What do they use to fill in cracks in the road?

Asphalt roads develop cracks over time due to factors like weather, heavy loads, and ground movement. Filling these cracks is important for maintaining the integrity of the road surface and preventing further damage. There are a few main materials used to fill cracks in asphalt roads:

Asphalt Crack Filler

Asphalt crack filler, also known as joint sealant, is a viscous material that is poured or squeezed into cracks and then leveled off. It helps prevent water from seeping into cracks and causing potholes or other deterioration. Asphalt crack filler comes in different grades with different melting points to suit various climates. Hot pour crack fillers that melt around 300°F are commonly used for moderate to hot climates, while cold pour asphalt crack fillers are better suited for cooler climates.

Types of Asphalt Crack Fillers

Some common types of asphalt crack filler include:

  • Asphalt emulsion – A mixture of asphalt, emulsifying agents, and water
  • Cutback asphalt – Asphalt cement diluted with petroleum solvents
  • Asphalt cement – Pure (undiluted) asphalt binder

Asphalt emulsion and cutback asphalt are fluid at ambient temperatures, making them easy to pour into cracks. They solidify as the water or solvents evaporate. Asphalt cement needs to be heated to high temperatures before pouring.

Advantages of Asphalt Crack Filler

Using asphalt crack filler has these advantages:

  • Seals out water to prevent potholes and further cracking
  • Durable material similar to original asphalt pavement
  • Relatively low cost compared to road repairs
  • Quick and easy application without specialized equipment

Rubberized Asphalt

Rubberized asphalt uses crumb rubber from recycled tires as an additive. The rubber helps make the asphalt more flexible and better able to withstand cracking. Rubberized asphalt filler is applied hot just like regular asphalt crack filler. The rubber additive allows it to flex rather than crack as the road surface expands and contracts with temperature changes.

Advantages of Rubberized Asphalt

Benefits of using rubberized asphalt include:

  • Very durable crack filler
  • Withstands weathering and deformation
  • Can be used to resurface old cracked pavement
  • Recycles scrap tires, reducing waste

Polymer-Modified Asphalt

Polymer-modified asphalt uses plastic polymers like ethylene vinyl acetate to improve the performance of the asphalt binder. The polymers increase the asphalt’s viscosity and flexibility so it can resist cracking. Polymer-modified asphalt filler provides excellent adhesion in cold temperatures. It is more expensive than standard asphalt crack filler but offers improved durability.

Advantages of Polymer-Modified Asphalt

Polymer-modified asphalt offers these benefits:

  • Excellent flexibility and crack resistance
  • Good weathering performance
  • Durable; lasts longer than standard asphalt filler
  • Easy to apply hot or cold

Portland Cement Crack Filler

Portland cement crack filler uses a mortar or grout material to fill cracks in concrete and asphalt roads. Portland cement, sand, and water are mixed together into a wet paste and then pressed into cracks with a trowel or pouring pot. The material dries hard to form a permanent concrete filler.

Advantages of Portland Cement Crack Filler

Portland cement crack filler has these advantages:

  • Low cost material
  • Bonds well for long lasting repairs
  • Can be used for filling concrete or asphalt cracks
  • Fast drying for quick repairs

The main drawback is that portland cement is rigid when dry and more prone to cracking than flexible asphalt fillers.

Polyurethane Crack Filler

Polyurethane is a two-part liquid plastic that expands as it cures to bond tightly in cracks. The two liquid components (isocyanate and resin) are mixed together, poured into cracks, and react to form tough, rubbery polyurethane. Polyurethane crack fillers are suitable for flexible filling of cracks up to 1 inch wide.

Advantages of Polyurethane Crack Filler

Polyurethane offers these benefits:

  • Expands and bonds extremely well to cracks
  • Cures rigid enough to support traffic
  • Flexible, won’t become brittle and crack
  • Resists weathering and deformation

Epoxy Crack Filler

Epoxy crack fillers contain two epoxy resin components that react after mixing to harden into a strong, adhesive material. The cured epoxy binds tightly to the edges of a crack for structural repairs. Epoxy fillers are ideal for tight cracks less than 1/4 inch wide.

