Water is the most destructive element of pavement, and crackfilling is the number one way to prevent water intrusion into asphalt surfaces. Effective crackfilling keeps water from entering and weakening the base or sub-base of the pavement. It helps preserve the asphalt 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 prevents problems from spreading and doubles the life of the pavement. Pavement repair in early stages of deterioration pay big dividends later delaying costly resurfacing. C & R Asphalt is equipped with both “low pressure” crackfill and gravity fed machines to meet every customer’s need.
Reflective cracks happen when an existing crack or joint in the underlying pavement structure reflects upward through the surface. Reflective cracks are primarily in resurfacing projects, but low severity cracks can occur in new pavement. Reflective cracking shortens the service life of overlays on asphalt and concrete pavement. These can also be caused by excess ground movement in winter freeze/thaw or summer drought conditions.
This type of cracking usually starts from a singular crack and over time with no crackfill, allows water penetration into subbase. This softens the subbase and cause the asphalt to flex more than design, which creates more cracks adjoining the original. Over time, they get more numerous and crack within themselves. They are usually square or slightly rectangular shape. These cracks cannot be crackfilled. They should be removed, rebased and repaved to original depth.
Edge cracks appear parallel to and within 18 inches of the edge of the asphalt. Causes include poor base, lack of shoulder support and excessive usage at very edge of asphalt, poor drainage, or frost action (ground movement).
Pavement “joints” are created during initial construction when the edges of two pavement mats are placed next to each other. 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 are usually arc-shaped and caused by traffic that is stopping, turning, or climbing a hill or stopping at an intersection. Stresses cause a bond failure between the upper and lower pavement layers. The open end of the arc-shaped crack always points in the direction of the applied force.
Sometimes, it is necessary to rout (widen or open more). This process is mostly used in heavy traffic areas. It cannot be used in cracks that have been crackfilled before. This process widens or opens the crack areas to help in adhesion of the crackfill.
CRACKFILL APPLICATION PROCESS
The crackfilling process begins with properly preparing the crack prior to filling. There are a few methods used to clean cracks of debris, such as vegetation, loose rock, dirt and dust. Some of these methods include an air compressor, steel wire brush or router. A clean, dry surface is important to achieve proper adhesion for the crackfill.
Once clean, cracks can be filled with either a hot or cold rubberized crack filler. Cold crackfillers are primarily used for minimal cracks, while hot pour materials are used for more excessive cracking and applied using pour pots or fire kettle machines.
How the material is applied is oftentimes as important as determining what material will be used. When filling the crack, it’s important to fill from the bottom up to assure a complete seal. Having an experienced contractor complete this type of work is imperative to the success of this type of preventative maintenance.