Alligator Cracking

arrest CRACKING AN INTRODUCTION - Crocodile shot, also called fatigue catch or alligator cracking, is a leafy vegetable type of distress in mineral pitch paving. Crocodile cracking is characterized by interconnecting or interlaced cracking in the asphalt bottom resembling the hide of a crocodile. Cell coats plenty vary in size up to 300 millimetres (12in) across, but are typically less than cl millimetres (5. 9in) across. Crocodile cracking is generally a loading failure, but many factors can contribute to it. It is ofttimes a sign of sub- group failure, paltry drainpipe, or repeated over-loadings.It is important to prevent crocodile cracking, and vivify as soon as contingent, as advanced cases can be very costly to repair and can lead to formation of potholes or premature paving material failure. CAUSES OF gator CRACKING - * Crocodile cracking is an asphalt pavement distress most often instigated by failure of the develop due to traffic loading. * Crocodile cracking can be greatly influenced by environmental and other establishs man traffic loading remains the direct ready. Frequently, overloading eliminates because the base or subbase inadequately support the surface layer and subsequently cannot handle piles that it would unremarkably endure. Poor drainage in the avenue bed is a patronise cause of this degradation of the base or subgrade. A heavy inception thaw, similarly to poor drainage, can weaken the base course, leading to crocodile cracking. * husking or raveling is another possible cause of crocodile cracking. Stripping occurs when poor bail bond between asphalt and aggregate al humiliateds the aggregate at the surface to dislodge. If left uncorrected, this reduces the thickness of the pavement, reducing the touched portions ability to carry its intentional loading.This can cause crocodile cracking to develop rapidly, as overloading will happen with loads of less magnitude or frequency. CAUSES OF ALLIGATOR CRACKING - miser y of surface due to loading Stripping of bitumen due to poor adhesion of bitumen asphalt Environmental grooms - (a) Due to excessive rain b) hot suffer (c) frost action CHARACTERISTICS or IDENTIFICATION - * Crocodile cracking manifests itself initially as longitudinal cracking (cracks along the direction of the flow of traffic) in the kick the bucket layer of the asphalt. * These cracks are initially thin and sparsely distributed. If further impairment is allowed, these longitudinal cracks are connected by transverse cracks to form snappy sided, prismatic pieces. * This interlaced cracking pattern resembles the scales on the back of a crocodile or alligator, hence the name, alligator cracking. * More severe cases involve pumping of fines, spalling, and bountiful pieces of pavement. * The most severe cases of crocodile cracking often occur with other pavement distresses, but are exemplified by potholes, large cracks(3/8&8243 or larger), and heavily spalled edges. MEASUREMENT & QUANTIFICATION -There are many different ways to legal profession crocodile cracking, but in general a pavement distress manual or index will be used. For example, the Pavement Condition advocator is widely used to quantify the overall level of distress and condition of a section of thoroughfare. Measurement of crocodile cracking unique(predicate)ally(and pavement distress in general) is prerequisite to determine the overall condition of a road, and for determination of a time-line for rehabilitation and/or repair. There are many other rate systems, and many rating systems currently in use are found on the AASHO Road Test.There are two important criteria to take into effect when measuring crocodile cracking. The first is the extent of the cracking. This is the amount of road surface theater of operations which is affected by this pavement distress. The second criterion is the severity of the cracking. ghastliness, which has been discussed above, refers to how further most the cracking has progressed, and is often directly a function of crack width. Severity whitethorn be rated numerically, or given a rating from low to severe. The rating may be entered into a pavement counseling system, which will suggest a priority and method for the repair.Systems have been positive that detect crocodile and other types of pavement distress automatically. They measure the severity and frequency of alligator cracking on the road-path. One such machine is the road surface profilometer, which is mounted on a vehicle and measures the profile of the road surface while it is moving down the roadway. PREVENTION & location - Preventing crocodile cracking can be as simple as preventing the common causes. Reducing overloading on an asphalt pavement or improving drainage can prevent crocodile cracking in many cases.However, often the particularized cause is fairly difficult to determine, and prevention becomes difficult correspondingly. A skilful strategy to prev ent overloading, which is a main cause of crocodile cracking, is to increase the sense of the asphalt layer. According to certain researchers, pavements of a minimum strength or thickness can hypothetically handle infinitely many loads without showing structural defects, including crocodile (fatigue) cracking. These pavements are called perpetual pavements. When repairing pavement affected by crocodile cracking, the main cause of the distress should be determined. whatever investigation should involve take away a pit or coring the pavement and subbase to determine the pavements structural composition as hale as determining whether or not underground moisture is a contributing factor. The repair needed also differs establish on the severity and extent of the cracking. In the early stages, sealing cracks with crack sealant limits further deterioration of the subgrade due to moisture penetration. Small areas may be repaired by removal of the affected area, and replacement with new base and asphalt surface.Once the damage has progressed, a structural asphalt overlay or complete reconstruction may be necessary. CONCLUSION When repairing pavement affected by crocodile cracking, the main cause of the distress should be determined. However, often the specific cause is fairly difficult to determine, and prevention is therefore correspondingly difficult. Any investigation should involve digging a pit or coring the pavement and sub base to determine the pavements structural makeup as well as determining whether the moisture is a contributing factor.Small areas may be repaired by removal of the affected area, and replacement with new base and asphalt surface. Once the damage has progressed or the affected area is large and extensive, a structural asphalt overlay or complete reconstruction is necessary to ensure structural integrity. If the government also takes necessary action by giving an yardstick of the maximum ESWL that can be allowed, then cracking can be preven ted. However in practical it is not possible always. Our conciousness also plays a great role. If we can understand what can cause cracking and take necessary action, then it can be prevented.