Maintenance | Washington Asphalt Pavement Association (2023)

Pavement Maintenance describes all the methods and techniques used to extend the life of pavements by slowing their rate of deterioration. The performance of a pavement is directly related to the timing, type and quality of maintenance it receives.

crack sealing

Crack sealing products are used to fill individual cracks in sidewalks to prevent the entry of water or other incompressible substances such as sand, dirt, rocks or brush (Figures 1 and 2). Sealants are mainly used for early longitudinal cracks, transverse cracks, reflective cracks and massive cracks. Fatigue cracks are often too extensive to be filled with crack sealants; they often require treatment of the area, such as patching or reconstruction.

Figure 1: Crack sealing

Figure 2: Sealing cracks

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WAPA Pavement Crack Sealing Considerations

Crack sealing is best done in moderate temperatures (spring or fall) and is most effective if done immediately after cracks appear. Cracks must be routed and cleaned before crack sealant is applied.

fog seal

A fog seal (Figure 3) is the light application of a retarded dilute asphalt emulsion over an aged (rusty) pavement surface. Fog seals are low cost and used to restore flexibility to existing HMA pavements. They may be able to temporarily defer the need for BST or unstructured coverage.

Figure 3 - Parking lot showing fog seal on right

WAPA pavement illustration on fog stamp
Fog seals are suitable for low traffic roads that may be closed to traffic for 4-6 hours, where the slow setting asphalt emulsion breaks down and sets. Application rates that are too high will result in a thin layer of asphalt forming over the original HMA pavement. This layer can be very soft and result in reduced slip resistance. Sand should be reserved to dry over-applied areas.

mud seal

The grout seal is a mixture of emulsified asphalt, water, finely graded fine powderAdd toand mineral fillers for a creamy, runny appearance when applied. Grout sealing is used to fill pavement imperfections, as a preliminary treatment to other maintenance treatments or as a wear process. Micropavement is an advanced form of asphalt slurry that uses the same basic ingredients (emulsified asphalt, water,Add toand mineral fillers) and combine them with advanced polymer additives.

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WAPA Pavement Considerations for Grout Seals

A grout seal is not recommended for at least the first 6 months after laying a new floor. Covering new pavement with grout sealer too quickly may not give the underlying pavement enough time to set and harden.

Bituminous Surface Treatment (BST)

An asphalt surface treatment (figure ), also known as a gravel sealer, is a thin protective wear surface applied to a pavement or base course. BST can provide all the following functions:

  • Waterproof layer to protect the road below.
  • Greater slip resistance.
  • Filler for existing cracks or worn surfaces.
  • Anti-glare surface for wet weather and increased reflective surface for night driving.

Figure 4: Vantage’s bituminous surface treatment (BST), also known as chip seal

WAPA Pavement PrecautionsBST

BST is used more frequently in Eastern Washington than in Western Washington because traffic volumes are generally lower and the periods of predictable good weather that BST requires to achieve satisfactory results are more frequent in Eastern Washington. However, Western Washington uses BST (for example, the city of Seattle has a BST program).

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unstructured coverage

Nonstructural overlays do not involve extensive structural design and typically contribute little, if any, to the pavement's structural capacity. Nonstructural overlays are typically thin surface overlays of 0.5 to 1.5 inches used for (NAPA 1995):

  • Improve driving stability.
  • Correct surface defects.
  • Improve safety features such as anti-skid andsewer system.
  • Improve appearance.
  • Reduce road tire noise.

Nonstructural overlaps can be flexibly classified according to traffic characteristics (NAPA, 1995):

  1. Light/Residential Transportation. The main objective in light traffic areas is to delay the aging of the underlying pavement asphalt binder. due to heavy trafficloadNot much of a concern, mulches are generally less stiff (resulting in more workable combinations, greater durability and flexibility, and the potential for the mulch to recover in traffic situations) and use smaller aggregates.
  2. heavy highway traffic.The main goal in high speed and heavy traffic areas is to prevent rutting and provide good friction. Therefore, these overlays typically use larger angles.Add toand more durable mixes like SMA or OGFC.

