ASTM D6690
Hot-Applied Pavement Joint Sealant
Last updated: April 19, 2026
Overview
ASTM D6690, Standard Specification for Joint and Crack Sealants, Hot Applied, for Concrete and Asphalt Pavements, is the primary performance specification for hot-poured rubberized-asphalt sealants used on portland cement concrete (PCC) pavement joints, asphalt pavement cracks, and the longitudinal joints between PCC and asphalt. It consolidates and replaces the older AASHTO M 301 family of specifications and is the standard most state DOT pavement specifications now reference.
D6690 covers four product types (Type I through Type IV), each tied to a different climate or fuel-exposure scenario. Selecting the right type is a function of pavement service temperature range, joint movement, traffic loading, and whether the surface will see fuel spillage. The standard sets minimum requirements for resilience, cone penetration, flow, bond, and ductility, and prescribes the laboratory test methods used to qualify a sealant for each type.
The legacy designation AASHTO M 324 (formerly the parallel AASHTO spec) is still cited in older state spec books and contract documents. AASHTO M 324 has been harmonized with ASTM D6690, so a sealant qualified to one is generally accepted under the other; project specifications should be read carefully when both are referenced. The FHWA Pavement Preservation Compendium treats hot-applied D6690 sealants as a core preservation tool for both PCC joint resealing and asphalt crack sealing.
D6690 vs cold-applied silicone: D6690 is the hot-poured side of the pavement-sealant decision. The cold-applied single-component silicone alternative is governed by ASTM D5893. The two are not interchangeable on a single project; they are chosen based on climate, traffic-opening time, and equipment available.
Scope and Types I-IV
D6690 applies to single-component sealants that are heated in a jacketed melter and poured into a prepared joint or routed crack. The standard does not cover cold-applied sealants, preformed compression seals, or chemically curing materials. Within the hot-applied family it defines four types, distinguished primarily by climate severity and chemical resistance.
| Type | Intended Service | Distinguishing Test |
|---|---|---|
| Type I | General use in mild to moderate climates; PCC and asphalt joints and cracks where extreme low-temperature ductility is not required. | Bond at 0°F (50% extension) |
| Type II | Cold-climate service; pavement subject to sustained subfreezing temperatures and large seasonal joint movement. | Bond at -20°F (50% extension) |
| Type III | Severe-climate / high-movement service; northern-tier highways and airfields where deep frost and large slabs drive joint movement beyond Type II range. | Bond at -20°F (200% extension, three cycles) |
| Type IV | Fuel-resistant service; pavement exposed to jet fuel, gasoline, or diesel spillage (military airfield aprons, fueling areas, fuel islands, hardstands). | Fuel-immersion resistance test in addition to Type I bond |
Type designations are not strictly hierarchical. A Type III sealant qualifies the same low-temperature bond as Type II at a more demanding extension, and is generally acceptable wherever Type II is specified. Type IV is a separate branch: its qualifying property is fuel resistance, and Type IV products are not automatically substitutable for Type II or III in cold-climate joints unless the data sheet documents the low-temperature bond.
Performance Requirements
D6690 sets minimum thresholds for five core properties, each measured by a referenced ASTM test method. Manufacturer technical data sheets typically list the as-tested values alongside the specification minimum so a specifier can confirm conformance.
Cone Penetration (ASTM D5329)
Measures sealant softness at 77°F (25°C) by allowing a standard cone to sink into the cured material for five seconds under a fixed load. Lower penetration indicates a stiffer, more rut-resistant sealant.
- Type I, II, IV: maximum 90 (units of 0.1 mm)
- Type III: maximum 130 (slightly softer, to support higher movement capability)
Flow (ASTM D5329)
Measures slumping when a cured sealant specimen is held vertically at 140°F (60°C) for five hours. Limits sag in joints exposed to summer pavement temperatures.
- Maximum flow: 3 mm for all types
- Failure mode: track marks, bleeding into wheel paths, flush sealant lost to traffic
Resilience (ASTM D5329)
Measures the percentage rebound of a cured specimen after a controlled compression. Higher resilience indicates the sealant will return to shape after a passing wheel load and after seasonal joint compression.
