Transverse and Longitudinal cracking Repairs
Transverse cracking
Transverse cracking, or cracks that occur across the pavement surface about perpendicular to the parking lot center, are often caused by the asphalt expansion and contraction due to temperature changes and or this movement due to asphalt aging. Initially, these cracks will be relatively equally spaced depending on traffic but will eventually become more prevalent in the parking lot or roadway. In some cases, as these cracks become more prevalent, block cracking forms where the Transverse cracks develop into squares throughout the pavement. Also, these cracks may extend either entirely or partially across the pavement area or roadway. Transverse cracks begin as "hairline" cracks - or cracks up to ¼" wide - but will widen to ½" or wider with age and lack of proper repair. Because these cracks are allowing water into the pavement base and subgrade, lack of proper repair or maintenance will lead to more cracks developing parallel to the original transverse cracking. If not properly repaired, these transverse cracks will be appear with greater prevalence and the cracks will become wider; eventually, the cracks will be so prevalent that entire areas will be broken or "alligatored" (see Alligatoring section) leading to a more serious, cutting and patching repair.
Longitudinal cracking
Longitudinal cracking, or cracks that form down the center of the pavement surface or roadway, usually develop due to the deterioration of longitudinal joints formed by separate passes of an asphalt paving machine. When the parking lot is constructed, the paving machine must make separate passes which form two lanes of asphalt; joints develop between these two lanes because this is usually the least dense areas of pavement and is not properly compacted. These cracks are fundamentally the same as Transverse cracks, despite their difference in orientation, and also allow water, salts, engine oils and other harmful substances into the base and subgrade. These substances lead to more cracks in the pavement and eventual pavement failure around the original Longitudinal cracks. Usually Longitudinal cracks follow the same type of size development as Transverse cracks: starting as hairline or about ¼" cracks then developing to larger, more serious problems; eventually, without proper repair and maintenance, Longitudinal cracks will become more prevalent and areas, leading to cutting and patching necessity. Block cracks also form from Longitudinal cracks.
Repairs
Before cracks become so prevalent that cutting and patching is necessary, cracks between ¼" and 1" wide can be filled or sealed with poly-fiber reinforced crackfill. First, these cracks are cleaned with blown air or grazing wheel to remove debris, grass, old failed crackfill and other substances from the crack. Then, the reinforced crackfill or sealant is applied at temperatures in excess of 375o. After the crackfill has been applied to the cracks, then Black Beauty is added to ensure proper adhesion to the pavement surface and prevention of failure due to surface temperatures and/or traffic.
NOTE
: In the event of especially hot surface temperatures, crackfill has a tendency to become rubbery when driven or stepped on. As long as the material does not lift away from the pavement, this is a normal occurrence and should not be investigated further. If the material lifts, this could be Cracksealing Deficiency and should be investigated.
