Asphalt Rubber Slurry Surfacing

Polymer modified slurry seal is used in the same applications as a standard slurry seal however polymer slurry seal has higher binder cohesion that leads to improvements in resistance to raveling, especially in cul-de-sacs. Polymer modified slurry seals are more abrasion resistant and can be laid at higher application rates without bleeding or deformation. For airport application suitable variations are made- including rolling.

1.01 SCOPE Slurry Seal shall consist of mixing asphalt emulsion, aggregate, and water and spreading the mixture on a surface or pavement where shown on the plans, as specified in these specifications and the special provisions, and as directed by the Engineer.

2.01 MATERIALS The materials for slurry seal immediately prior to mixing shall conform to the following requirements:

2.02 (a) POLYMER MODIFIED ASPHALT EMULSION WITH CARBON BLACK DISPERSION AND DISPERSED ASPHALT RUBBER.
The base polymer emulsified asphalt shall be a quick traffic, quick cure (QT-QC) type, shall be a homogeneous brown color throughout and show no separation after thorough mixing, shall break and set on the aggregate within five (5) minutes and shall be ready for cross-traffic within fifteen (15) to forty five (45) minutes. The polymer asphalt emulsion, upon standing undisturbed for a period of twenty-four (24) hours, shall show no white or milky colored substance on its surface and conform to the requirements in Table I.

TABLE I
Test on Emulsion	Method of Test	Requirement
Viscosity, SSF, @ 77 degrees F, sec	ASTM D244	15-90
pH		1 to 3
Distillation Residue %, Minimum		60
Test on Residue from Distillation Test
Penetration, 77 degrees F., 100g, 5s	ASTM D5	40-80
Softening Point (Ring & Ball), degrees F	ASTM	130 +
Ductility, 77 degrees. F,(25C, 5 cm/Min., Minimum	ASTM D113	25
Fraass-Breaking Point (degrees C.) min.	DIN 52012	-18

Carbon black dispersion compatible with the emulsion shall be added by suitable blending ( in line or propeller mixing) to the emulsion at the plant before use. The carbon black at 30% solids by weight shall be added at 6-8% on emulsion total weight.

A dispersion of asphalt rubber - RG-1 or equivalent - shall be blended in line with the emulsion at the plant and the emulsion remixed before use.

This shall be added at 5-8% based on emulsion total weight.

The emulsion shall be mixed by circulation or other method before pumping into the slurry truck.

2.02 (b) WATER Water shall be potable, free of harmful soluble salts and shall be of such quality that the asphalt will not separate from the emulsion before the slurry seal is in place in the work.

2.02 (c) AGGREGATE Aggregate shall consist of sound, durable, crushed stone or crushed gravel and approved mineral filler. The material shall be free from vegetable matter and other deleterious substances. Aggregates shall be 100% crushed with no rounded particles. The percentage composition by weight of the aggregate shall conform to the following grading:

Percentage Passing
Sieve Sizes	Type II
3/8"(9.5- mm)	100
No. 4(4.75- mm)	90-100
No. 8(2.36- mm)	65-90
No. 16(1.18- mm)	40-70
No. 30(600- um)	25-50
o. 200 (75- um)	N5-15
Theoretical asphalt content, % based on dry aggregate	7.5-13.5
Approximate application rate (Pounds/Square Yard)	14-18

The aggregate shall also conform to the following quality requirements:

Test	Method of Test	Requirement
Sand Equivalent or ASTM D2419	California Method 217	60 Min.
Durability Index	California Method 229	55 Min.

2.02 (d) POLYMER
Styrene Butadiene Rubber latex polymer shall be added to the water/soap phase by injection prior to the mill manufacture of the asphalt emulsion by the emulsion producer. The polymer shall be BASF NX 1118 or approved equal. The amount of polymer solids shall be between 3 and 4 percent of the asphalt residual content and shall be certified by the emulsion producer on each load of emulsion delivered to the job site. No post or field addition of polymer will be allowed. Samples of polymer shall be provided and shall conform to the following requirements.

Test	Requirement
Total Solids, min %	60
Bound Styrene %	24 - 60
pH at 25 Degrees C	4.2 - 5.2
Brookfield Viscosity RVT	1000 - 4000
Residual Monomer %	0.08 max.

2.02 (e) MINERAL FILLER
The mineral filler shall be either Portland Cement or other approved mineral fillers, if required. Portland Cement if used, shall be commercially available Type I-II and shall be free of lumps and clods.

2.03 MIX DESIGN
At least 7 working day before slurry seal placement commences, the Contractor shall submit to the Engineer for approval a laboratory report of tests and proposed mix design covering the specific materials to be used on the project. The percentage of asphalt emulsion proposed in the mix design shall be within the percentage range specified in Section 2.04 "Proportioning."

The tests and mix design shall be performed by a laboratory capable of performing the applicable International Slurry Seal Association (ISSA) tests. The proposed slurry seal mixture shall conform to the requirements specified when tested in accordance with the following tests:

Test	ISSA Test Method	Requirement
Slurry Seal Consistency, cm	T106	3 max.
Wet Stripping	T114	Pass
Compatibility	T115	Pass (a)
Cohesion Test, kg - cm within 1 hour	T139	20 min. (b)
Wet Track Abrasion, g/sq..ft.	T100	75 max.

Immediately before commencing the slurry seal operations, all surface metal utility covers (including survey monuments) shall be protected by thoroughly covering the surface with an appropriate adhesive and paper or plastic. No adhesive material shall be permitted to cover, seal or fill the joint between the frame and cover of the structure. Covers are to be uncovered and cleaned of slurry material by the end of the same work day.

Hand tools shall be available in order to remove spillage. Ridges or bumps in the finished surface will not be permitted. The mixture shall be uniform and homogeneous after spreading on the existing surface and shall not show separation of the emulsion and aggregate after setting.

Adequate means shall be provided to protect the slurry seal from damage from traffic until such time that the mixture has cured sufficiently so that the slurry seal will not adhere to and be picked up by the tires of the vehicles.

For the purpose of this project, the construction zone is defined to include all stockpile staging areas and travel routes to/from streets where the slurry seal is to be applied.

The Contractor shall abide, at all times, to the State of California, Department of Transportation's "Manual of Traffic Controls for Construction and Maintenance Work Zones" as applicable to this project.

Any deviations shall not be made without prior written approval from the project engineer.

2.07 MEASUREMENT
Slurry seal will be measured and paid for by the square yard for the actual surface areas covered.

2.08 PAYMENT The contract price paid per square yard for slurry seal shall include full compensation for furnishing all labor, materials, tools, equipment and incidentals and for doing all the work involved in the furnishing and placing of the slurry seal complete in place, including cleaning the surface and protecting the slurry seal until it has set, all as shown on the plans, as specified in these specifications and as directed by the Engineer.

Last Updated (Wednesday, 09 December 2009 14:08)

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Asphalt Rubber Slurry Surfacing