427Emulsified Asphalt Slurry Seal

427.1 General Description

This work includes placing slurry seal. Emulsified asphalt slurry seal is a thin application of a mixture of fine non-plastic aggregate, emulsified asphalt, mineral filler, and water.

427.1.01 Definitions

General Provisions 101 through 150.

427.1.02 Related References

A. Standard Specifications Section 413—Bituminous Tack Coat Section 802—Aggregates for Asphaltic Concrete Section 822—Emulsified Asphalt Section 824—Cationic Asphalt Emulsion Section 830—Portland Cement Section 882—Lime Section 883—Mineral Filler B. Referenced Documents GDT 91 GDT 43

427.1.03 Submittals

A. Slurry Seal Design At least two weeks before beginning the work, submit to the Office of Materials and Research (OMR) design s amples of each ingredient to be used in the slurry seal mix. Include in the samples information concerning sources, type of materials, and project number. Do not begin slurry seal work until the OMR has approved the sl urry mix design. Submit the slurry seal mix design that will be used on the Project to the Engineer. B. Equipment Calibration Before placing slurry seal, furnish the Engineer with a calibration of the slurry mixing equipment.

427.2 Materials

Ensure that the materials to be used meet the following specifications: A. Aggregate Ensure that the aggregate used in emulsified asphalt slurry seal meets the requirements of Subsection 802.2.01. Except, use aggregate manufactured from Group II, Class A or B crushed stone or slag with a sand equivalent v alue of at least 50. Ensure that the aggregates shipped to the project are uniform and do not require blending or premixing at the s torage area before use. B. Mineral Filler Material Section Portland Cement 830 and 883 Hydrated Lime 882 and 883 C. Emulsified Asphalt Material Section Emulsified Asphalt: SS-1h 822 Cationic Asphalt Emulsion: CSS-1h 824 D. Water Ensure that water for slurry seal mixtures is clear and free of oil, salt, acid, alkali, organic, and other harmful substances. The Engineer may require a water sample be sent to the OMR for evaluation before work begins on the project. E. Mixture Composition Use an emulsified asphalt slurry seal that is a uniform mixture of aggregate, emulsified asphalt, mineral filler, and water. The Engineer may require any element to be adjusted or replaced to produce an acceptable slurry seal. Proportion the elements to produce a uniform mixture that meets the requirements of the Table below: Emulsified Asphalt Slurry Seal Mixture Mixture Control Tolerances, % Sieve Size % Passing ±0 3/8 in. (9.5 mm) 100 ±6 No. 4 (4.75 mm) 90 to 100 ±5 No. 8 (2.36 mm) 65 to 90 ±4 No. 50 (300 µm) 20 to 45 ±3 No. 200 (75µm) 8 to 16 Design Requirements ±0.75 Range for percent residual asphalt *7.5 to13.5 ±0.2 (5) Flow inch (mm), GDT 91 1 (25) n/a Wear lb./ft.² (g/m²)GDT 43 maximum 0.220 (1075) *Percent residual asphalt is based on weight of the dry aggregate. Emulsified asphalt slurry seal is used to seal small cracks and correct moderate surface condition. Apply this type at a rate of 10 to 20 lbs./yd² (5.5 to 11 kg/m²) based on dry aggregate weight. If more than 20 lbs./yd² (11 kg/m²) of emulsified asphalt slurry seal is required, apply additional lifts of the same mixture. Maintain the gradation and percent residual asphalt as shown on the slurry seal design or as established by the Engineer within the mixture control tolerances listed.

427.2.01 Delivery, Storage, and Handling

A. Transporting and Storing Asphalt Emulsions Transport asphalt emulsions using containers free of foreign material. Asphalt emulsion will not be accepted if a tr ansporting vehicle has leaked or spilled during transit. Store the asphalt emulsion in stationary rail or truck tanks that can be used to fill the slurry seal truck tanks. Equip the storage and truck tanks to prevent water from entering the emulsion. Provide heat if necessary to prevent freezing. B. Stockpiling Aggregates Stockpile the aggregate in an area that drains readily. Take precautions to prevent stockpile contaminations such as soil, vegetation, or oversize rock. Load the aggregate on to the slurry seal trucks without segregating it.

427.3 Construction Requirements

427.3.01 Personnel

General Provisions 101 through 150.

427.3.02 Equipment

Equipment, tools, and machines used to perform this work are subject to the Engineer’s approval. The Engineer may discontinue the work if more equipment and tools are needed to place the materials. Do not use malfunctioning equipment to perform the work. A. Slurry Mixing Equipment Before slurry seal placement begins, furnish the Engineer with a calibration of the slurry mixing equipment. Ensure that the mixing machine is equipped with the following: • Revolution counter to count the feeder belt revolutions continuously or intermittently as desired by the Engineer • Water pressure system and a fog-type spray bar to fog the surface prior to spreading the slurry mix • Continuous flow mixing unit that can deliver a predetermined proportion of aggregate, water, mineral filler, and asphalt emulsion to the mixing chamber and discharge the thoroughly mixed product continuously Pre-wet the aggregate and mineral filler in the machine immediately before mixing it with the emulsion. NOTE: Use caution when mixing to ensure that the emulsion does not set up prematurely. B. Slurry Spreading Equipment Use a mechanical squeegee spreader with a flexible strike-off that contacts the surface (ensure that the spreader is adjustable to spread evenly and to prevent loss of slurry on varying grades and crowns) Use a spreader equipped with augers, a steering device, a flexible strike-off, and a device to adjust the co verage width. Keep the spreader box clean and free of asphalt and aggregate build-up. The type of flexible strike-off and the burlap drags or other drags are subject to the Engineer’s approval. C. Cleaning Equipment Ensure that power brooms, power blowers, air compressors, water flushing equipment, and hand brooms can thoroughly clean cracks and the old surface. D. Auxiliary Equipment Provide hand squeegees, hand brooms, shovels, and other equipment needed to perform the work.

