EXPERT ADVICE
BENEFITS AND LIMITATIONS OF CRACKSEALING
The go-to solution extends pavement life and prevents problems By Jeff Winke
T he superstition has many people avoiding stepping on cracks . Early folk beliefs held that cracks were not something to trifle with because danger lurked in these empty spaces . The cracks signal gaps in the boundaries between the earthly realm and the metaphysical realm .
As an old schoolyard rhyme cautioned : “ Step on a crack , break your mother ’ s back .” Fortunately , mothers ’ backs have remained intact , when the absent minded to the malicious have stepped on pavement cracks .
However , for asphalt pavement pros , cracks represent a very real danger . They indicate a pavement failure caused by the penetration of weather-related moisture or too much weight atop the pavement . Whether water or load related causes , cracks are unsightly , dangerous , and costly . As asphalt pavement problems develop , they become increasingly dangerous to drive on and become even more costly to repair if not immediately fixed .
Several different types of cracks can develop in asphalt pavements .
• Fatigue cracking or alligator cracking due to the interconnected cracks which resemble an alligator ’ s skin is caused by load-related deterioration resulting from a weakened base course or subgrade , too little pavement thickness , overloading , or a combination of these factors .
• Block cracking is a series of large ( typically one foot or more ), rectangular cracks on an asphalt pavement surface .
Typically , block cracking covers large areas and can happen in areas where there is no traffic . The cause is shrinkage of the asphalt pavement due to temperature cycles .
• Edge cracks are longitudinal cracks which occur within a couple feet of the outer edge of a pavement . These cracks form because of a lack of support at the pavement edge .
• Longitudinal cracks happen near the centerline of the pavement . Typical causes : a poorly constructed joint , shrinkage of the asphalt layer , cracks reflecting up from an underlying layer , and longitudinal segregation due to improper paver operation . These cracks are not load-related . www . callape . com [ 20 ] 1.800.210.5923