- Minimum resilience: 60% for all types
- Drives long-term tracking, indentation, and stone-pickup behavior
Bond / Ductility (ASTM D5329, mortar block specimen)
The single most important field-correlated property. Cured sealant is bonded between two mortar blocks, conditioned to the test temperature, and stretched in cycles. Pass criterion is no crack greater than 1/4 in. depth in the sealant or at the bond line.
- Type I: 50% extension at 0°F, three cycles
- Type II: 50% extension at -20°F, three cycles
- Type III: 200% extension at -20°F, three cycles
- Type IV: 50% extension at 0°F, three cycles, plus fuel-immersion
Asphalt Compatibility / Fuel Resistance
For Type IV, the sealant is immersed in a reference fuel and re-tested for bond and weight loss. For all types, sealants placed in asphalt pavement must be compatible with the binder so the sealant does not soften or bleed into surrounding pavement.
Application Temperature Limits
Hot-applied sealants are heated in a jacketed, agitated, oil-bath melter and dispensed through a heated wand or pour pot. Two temperatures govern the work: the manufacturer's Safe Heating Temperature (SHT) and Pour Temperature (PT). Operating outside the published window damages the sealant before it reaches the joint.
| Temperature | Typical Range | What It Controls |
|---|---|---|
| Pour Temperature (PT) | 360 to 390°F (182 to 199°C) typical | Viscosity at the wand; flow into the joint reservoir |
| Safe Heating Temp (SHT) | 400 to 410°F (204 to 210°C) typical | Maximum melter setpoint; exceeding it scorches the binder and ruins resilience and bond |
| Pavement Surface Temp | Above 40°F (4°C) ascending; verify with manufacturer | Determines whether the sealant skins before bonding to the joint wall |
Critical: Always pull the SHT and PT from the specific product's published technical data sheet rather than a generic range. Two D6690 Type II products from different manufacturers can have pour-temperature windows that do not overlap. Overheating beyond the published SHT permanently degrades the sealant; specifications typically require melter records or thermometer logs to confirm compliance.
Application also requires clean, dry, frost-free joint walls. Most spec books require sandblasting or hot-air-lance preparation for resealing work, and prohibit application onto damp substrates. Traffic opening temperatures are product-specific; many D6690 sealants can accept traffic once the surface temperature drops below 90°F (32°C), but the manufacturer's data sheet governs.
Common Spec Language
Sample specification paragraphs that appear in state DOT and federal contract documents. Adapt the type designation and reference standard to the project's climate and surface use.
PCC Joint Resealing, Moderate Climate:
"Joint sealant shall be a single-component, hot-applied, rubberized-asphalt sealant conforming to ASTM D6690, Type I. Sealant shall be heated and applied in accordance with the manufacturer's published Safe Heating Temperature and Pour Temperature limits. Contractor shall maintain melter temperature records for the duration of the work."
Northern-Tier Highway, Cold Climate:
"Joint and crack sealant shall conform to ASTM D6690, Type II (or Type III where shown on plans). Sealant shall be approved from the Department's Qualified Products List. Joint walls shall be sandblasted, blown clean with oil-free compressed air, and dry at the time of sealing."
Airfield / Fuel-Resistant Service:
"Joint sealant for fueling apron, hardstand, and fuel-island pavement shall conform to ASTM D6690, Type IV (jet-fuel resistant). All other airfield pavement joints shall conform to ASTM D6690, Type II or III as specified for the climate region."
Older agency specifications may reference AASHTO M 324, AASHTO M 301, Federal Specification SS-S-1401C, or ASTM D3405 in lieu of D6690. These legacy callouts are generally satisfied by D6690-qualified products of the equivalent type, but the specifier should confirm the current cross-reference language used by the contracting agency.