427.3.03 Preparation

Immediately before applying the slurry: 1. Remove loose material, silt spots, vegetation, and other objectionable material from the pavement. If the pavement has considerable cracks, do not flush it with water. 2. Prepare the surface as specified in the Standard Specifications for slurry seal.

427.3.04 Fabrication

General Provisions 101 through 150.

427.3.05 Construction

A. Observe Weather Limitations Do not apply slurry seal if the pavement or ambient temperature is 55 °F (13 °C) or below and falling. If both the ambient and pavement temperatures are 45 °F (7 °C) or above and rising, the slurry seal may be applied. If the relative humidity exceeds 80 percent or the weather is overcast, the Engineer will determine when to apply the slurry seal. B. Apply Tack Coat Before placing the slurry seal, apply a bituminous tack coat consisting of one-part emulsion and three parts water to the old surface as follows: 1. Apply a tack coat with the same asphalt emulsion type and grade as used in the slurry seal. 2. Apply the tack coat according to Section 413. 3. Apply the tack coat with an asphalt distributor. 4. Apply the tack coat at a rate of 0.05 to 0.10 gal/yd² (0.23 to 0.46 L/m²) of the diluted emulsion. The Engineer will determine the exact application rate. C. Prepare the Mix Prepare the mix as follows: 1. Thoroughly mix the material proportions approved for use. Do not mix for more than four minutes. 2. Adjust the amount of water or mineral filler to reach the desired consistency. 3. If the proper slurry consistency cannot be maintained, stop the work and correct the problem by changing the proportions or material sources. D. Apply the Slurry Seal Place the slurry seal uniformly across the width of the traffic lane unless otherwise specified or directed by a Special Provision in the proposal or the Engineer. Carry enough slurry seal in the spreader to completely cover the surface. Apply the slurry seal as follows: 1. Adjust the squeegee action to permit the mix to flow freely and leave a smooth surface. 2. If local conditions require, pre-wet the surface with water by fogging ahead of the slurry box. Closely control pre-wetting to prevent water runoff or puddling. 3. Do not deposit slurry mixture that is not the desired consistency. 4. After depositing the slurry, do not add additional elements. 5. Prevent the following: • Lumping, balling, or unmixed aggregate • Segregation of the emulsion and aggregate fines from the coarse aggregate • Excessive buildup or unsightly appearance on longitudinal or transverse joints 6. If the coarse aggregate settles to the bottom of the mix, remove the slurry from the pavement. 7. Place longitudinal joints on two-lane roadways as close to the center of the pavement as possible. If the roadway has more than two lanes of traffic, place the longitudinal joints as close as possible to where traffic stripes will be placed. E. Apply by Hand Use approved squeegees to spread slurry in areas that are not accessible to the slurry spreader. Do not leave uns ightly marks from the hand work. F. Control Traffic Do not allow traffic on the slurry seal until it has cured enough to withstand marring and tearing, and until no water will be pumped to the surface. Control traffic as necessary to prevent damage to the slurry. Repair any traffic d amage to the slurry seal at the Contractor’s expense. G. Observe Seasonal Limitations Apply slurry seal between the dates given in the Table below. The dates are given by zones shown on the Georgia G eographic Map, below. The Engineer shall authorize any exceptions. Zones Dates 1 April 15 – October 1 2 April 10 – October 25 3 April 1 – October 31 4 April 1 – October 31 G eorgia Department of Transportation Geographical Map For Surface Treatment and Slurry Seal

427.3.06 Quality Acceptance

General Provisions 101 through 150.

427.3.07 Contractor Warranty and Maintenance

General Provisions 101 through 150.

427.4 Measurement

Emulsified asphalt slurry seal is measured by the square yard (meter) complete in place and accepted. The lengths and widths to compute square yards (meters) are specified in Section 109. Diluted emulsified tack coat is measured and paid for according to Section 413.

427.4.01 Limits

General Provisions 101 through 150. South Carolina Florida Alabama Atlantic Ocean North Carolina Tennessee

427.5 Payment

Emulsified asphalt slurry seal is paid for at the full Contract Price per square yard (meter) and is full compensation for furnishing materials, including bituminous materials, equipment, work, and labor. Payment will be made under: Item No. 427 Emulsified asphalt slurry seal type ___ stone, Group II Per square yard (meter)

427.5.01 Adjustments

General Provisions 101 through 150.