WAPA Thin Pavement Considerations

Thin-layer pavements, such as those seen in nonstructural overlays, present several construction problems (NAPA 1995):

  • Thin elevations require less HMA per foot of road length than thick elevations. This can cause paver speeds to be too high (over 70 ft/min), making it difficult for the rollers to keep up.
  • The thin layer will cool down quickly. This results in very little time (sometimes as little as 3-5 minutes) available for compaction before the thin layer reaches the stopping temperature.
  • Slender lifting structures increase screed wear. If the lift depth is less than approximately twice the maximum aggregate size, the HMA may tear under the paver's screed. Very thin layers (less than 1 inch) may be damaged if large particles are dragged across the screed.
  • Lean lifts are more sensitive to vibration sway. Improper selection of amplitude, frequency or roller speed can cause aggregate breakage and damage the bond between the overlay and the existing pavement.
  • Density control is difficult. Thin layers provide fewer options for the rearrangement of aggregate particles under compaction. Therefore, the layer density will tend to be non-uniform compared to the layer density associated with thicker layers. If the payment is in any way tied to the density of the carpet, this should be recognized.


Patches are a common way to treat areas of localized discomfort. Patches can be partial or full depth, but HMA pavement patches are usually full depth. High-quality HMA patches can be considered permanent fixes, although many patches are emergency fixes in harsh conditions (e.g. cold, rain) and are therefore only considered temporary fixes. The patch material can be almost any HMA or cold mix asphalt material, as well as some types of grout. Some form of hot melt adhesive is usually used for permanent repairs, while cold mix is ​​often used for emergency temporary repairs.

WAPA Pavement Precautionscold mix asphalt

Cold mix asphalt is a mixture of bitumen or other proprietary bituminous binder product aggregate and emulsion. After mixing, the water in the emulsion evaporates, leaving the bitumen-covered aggregate ready for use. It is called "cold mix" because, unlike hot mix asphalt (HMA), cold mix asphalt is mixed, transported and placed at near ambient temperatures. Cold mix asphalt is often used as a temporary repair material because, while it will not provide the long-term performance of HMA, it can be laid without HMA's stringent quality controls.

pothole repair

Pothole patching (Figures 5 and 6) has probably received the most public attention. Pothole patching covers a wide range of methods and intents, from permanent full-depth patching to temporary on-the-fly patching. However, potholes are the result of pavement failures, so any fixes are considered temporary until the root cause is identified and corrected. Two common fixes are described below.

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Figure 5: Semi-permanent Pothole Repair

Figure 6 - Same bump fixed a year later, still running fine

Semi-permanent pothole patches (see Figures 5 and 6) (FHWA 1998)

  1. Remove all water and debris from potholes.
  2. Line up the sides of the pothole so they are perpendicular and have undamaged pavement on all sides.
  3. Place the restorative material into the clean square hole. Material should be stacked in the center and tapered towards the edges so as to be flush with the edge of the surrounding pavement.
  4. Compact the patch material starting from the center and working towards the edges. Compaction can be accomplished with a vibratory plate compactor or a single-drum vibratory roller. Check the compacted patch material for slight bumps. This is done so that subsequent traffic loads compress it to the height of the surrounding road surface.

Toss and Roll (FHWA 1998)

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  1. Put the patching material into the pothole without any preparation or water/debris removal.
  2. Use patch truck tires to compact patch material (typically 4 to 8 passes).
  3. Check the compacted patch for slight crowning. If there is a dent, add more repair material and compact.

While it may appear that the semi-permanent technique would produce a higher quality patch than the cast-roll technique, FHWA's Long-Term Paving Performance (LTPP) study found, "The cast-roll technique has been shown to be as effective as the cast-roll technique." semi-permanent procedures for those materials" (FHWA 1998). Since the semi-permanent technique requires more labor and materials, if the materials are of higher quality for use.


What is the routine maintenance of asphalt pavement? ›

A proper pavement maintenance program includes crack filling, pothole repair, sealcoating, and many other surface applications, depending on the condition of the pavement. It should also include sweeping and periodic line striping.

What is the difference between rap and ras asphalt? ›

While RAP is 95 to 96 percent aggregate, RAS is only 70 to 80 percent aggregate and the rest being a stiff asphalt formulated for roofing standards.

What does RAS stand for in asphalt? ›


What is the rule of 90 asphalt? ›

A rule of thumb to differentiate the polymer modified binder from unmodified binder is to add both low and high temperature grades together, if the sum is greater than 90, it is likely to be a polymer modified binder.

What are examples of pavement maintenance? ›

6 Types of Road Maintenance
  • Asphalt Overlays. Asphalt overlays restore roads to a smooth condition. ...
  • Patching. Patching is the process of filling potholes or excavated areas in the asphalt pavement. ...
  • Reshaping. This is necessary when a road surface it too damaged to be smoothed. ...
  • Slab Replacement. ...
  • Smoothing. ...
  • Reconstruction.
May 31, 2018

What are the types of pavement maintenance? ›

Preventative, corrective and emergency maintenance are all part of a comprehensive asphalt pavement maintenance program. Proactively planning preventive maintenance is the best way to prevent costly corrective or emergency maintenance.

