complete is place as shown on the plans or as directed.
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