| 1.0 |
Scope
This guideline covers the components and methods of installation of polyurethane base mat sandwich system track surfaces. The polyurethane base mat sandwich system is a homogenous blend of SBR rubber granules and polyurethane binder base layer spread evenly in a monolithic application followed by sealing. The sealant layer is a massive application of polyurethane coating with colored EPDM granules broadcast or encapsulated into the coating. This sealant layer makes the system impermeable. The system is a resilient all weather surface. It is textured and is used in both indoor and outdoor applications.
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| 2.0 |
Materials
A variety of products may be used in the construction of the track surface. The terms defined below are to clarify the language used in this guideline and in proprietary specifications.
| A. |
Primer
The primer is a mixture of polyurethane binder and a viscosity reduction vehicle that allows for a light film application.
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| B. |
Polyurethane
The polyurethane binder is a single component, 100% solids, moisture cure, elastic pre-polymer, designed to bind rubber granules together.
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| C. |
Polyurethane Coating and Sealers
Two component 100% solids polyurethane coating consisting of a Part A colored polyol and a Part B isocyanate activator. Specific gravity of 1.15 to 1.30. The coating may be used for the top layer as well as the sealant layer.
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| D. |
Polyurethane Sealer
Two component 100% solids thioxtropic polyurethane coating consisting of a Part A colored polyol and Part B isocyanate activator. Specific gravity of 1.45 -1.60. The coating is applied without the adding of rubber dust and is used only as a sealer.
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| E. |
Polyurethane Aliphatic Top Coating
A single or two component aliphatic top coating applied to structural surfaces that need to be protected from UV degradation.
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| F. |
SBR/EPDM Black Rubber
Fully cured rubber granules that may either be ambient or cryogenically ground from post-industrial by-products to a size of not less than 1 nor more than 4mm. The general cut of the granules should be cubicle. They should contain less than 4% dust and be free of foreign debris. They should not contain any other color within the granule.
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| G. |
Colored EPDM Rubber
Colored EPDM granules should be ground from fully cured virgin slabs of peroxide- or sulfur-cured rubber (the curing process must be compatible with the polyurethane chemicals being used). The EPDM content should be not less than 20%. The general cut of the granules should be cubicle and they should contain less than 4% dust. Colored EPDM rubber dust graded to 0.0 -0.5 may be used as a thickener for the polyurethane coating in the sealing process.
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| 3.0 |
Surface Specifications
Surface specifications should include:
Color
Depth
Type of facility:
Governing Body, International Properties or Competition Properties
Events to be Marked
Surface properties for consideration:
Flatness and Imperfections Thickness
Modified Vertical Deformation; Force Reduction
Friction; Wet Spike Resistance
Tensile Properties; Elongation
Weathering Color
Flammability
Testing Methods
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| 4.0 |
Thickness, Weight and Specific Gravity
Each surface system should be at least 1/2” (12.5mm) in total thickness to allow for variation in the underlayment and to prevent spiked shoes from penetrating to the base layer, potentially disrupting the bond. The total weight of the system is contingent upon the depth of the surface and the specific gravity of the materials. Both SBR and EPDM rubber particles will vary in specific gravity and bulk density value of rubber. This coupled with the application methods, shape and size will affect the rubber required to achieve 1/2” thickness. The chart below is intended for guidance.
Per 1/8"
| Color/Type |
Size/Shape |
Specific Gravity |
Shore A Hardness |
Lbs./Sq.Yd. |
| Black SBR |
1-4mm Granules |
1.15-1.40 |
55-70 |
3.6-4.1 |
| Black EPDM |
1-4mm Granules |
1.20-1.50 |
55-70 |
3.8-4.5 |
| Colored EPDM |
1-4mm Granules |
1.40-1.60 |
55-70 |
4.5-4.9 |
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| 5.0 |
Installed Materials
The installation contractor should provide the owner with a manifest listing the quantities of materials to be used for surfacing in the following format:
Base Layer
(____) lbs. of primer (____) number of drums (____) weight/drum
(____) lbs. of binder (____) number of drums (____) weight/drum
(____) lbs. of rubber (____) number of bags (____) weight/bag
Seal Layer
(_____) lbs. coating Part A (_____) no. of drums (_____) weight/drum
(_____) lbs. coating Part B (_____) no. of drums (_____) weight/drum
Is coating thixotropic? Yes No
(_____) lbs. of binder (_____) number of drums (_____) weight/drum
(_____) lbs. of EPDM dust (_____) no. of drums (_____) weight/drum
Top Layer (A)
(_____) lbs. coating Part A (_____) no. of drums (_____) weight/drum
(_____) lbs. coating Part B (_____) no. of drums (_____) weight/drum
(_____) lbs. of colored EPDM (_____) no. of bags (_____) weight/bag
Size of EPDM granules
Top Layer (B)
(_____) lbs. coating Part A (_____) no. of drums (_____) weight/drum
(_____) lbs. coating Part B (_____) no. of drums (_____) weight/drum
(_____) lbs. of colored EPDM (_____) no. of bags (_____) weight/bag
Size of EPDM granules
Aliphatic Layer (when applicable)
(_____) lbs. coating Part A (_____) no. of drums (_____) weight/drum
(_____) lbs. coating Part B (_____) no. of drums (_____)weight/drum
(_____) lbs. 1 component (_____) no. of drums (_____) weight/drum
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| 6.0 |
Material Delivery
All materials should be delivered to the job site in labeled and marked containers. Quantities needed to complete the project in accordance with the manufacturer’s specifications should be verified. All materials should be located to allow for work to proceed without interruption.