What are 3 types of asphalt? ›

There are three main types of asphalt: Hot Asphalt, MC Cold Mix, and UPM. There are also different varieties of these asphalts for summer and winter use.

What does ABC stand for in asphalt? ›

Introduction. Asphalt pavement, brick and concrete (ABC) rubble, such as the rubble generated by the demolition of buildings, bridges or roadways, must be handled in accordance with the Massachusetts solid waste regulations.

What grade of asphalt is best? ›

The 60-70 grade is usually used only in pavements where traffic is very heavy such as principle city streets and very heavily trafficked rural highways. The second grade, 85-100, is by far the most widely used material for plant mixes and is suitable for most pavements.

What does ATB mean in asphalt? ›

Asphalt treated base (ATB) consists of a compacted course of base material which has been weatherproofed and stabilized by treatment with an asphalt binder.

What does Rtfo stand for in asphalt? ›

The Rolling Thin-Film Oven (RTFO) procedure (Figure 1) provides simulated short term aged asphalt binder for physical property testing. Asphalt binder is exposed to elevated temperatures to simulate manufacturing and placement aging.

What does PCC stand for in asphalt? ›

Portland Cement Concrete (PCC) Resurfacing. 1.02 DESCRIPTION OF WORK. A. Includes the requirements for the construction of full depth Portland Cement Concrete (PCC) pavement, pavement widening, and concrete curbs and gutters placed upon a prepared or corrected subgrade or previously constructed base or subbase.

What temperature does asphalt stop compacting? ›

Asphalt Mix Temperature

If the mix falls below 185 degrees, it becomes too rigid to properly compact over the paving surface.

What is the maximum asphalt slope? ›

The Asphalt Institute recommends a transverse slope of between 1.5 to 3.0% on all pavement surfaces, and an even steeper slope of 3 to 6% on shoulders.

What is the void ratio of asphalt? ›

The allowable percentage of air voids (in laboratory specimens) is between 2.0 percent and 4.0 percent for most surface course mixes or as required by the owner. The durability of an asphalt pavement is a function of the air-void content.

What is the lifespan of pavement? ›

A well-constructed asphalt pavement that experiences low levels of traffic can last 25 years or more.

How many years does pavement last? ›

High-quality asphalt pavement can last an average of 15 to 20 years with the right care and maintenance. The freeze and thaw cycles of the area along with the type of soil underneath the base stone are main factors in the lifespan of the pavement.

What are the four major components in such pavement? ›

A typical flexible pavement consists of four components: Soil subgrade, sub-base course, base course, and surface course respectively.

What is asphalt maintenance? ›

Asphalt maintenance is crucial to maximizing the service life of your pavement. Routine maintenance slows the deterioration of your pavement by protecting it from its “Natural Enemies,” sun, air and water.

What are the two types of pavements? ›

There are two main types of road surfaces and pavement construction methods: rigid pavement (consisting of one layer) and flexible pavement (typically made up of multiple layers).

What is the difference between pavement and asphalt? ›

Asphalt is a dark-colored, gritty material that is often used for driveways and parking lots. Pavement, on the other hand, can be brightly colored with distinctive patterns and designs. In addition, asphalt is generally thicker than pavement and contains gravel particles that aid drainage and traction.

What are the basics of asphalt? ›

Asphalt is a sticky, black, and highly viscous liquid. It's thick and borders on being a solid itself. In asphalt paving it's used as the glue, or binder mixed with aggregate particles to create asphalt concrete. Asphalt pavement is generally composed of 5% asphalt and 95% aggregates, like stone, sand, and gravel.

What is Type 7 top asphalt? ›

Type 7 asphalt contains fine stone and dust which has a very smooth finish. Type 6 asphalt contains slightly larger stone, so it provides more strength but is not quite as smooth as Type 7. Once Sealcoated it is difficult to distinguish the difference in the textures.

What does SBS mean in asphalt? ›

What is SBS? Styrene-butadiene-styrene (SBS) is a class of polymers commonly used worldwide since the 1970s to enhance asphalt binder performance in the paving and roofing industries. The styrene and butadiene monomers, chemical precursors, are arranged in blocks of polystyrene and polybutadiene.