Advantages of Epoxy Crack Filler

Epoxy crack filler provides these advantages:

  • Exceptional bonding strength and durability
  • Cures hard and withstands deformation
  • Effective waterproofing
  • Can be used on many materials including concrete, steel, asphalt, masonry, wood, etc.

Factors Affecting Crack Filler Selection

Some key considerations when selecting a road crack filler include:

  • Crack width – Narrow cracks less than 1/4 inch wide are best treated with epoxy. Wide cracks over 1 inch can be filled with polyurethane or rubberized asphalt.
  • Road surface material – Portland cement fillers work for concrete roads while asphalt fillers are better for asphalt pavement. Epoxies bond well to multiple surfaces.
  • Climate – Cold pour fillers like asphalt emulsion work better in cool climates. Hot pour works better in warm climates.
  • Cost – Asphalt fillers are generally the most economical while epoxies and polyurethanes cost more.
  • Performance requirements – Epoxies and polyurethanes provide the highest performance for durability and water resistance.

Crack Filling Equipment

Some common equipment used for filling road cracks includes:

  • Pressure sprayer – For spraying liquid asphalt emulsion into cracks
  • Wand attachment – For squeezing hot pour from a tank into cracks
  • Pour pot – For pouring liquid filler into wide cracks
  • Road router – For widening and cleaning cracks prior to filling
  • Hot air lance – For drying damp cracks before filling
  • Squeegee or trowel – For smoothing and leveling poured filler

Many municipalities and contractors use specialized crack filling machines or kettle rigs that heat and agitate the filler for easy pouring. These machines allow efficient crack filling without frequent reheating breaks.

Crack Filling Best Practices

Some best practices for effective road crack filling include:

  • Cleaning cracks thoroughly using a router or compressed air
  • Choosing the appropriate filler for the crack size and road surface
  • Following manufacturer mixing and heating specifications
  • Filling cracks flush to the road surface, without overfilling
  • Allowing proper curing time before opening to traffic
  • Routing out old or failed filler, then refilling for permanent repairs

Proper preparation, filler selection, and installation technique help ensure long lasting road crack repairs.

Crack Filling Schedule

Cracks should be monitored and filled according to the following general schedule:

Crack Width Filling Interval
Hairline cracks (<1/8 inch) 5-7 years
Narrow cracks (1/8 – 1/2 inch) 3-5 years
Wide cracks (>1/2 inch) 1-2 years

Higher traffic roads require more frequent crack filling than low volume roads. Cracks should also be filled more often in cold climates subject to freeze-thaw cycles.

Cost to Fill Road Cracks

Crack filling costs range from $0.25 – $1.00 per linear foot depending on crack width and depth. Deeper cracks and wider cracks cost more to fill. Other cost factors include:

  • Filler material – Asphalt emulsion is lowest cost. Epoxies are more expensive.
  • Surface type – Asphalt is cheaper than concrete.
  • Equipment rental – Kettle rigs may add $500 – $1500 per day.
  • Location – Urban busy roads cost more for traffic control.
  • Contractor rates – Vary by region and company size.

For a 2-lane road with moderate cracking, costs can range from $1000 – $5000 per mile. Crack filling represents a cost-effective maintenance activity that extends the life of roads.


Filling road cracks with the appropriate material prevents water intrusion and deterioration in asphalt and concrete pavement. Asphalt fillers like rubberized, polymer-modified and emulsion products provide the right balance of flexibility and weather resistance at a reasonable cost. More rigid fillers like Portland cement and epoxies work well in certain applications. Proper crack filling technique and scheduling is key to preventing potholes and other pavement damage on roads.

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