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| 7.0 |
Installation Equipment
All installation equipment including mixers, pavers, sprayers and hand tools should be kept free of moisture while in use. They should be cleaned daily. No equipment or vehicles used in the installation process should leak any gas, petroleum products, solvents, etc.
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| 8.0 |
Surface Preparation
The asphalt or concrete base should be sufficiently cured and cleaned in order for work to progress. Recommended cure times - 14 days for asphalt, 28 days for concrete.
Prior to installation of the track surface system, the entire base should be checked for planarity and surface tolerance. Any areas that vary +/- 1/4” when measured with a 10’ straightedge in any direction should be patched with a compound compatible with the base material and approved by the manufacturer of the track surfacing system. After patching, the surface should not allow water to stand greater than 1/16” deep one hour after rain has ended.
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| 9.0 |
Installation
| A. |
Primer
The surface should be primed with the appropriate polyurethane primer using spray equipment or rollers. Application rates range between 0.18 - 0.27 lbs. per square yard. For an asphalt base, primer application may be reduced by the contractor when extreme heat conditions soften the asphalt. Some manufacturer’s systems will not require a primer. |
| B. |
Mixing
The rubber granules and polyurethane binder should be accurately measured and placed in a clean dry mixer and mixed until all granules are thoroughly coated with the polyurethane binder. No evidence of water may exist during the mixing process. The mixing ratio of rubber to binder should not be less than 5 parts rubber to 1 part binder as determined by the weight of the products. The pot life of the mix should not be less than 45 minutes. No agents are to be added to extend pot life.
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| C. |
Placement of Base Mat
The prepared material is placed evenly in front of the paving machine. The machine should be operated at a speed and with the screed bar at an angle to provide a tight and smooth surface, free of chatter marks and voids. The screed bars are to be constantly heated and should oscillate. The power source may be either electric or fuel generated. Material should be placed at the specified depth in a single application and allowed to cure.
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| D. |
Trowel Work
All seams are to be troweled smooth within the pot life of the material. All edges should be straight and rounded by turning the trowel. All cold dry seams should be cut straight at an inward angle and primed prior to commencing with subsequent work.
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| E. |
Arid Climates
To aid in the curing process in arid climates, it may be necessary to mist the surface with water upon completion of the day’s work.
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| F. |
Seal Coat
The seal coat is a mixture of the two component coating and EPDM rubber dust that is mixed and squeegee-applied to the base mat. Alternatives are to squeegee-apply two component thixotropic polyurethane coating without rubber dust or spray binder and brush EPDM rubber dust into the base mat. In all cases, sufficient material is to be applied to render the surface impermeable. It is extremely important that the base mat and base are completely void of moisture before commencing with application of the seal coat.
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| G. |
Top Coat
| 1. |
The top coat is a massive flow application of the two component coating that is mixed according to the ratios of part A and B listed by the manufacturer. The material is to be self leveling and should be free of ridges. Prior to initial set, colored EPDM rubber granules are broadcast with sufficient excess granules being applied to assist in the embedding process. Normally 5 to 5.5 lbs. of granules per square yard will be embedded. All loose excess granules are removed after initial cure.
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| 2. |
The alternative top coating is a spray application of a two component coating and encapsulated EPDM rubber granules applied at an approximate ratio of 60% coating to 40% rubber to sufficiently protect the base.
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| H. |
Aliphatic Top Coating
If the encapsulated top coating is unprotected for UV resistance, then a thin mil layer of one or two component aliphatic top coating should be spray-applied, normally in two applications, over the surface in accordance to the manufacturer’s recommendation.
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| I. |
Line Markings
The surface system manufacturer must approve the type and brand of marking paint used. All lane and event markings should be in accordance with the applicable governing body.
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| 10.0 |
Cautions
| A. |
All packaging and excess materials must be disposed of in accordance with state, local and federal standards and regulations.
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| B. |
Do not allow liquid binders to freeze.
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| C. |
Resilient surfacing systems will not resolve inadequacies in the base or asphalt mix.
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| D. |
This guideline does not cover proper subbase and base construction or drainage considerations. The success of any surface is dependent upon a properly constructed base and good drainage. |
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See also ASBA Guidelines for: |
I.A.
I.B.
I.C.
I.D.
I.E.
III.A.
III.B.
III.I.
III.J. |
General Conditions for Construction
Site Investigation
Site Preparation, Earthwork, Drainage and Subbase Construction
Vegetation Control or Vegetation Regrowth Prevention
Subsurface and Surface Drainage for Recreational Areas
Basic Layout, Dimensions & Site Considerations for Track Construction
Hot Mix Asphaltic Concrete Construction or III.C. Concrete Construction
Drawings
Quantitative Analysis of Installed Track Surfaces |