What is 404 asphalt? ›

Item 404-LVT is a mix that is rich in asphalt binder, fine textured, nonrestrictive in aggregate shape and type, with restrictive RAP limits. It can be placed in a thin layer of 1 inch for economy.

What does HMA stand for in asphalt? ›

Hot Mix Asphalt 101. Page 2. Definition of HMA. In simple terms…: A mixture of asphalt binder and.

Is blacktop the same as asphalt? ›

Simply put, blacktop is a type of asphalt. That being said, the difference between the two stems from the same ingredients being mixed differently, as well as in their preparation process. These two different processes are dictated by the difference in usage.

What is the maximum asphalt thickness? ›

When static steel-wheeled rollers are used, the maximum lift thickness that can be properly compacted is 3 inches. When pneumatic or vibratory rollers are used, the maximum thickness of lift that can be compacted is almost unlimited. Generally, lift thicknesses are limited to 6 or 8 inches.

What is blacktop called? ›

Asphalt concrete (commonly called asphalt, blacktop, or pavement in North America, and tarmac or bitumen macadam in the United Kingdom and the Republic of Ireland) is a composite material commonly used to surface roads, parking lots, airports, and the core of embankment dams.

What does ss1 mean in asphalt? ›

SS-1 is an anionic slow setting asphalt emulsion primarily used as a tack coat - typically providing that "glue" to bond an existing base pavement layer to a newly applied layer.

Is thicker asphalt better? ›

Unlike with concrete, where thickness means strength and weight-resistance, thicker is not necessarily better when it comes to asphalt paving. Far more important is the thickness and compaction of the underlying sub-base.

What is PMB in asphalt? ›

PMB consists of bitumen blended with a synthetic polymer or crumb rubber. PMBs are used to enhance the performance of binders on heavily trafficked or distressed pavement surfaces, often in adverse climatic conditions.

What is leftover asphalt called? ›

Crushed asphalt is recycled pavement. It's leftover material that's been crushed and ground down to be reused. This crushed asphalt is also sometimes referred to as reclaimed asphalt pavement (RAP), asphalt millings, or pavement millings.

What is reused asphalt called? ›

Reclaimed asphalt pavement (RAP) is the term given to removed and/or reprocessed pavement materials containing asphalt and aggregates. These materials are generated when asphalt pavements are removed for reconstruction, resurfacing, or to obtain access to buried utilities.

What is the difference between SMA and HMA asphalt? ›

SMA is generally more expensive than a typical dense-graded HMA because it requires more durable aggregates, higher asphalt content, modified asphalt binder and fibers. In the right situations it is cost-effective because of its increased rut resistance and improved durability.

What CSI code is asphalt? ›

Division 32 covers two general categories of site improvements - pavement and landscaping. Pavement subtopics address the complete construction process for asphalt, concrete and unit paving.

What does AC pavement mean? ›

Asphalt concrete (AC) is a standard Type B asphalt concrete mixed, spread and compacted as noted in the Caltrans standards.

What is HMA in pavement design? ›

Hot mix asphalt (HMA) is known by many different names, such as hot mix, asphalt concrete, asphalt or blacktop. It is a combination of stone, sand or gravel bound together by asphalt cement. After it is mixed at a high temperature, laid and compacted, the result is an improved driving surface for the traveling public.

How hot is asphalt when it is 100 degrees outside? ›

On a sunny day, asphalt can quickly heat up, even if the air temperature doesn't feel super hot to you. For example, if it's 85 degrees, then the blacktop temperature is 110. If the air temperature is over 100 degrees, then the blacktop can reach 160 degrees.

How thick should asphalt be before compaction? ›

Compaction and Thickness—A general rule of thumb is 4 inches for driveways and 6 inches for car parking lots (after compaction). To ensure consistent asphalt thickness, the sub-grade must be fine-graded and compacted prior to placing the asphalt.

Can you compact asphalt too much? ›

Over-compacting can cause the pavement to segregate and become This can lead to premature cracks and failure. Insufficient compaction can result in raveling of the pavement. This is when the asphalt mix begins to separate, and the aggregate components detach from the mix.

What grade is too steep for a driveway? ›

How Steep of a Driveway Is Too Steep? You shouldn't have a driveway slope grade greater than 20%, but ideally, it shouldn't go over 12%. What that means is the incline shouldn't be higher than 12 feet for every 100 feet of length. A high slope grade presents all sorts of problems.

