GDOT Section 407: Asphalt-Rubber Joint and Crack Seal

407.1 General Description

This work includes filling (Type M) or sealing (Type S) joints and cracks in existing pavements with rubber asphalt mixtures. A polymer-modified asphalt rubber (PMAR) blend may be used in lieu of both Type M and Type S.

407.1.01 Definitions

Type M: Used to fill joints and cracks in Portland cement concrete or asphaltic concrete pavements when required by the plans before placing an overlay. Type S: Used to seal joints and cracks in Portland cement concrete and asphaltic concrete pavements and shoulders when not placing an overlay.

407.1.02 Related References

A. Standard Specifications Section 820—Asphalt Cement B. Referenced Documents AASHTO T51 ASTM D 4 ASTM D 36 ASTM D 5329 ASTM D 7173 GDT-2 SOP 22 QPL 92

407.1.03 Submittals

Provide a Certificate of Analysis certifying each lot of premixed material meets the requirements of this specification and submit the test results of each lot for each project. Ensure each sealant lot is delivered in containers with the manufacturer’s name or trademark and lot number plainly marked. When instructed by the Engineer, furnish premixed samples and samples of the individual components of premixed material as follows: • At least 20 lbs. (10 kg) of rubber representative of each lot • At least 5 gal (18 L) of asphalt containing additives as proportioned • Proportional quantities of mixing aids or additives not included above • Packaged premixed sealant material weighing no more than 30 lbs. (14 kg)

407.2 Materials

Ensure the sealant material is a premixed, asphalt-rubber sealant mixture evaluated in accordance with SOP 22 and listed on QPLs 92-A, 92-B and/or 92-C. Ensure the mixture is a blend of asphalt cement, aromatic extender oil(s), and recycled or reclaimed tire crumb rubber with rubber contents meeting the requirements specified in Table 2. The blending will be conducted in a closely controlled manufacturing process as detailed in the manufacturer’s submitted Quality Control Plan. Produce a mixture with the following properties: A. Workability The mixture pours readily and penetrates a 1/4 in. (6 mm) pavement joint or crack to a depth of at least 1 in. (25 mm) when the application temperature of the fully reacted mixture is 350 ºF (177 ºC) and the air temperature is 35 ºF (2 ºC) or higher. The mixture, when placed in conventional field installation equipment, readily melts to a pumping consistency after being heated to 400 °F (204 °C) for 2 hours maximum. The mixture remains in a pumping consistency when the temperature of the field installation equipment is reduced to the normal operating temperature range of 300 ºF to 350 ºF (149 ºC to 177 ºC). B. Curing The mixture contains no water or volatile solvents and cures immediately when cooled to a sufficient viscosity to prevent tracking caused by traffic. C. Softening Point, Flexibility and Rubber Content. When a fully reacted mixture sample of asphalt-rubber has been heated at 350 ºF (177 ºC) for one hour, or when a PMAR blend has been heated at 380 ºF (194 ºC) for one hour, ensure it passes the following laboratory tests: 1. Softening Point The minimum softening point by ring and ball described in ASTM D 36 is as follows: TABLE 1 – MINIMUM SOFTENING POINT PMAR 185 ºF (85 ºC) Type S 135 ºF (57 ºC) Type M 150 ºF (65 ºC) 2. Flexibility Bend a 1/8 in. (3 mm) thick x 1 in. (25 mm) wide x 6 in. (150 mm) long mixture specimen after conditioning to 10 ºF (-12 ºC) at a minimum bending rate of 9 degrees per second (10 seconds maximum for a 90º bend) over a 1 in. (25 mm) diameter mandrel without cracking. 3. Rubber Content % Type M and Type S minimum rubber content %. TABLE 2 – TYPE S AND TYPE M MINIMUM RUBBER CONTENT Type S 15% minimum Type M 15% minimum D. Separation Test the PMAR blend for phase separation by pouring two representative samples of the mixture into aluminum tubes measuring 1 in. (25 mm) in diameter and 5-1/2 in. (140 mm) long as described in ASTM D 7173. Cure the samples at 325 ºF (163 ºC) for 48 hours. Take samples from the top and bottom of each tube and determine softening point as described in ASTM D 36. Average the test results from the top and bottom samples. If there is 4 percent or more difference between the average test result and either of the top or bottom test results, reject the mixture due to separation. E. Adhesion When cooled, the mixture bonds strongly to both asphalt and concrete pavement surfaces. The mixture contains no materials chemically reactive with these surfaces to reduce the short-term and long-term adhesion bonds. F. Acceptable Recycled or Reclaimed Tire Crumb Rubber Before the rubber is added, ensure the asphalt cement used in the mixture conforms to the requirements of Section 820.2.01, PG 58-22 or PG 64-22. Ensure the recycled, reclaimed tire crumb rubber used in the mixture meets the following requirements: • Obtained from used pneumatic tires (such as automobile, truck, bus, etc.)—not solid tires and non-tire rubber sources • Produced from an ambient or cryogenic grinding process (crushes, tears, factures or grinds, the used rubber tires and produces rubber particles with a ragged, sponge-like surface). Tire buffings are prohibited. • Contains recycled, vulcanized crumb rubber and/or reclaimed (devulcanized) rubber • Contains at least 25 percent natural rubber by weight of the total rubber portion of the mixture • Contains no more than 0.1 percent fabric • Free of wire and other contaminating materials, except up to four percent calcium carbonate or talc to prevent rubber particles from sticking • Contains no rubber particles greater than 1/4 in. (6 mm) long • Meets the following gradation requirements: TABLE 3 – RECYCLED OR RECLAIMED TIRE CRUMB RUBBER GRADATION Sieve Size Percent Passing No. 10 (2.0 mm) 100% No. 16 (1.18 mm) 95 to 100% No. 30 (600 µm) 40 to 80% No. 80 (180 µm) 0 to 5% G. Polymer-modified Asphalt Rubber If a PMAR blend is used, ensure it meets the following additional requirements: TABLE 4 – POLYMER-MODIFIED ASPHALT RUBBER PROPERTIES (PMAR) PROPERTY SPECIFICATION LIMITS Cone Penetration, 77 ºF (25 ºC) (ASTM D 5329) 30 - 60 dmm Resilience, 77 ºF (25 ºC), % Recovery (ASTM D 5329) 30% minimum Ductility, 77 ºF (25 ºC), 50 mm/minute (ASSHTO T-51) 300 mm minimum Asphalt Compatibility (ASTM D 5329) Pass Bitumen Content (ASTM D 4) 60 – 70 % Tensile Adhesion (ASTM D 5329) 350 % minimum Rotational Viscosity (Brookfield), No. 5 spindle, 20 RPM, 400 ºF (205 ºC) 3,000 – 15,000 cp Rubber Content % (GDT-2) 12% minimum

407.2.01 Delivery, Storage, and Handling

Package the premixed sealant material in units weighing no more than 30 lbs. (14 kg) with a maximum of two 30 lb. (14 kg) units per shipping container. Ensure the plastic film used to package the units melts at normal application temperatures when placed in the installation equipment.