What causes the asphalt to crack?

Asphalt can crack due to multiple reasons. The most common cause is the oxidation that occurs due to the sun’s ultraviolet rays. The uv light drys out the liquid asphalt binder, which in turn causes the pavement to lose flexibility. As the pavement shrinks and expands throughout the day, cracks begin to form on the surface. Moisture is another factor. As it penetrates under the asphalt surface it can freeze and thaw during the winter months. Once this problem arises it ran rapidly begin the deterioration process and form potholes, which will require additional repairs.

Types of asphalt cracks we can repair

FATIGUE Also known as alligator cracking. Repetitive passing of overweight vehicles stress the pavement due to poor quality construction or inadequate pavement thickness.
BLOCK This is a combination of both longitudinal and transverse cracks. These are typically found in low traffic areas.
EDGE Edge cracks are formed from a lack of support at the pavement edge. They are found running the length of the road within one or two feet of the edge of the pavement.
SLIPPAGE A poor bond of pavement layers is the main cause with this type of crack. They often appear in areas where vehicles brake, turn, and accelerate.
REFLECTION This is a crack that forms as a result of underlying pavement movement from an asphalt overlay or cracks in a concrete foundation.
TRANSVERSE These are cracks caused by low temperatures that shrink the HMA layer. Generally they run perpendicular to the roadway.
LONGITUDINAL This type runs along the length of the roadway. They often form at the joint between adjacent lanes or at the edge of high traffic wheel paths. Improper compaction during construction is a cause of this type.

The most common reason for pavement failure is moisture penetrating the surface

Cracks in pavements allow moisture to penetrate the surface which causes pavement material failure. Failure to seal cracks results in further cracking, potholes and eventually a major pavement breakdown, leading to unnecessary expensive repairs.

To minimise the water infiltrating the pavement base, crack sealing with a hot polymer/rubberised bitumen sealant is required, preventing future pavement problems.

Crack sealing is an extremely economical way of maintaining pavements.  It is very cheap and effective when compared to undertaking other more extensive works such as resurfacing and reconstructing.

Crack sealing is a practical and cost effective measure and is part of any good pavement management program for all roads.

Early intervention is vital in prolonging the life of pavements. Once you can see pavement failure on the surface, the rate of deterioration accelerates. Crack sealing is a key element in early intervention as it slows the deterioration process and can significantly add to the life of a pavement, maximizing your asphalt investment

Crack Sealing Applications

Scraper Finish
Used on smooth asphalt, reducing noise and improving skid resistance

Bead Pouring
Used on chip seal surfaces to ensure better penetration into cracks

Over banding
Used on wide cracking to provide sufficient bondage on either side of the crack

The key qualities of crack sealing products are their flexibility, suitability to local weather conditions and that they are applied hot and are skid resistant.
An effective crack sealant must have excellent torsional recovery within the crack, withstanding repeated expansion and contractions in the pavement. This flexibility must exist over a wide range of temperatures and have a high softening point to ensure that the product will not bleed in hot conditions.

When overlaying existing asphalt, it is vitally important to crack seal prior to works to prevent reflective cracking. If new asphalt is laid on failed pavement, the cracks in the base will undermine the new overlay and produce new cracks.