Selection by Climate Zone
Choosing between Type I, II, III, and IV is primarily a climate and surface-use decision. The table below summarizes the conventional selection logic used in pavement preservation programs and in the FHWA Pavement Preservation Compendium guidance for hot-applied sealants.
| Climate / Use | Recommended Type | Notes |
|---|---|---|
| Mild to moderate (Sun Belt, mid-Atlantic, Pacific coastal); winter lows above 0°F | Type I | Cost-effective baseline; adequate bond performance for most highway and parking applications |
| Cold climate, regular subfreezing winters (Midwest, mountain west) | Type II | Most-specified type by northern-tier state DOTs; -20°F bond test maps to typical PCC slab movement |
| Severe climate / high-movement (deep frost, long slabs, heavily jointed PCC airfields) | Type III | Reserved for joints where calculated movement exceeds Type II range; commands a price premium |
| Fuel exposure (airfield fuel islands, military hardstands, depot fueling lanes) | Type IV | Use in defined fuel-spill zones only; outside those zones revert to Type II or III for the climate |
| Asphalt crack sealing (random and longitudinal cracks) | Type I or II per climate | Crack-sealing programs typically pick the same type used for adjacent PCC joint work |
When to step away from D6690: Hot-applied sealants cure quickly and tolerate immediate traffic, which makes them the default for high-volume pavement. For PCC joints in extreme service where long-term bond is more important than rapid traffic opening, a cold-applied silicone qualified to ASTM D5893 may be specified instead. For wider joints with predictable, small movement, a preformed compression seal can outlast either poured option. A cross-system comparison appears in the upcoming Highway & Pavement Joint Sealant Guide.
Frequently Asked Questions
How is ASTM D6690 different from the old AASHTO M 301?
AASHTO M 301 was an older, narrower hot-poured sealant specification that was effectively superseded by AASHTO M 324, which in turn was harmonized with ASTM D6690. The current generation of state DOT spec books references D6690 (or M 324) for hot-applied joint and crack sealants. A sealant qualified to D6690 of the appropriate type will generally satisfy a contract that still cites M 301 by name, but the contracting agency should confirm acceptance in writing for the project's pay items.
When is Type IV (jet-fuel resistant) actually required?
Type IV is intended for pavement areas with regular exposure to jet fuel, gasoline, or diesel: fueling aprons and hardstands, fuel islands, defueling pads, and military depot pavement. It is not required for general airfield taxiways or runways outside fueling zones, and it is not a substitute for Type II or III in cold climates because its qualifying property is fuel immersion resistance rather than low-temperature ductility. On a single airfield project it is common to see Type IV called for inside fuel-spill zones and Type II or III everywhere else.
Can D6690 sealants overlap saw-cut joints onto the adjacent slab?
D6690 itself addresses the in-joint sealant performance, not the overband geometry. Many state DOTs allow a thin overband (commonly 2 to 4 in. wide, 1/8 in. thick) over PCC joints and asphalt cracks, while others require a flush or recessed configuration. An overband does provide an additional water shed and bond perimeter, but it can be tracked or picked up in hot weather or under heavy braking. Overband products specifically formulated for asphalt crack treatment are governed by ASTM D7116 rather than D6690; on asphalt overband programs, verify which standard the spec actually requires.
What is the recommended kettle (melter) temperature for D6690 sealants?
There is no single number. Each D6690 product publishes its own Safe Heating Temperature (SHT) and Pour Temperature (PT), typically in the 360 to 410°F range. The melter setpoint must stay at or below the SHT, and material is dispensed when it falls within the PT band. Use a jacketed, agitated, oil-bath melter; direct-fired kettles can scorch the binder and void the warranty. Most agencies require the contractor to keep temperature logs, and over-temperature material is treated as non-conforming and discarded.
What is the difference between ASTM D6690 and ASTM D7116?
D6690 covers hot-applied sealants intended to live inside the joint or crack reservoir on PCC and asphalt pavement. ASTM D7116 covers hot-applied sealants for asphalt overband crack treatment, where the material is intentionally placed on the pavement surface to bridge and waterproof a crack. The two standards have different viscosity, softening point, and tracking-resistance criteria. A D6690 Type II product is not automatically suitable as an overband, and a D7116 overband product is not automatically a good in-joint sealant. Crack sealing programs that mix the two strategies must specify each material separately.
Compliant Products
US Made Supply is building out a brand-neutral catalog of D6690-qualified hot-applied joint and crack sealants. If you are sourcing Type I, II, III, or IV material for a state DOT, FAA, military, or municipal pavement project and need pricing, Buy America documentation, or Qualified Products List confirmation, reach our sourcing team at partnerships@usmadesupply.com. Specify the type, the climate zone or agency QPL the project requires, estimated quantity in pounds or boxes, and the application equipment available so we can match a product family that fits the work.
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