What is the steepest road grade allowed? ›

Percent grade actually overstates our natural inclination to think of steepness in terms of degrees. That six percent grade on the Interstate? It�s an incline of only three and a half degrees. Six percent, by the way, is the maximum allowable grade on an Interstate highway.

What is the minimum drainage slope for asphalt? ›

As a rule of thumb, typically minimum grades of 1 percent for asphalt surfaces and 0.5 percent for concrete surfaces are recommended.

What causes low VMA in asphalt? ›

VMA in a mix will typically drop when going from mix design to production. This is because there is more aggregate breakdown and dust generated in an asphalt plant relative to the mix design process.

What causes low air voids in asphalt? ›

As a result of the compaction process, the asphalt-coated aggregate particles in the mix are forced closer together, which increases the amount of aggregate interlock and interparticle friction and also reduces the air void content of the mix.

How do you reduce air voids in asphalt? ›

Filler reduces the air voids and increases the density of the compacted mixture. For each filler content, the higher the density of the mix, the lower the percentage of voids in the mix, and vice versa. This means that the densification of asphalt mixtures is influenced by filler content.

How often should you coat asphalt? ›

Asphalt sealcoating is every two to three years depending on how much traffic your driveway gets or how constantly it is being exposed to the elements such as UV rays, snow and other chemicals.

How do you care for a newly paved asphalt driveway? ›

Avoid driving on new asphalt initially.

You may drive over your driveway after 2 days, but do not park on it for 5 days and possibly longer in hotter temperatures. Even after the blacktop has cured, do not expect it to be as hard as concrete. Your new blacktop will soften and harden as temperatures rise and fall.

What is the routine road maintenance? ›

Routine road maintenance means preservation, including road repairs and resurfacing, but does not include road construction or penetration of existing grade; Sample 1.

What is pavement preventive maintenance? ›

Preventive maintenance: consists of planned activities to extend pavement life for pavements in good condition. Surface treatments are applied globally to a pavement to seal the surface. This will prevent water infiltration, slow down oxidation and aging and stabilise loose surface materials.

Why is asphalt maintenance important? ›

Damaged asphalt pavement is a serious safety hazard to drivers and pedestrians. This puts drivers at a higher risk of accidents. Cracks and potholes can damage tires, the underside of vehicles, and cause pedestrians to trip and tumble. The next benefit of asphalt maintenance is that it keeps people safe.

What is the best time of year to seal asphalt? ›

Spring Is The Best Time To Seal Coat Your Asphalt

While we still recommend those with cracks developing try to get their asphalt seal coated before it gets too cold, spring is really the best time for seal coating.

Should you seal asphalt every year? ›

How often should I seal coat my driveway? Industry standards recommend every two years; allowing the sealer to wear away before you reseal the driveway.

What time of year is best for asphalt? ›

Summertime is when paving season is in full swing. The dry weather, long hours of sunshine, and high nighttime temperatures offer the best environment for the new asphalt to properly cure. Early fall can also be a great time for your paving project, but better to get started sooner rather than later.

What not to do on new asphalt? ›

Don't park in the same spot during the first 6-12 months while your driveway or parking lot is curing. Do not turn your steering wheel back and forth when your car is not moving. Take your time pulling in and out of the driveway or parking lot, as not to scar the asphalt pavement. 4.

Should you spray water on new asphalt driveway? ›

Your new asphalt driveway will soften and harden as temperatures rise and fall. Watering down your driveway with a hose on hot days will temporarily harden the asphalt. This is helpful, but not mandatory.

Is it good to seal a new asphalt driveway? ›

For brand-new driveways, it's imperative to sealcoat it after 90 days or when the asphalt is hardened and fully cured. The ideal time to sealing your driveway is in the summer or when the temperature reaches at least 50 degrees Fahrenheit.

What is major maintenance? ›

Major Maintenance refers to renovation and repair of building components and systems, as defined in this section.

What is surface maintenance? ›

WHAT IS SURFACE MAINTENANCE? Road surface maintenance is the periodic re-shaping of the road surface to ensure proper drainage and smooth traffic passage.


1. Asphalt Paving Surface Preparation
(PA Asphalt Pavement Association)
2. Common Pavement Maintenance Techniques 5.19.20
(Cornell Local Roads Program)
3. Perpetual Pavements: How to Design a Road to Last
(National Asphalt Pavement Association)
4. No Distractions - Lives are on the Line
5. The Use and Success of Asphalt Perpetual Pavements
(Tom Clayton)
6. Principles of Asphalt Pavement | April 12, 2023 at Galuppi's
(ACE by TSK)


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