Hot Crackfilling

Crackfilling is used as a first defense against pavement deterioration because it offers several important benefits. Effective crackfilling keeps water from entering and weakening the base or sub-base. It helps preserve the pavement adjacent to the cracks; prevents sand, stone, and dirt from making its way into open cracks causing compressive stresses; and extends pavement life by minimizing crack growth.

Proper attention to cracks will prevent problems from spreading and extends the life of the pavement. Pavement repair in the early stages of deterioration will pay big dividends later by delaying costly resurfacing.

Crack Types

Reflective Cracks	Block Cracks	Edge Cracks

Reflective Cracks

This type of crack appears primarily in resurfacing projects, although it can also occur in a new pavement. It happens when an existing crack or joint in the underlying pavement structure reflects upward through the surface.

Block Cracks

Visually, this type of cracking forms a square pattern, with cracks intersecting each other at nearly right angles. A common cause of this on parking lots is lack of traffic, (steady traffic constantly kneads the pavement and keeps it flexible). Other causes include excessive air voids, low-penetration asphalt, or an overly high plant mix temperature.

Edge Cracks

Unlike the previous types, edge cracks appear only parallel to and within 18 inches of the edge of the pavement. Causes include poor base, lack of shoulder support, poor drainage, or frost action.

Joint Cracks	Slippage Cracks	Alligator Cracks

Joint Cracks

Pavement "joints" are created during initial construction when the edges of two pavement mats are placed next to one another. These constructed joints usually have a lower density of asphalt than that of the surrounding pavement. If the mats don't bond properly (for a variety of reasons), joint cracks appear.

Slippage Cracks

Slippage cracks are usually crescent-shaped and caused by heavy traffic that is stopping, turning, or climbing a hill. Resultant stresses cause a bond failure between the upper and lower pavement layers. The open end of the U-shaped crack always points in the direction of the applied force.

Fatigue or Alligator Cracks

Over time, a flexible asphalt pavement becomes more rigid and is less able to tolerate vertical deflections. This causes tension in the pavement and results in alligator-type cracking. Such cracking can also occur from structural inadequacy, aging, and oxidation.

It is generally recommended that alligator areas be removed and replaced rather than filled or sealed.

Crack Routing

In some cases, crack widening or routing is necessary. Crack routing creates a proper reservoir to which the crack sealant material adheres. Crack sealant works best inside cracks, specifically because it stays flexible.

A properly sealed crack or joint will remain sealed and provide the desired protection year round. The crack sealant must be flexible enough to stretch with the winter contractions, remain bonded to the crack interfaces and offer the strength and resiliency necessary to resist cohesive failure.