Why Asphalt Pavement Cracks
- Asphalt Pavement Equipment
- Why Asphalt Pavement Cracks Repair
- What Is Asphalt Pavement
- Cracking In Asphalt Pavements
- Pavement Crack Sealers
Preventing and repairing potholes and pavement cracks. By John Davis. They must be easy to apply yet resist cracking, aging and weathering. Also, they must be compatible with asphalt pavement. Asphalt emulsions, asphalt cements and fiberized asphalt are used for crack filling. Asphalt rubber, rubberized asphalt, low-modulus rubberized. Cracks are caused by deterioration of the pavement. Obviously, pavement is best when it is first constructed. As sunlight oxidizes the pavement and seasonal temperature changes expand and contract the pavement, cracks form. Water, impurities, and debris infiltrate the cracks and continue to degrade the pavement and put the pavement’s subbase at risk. Can pavement that has cracks be resurfaced or will it require complete reconstruction? Linear cracks in pavement are fine for resurfacing and do not require complete subgrade reconstruction. We use a paving fabric and sealant under the new asphalt overlay which keeps cracks from causing any problems. Rain enters the cracks and causes base damage. These all contribute to a worn out asphalt pavement and must be stopped before it’s too late. Below is a list of the different types of asphalt deterioration caused by the preceding factors: Cracking – There are many different types of cracking that can occur, and believe it or not they all.
Crocodile cracking, also called alligator cracking and perhaps misleadingly fatigue cracking, is a common type of distress in the wearing courseroad surface. The following is more closely related to fatigue cracking which is characterized by interconnecting or interlaced cracking in the seal layer resembling the hide of a crocodile.[1] Cell sizes can vary in size up to 11.80 inches (300 mm) across, but are typically less than 5.90 inches (150 mm) across. Fatigue cracking is generally a loading failure,[1] but numerous factors can contribute to it. It is often a sign of sub-base failure, poor drainage, or repeated over-loadings. It is important to prevent fatigue cracking, and repair as soon as possible, as advanced cases can be very costly to repair and can lead to formation of potholes or premature pavement failure.
Asphalt Pavement Equipment
It is usually studied under the transportation section of civil engineering.
Causes[edit]
Fatigue cracking is a sealed pavement distress most often instigated by failure of the surface due to traffic loading. However, fatigue cracking can be greatly influenced by environmental and other effects while traffic loading remains the direct cause. Frequently, overloading happens because the base or subbase inadequately support the surface layer and subsequently cannot handle loads that it would normally endure.[2] There are many ways that the subbase or base can be weakened.
Poor drainage in the road bed is a frequent cause of this degradation of the base or subgrade.[1] A heavy spring thaw, similarly to poor drainage, can weaken the base course, leading to fatigue cracking.[1]
Stripping or raveling is another possible cause of fatigue cracking. Stripping occurs when poor adhesion between asphalt and aggregate allows the aggregate at the surface to dislodge. If left uncorrected, this reduces the thickness of the pavement, reducing the affected portion's ability to carry its designed loading.[1] This can cause fatigue cracking to develop rapidly, as overloading will happen with loads of less magnitude or frequency.
Edge cracking is the formation of crescent-shaped cracks near the edge of a road.[3] It is caused by lack of support of the road edge, sometimes due to poorly drained or weak shoulders. If left untreated, additional cracks will form until it resembles fatigue cracking.[3] Like wheel-path fatigue cracking, poor drainage is a main cause of edge cracking, as it weakens the base, which hastens the deterioration of the pavement.[4] Water ponding (a buildup of water which can also be called puddling) happens more frequently near the edge than in the center of the road path, as roads are usually sloped to prevent in-lane ponding. This leads to excess moisture in the shoulders and subbase at the road edge. Edge cracking differs from fatigue cracking in that the cracks form from the top down, where fatigue cracks usually start at the bottom and propagate to the surface.
Development[edit]
Fatigue cracking manifests itself initially as longitudinal cracking (cracks along the direction of the flow of traffic) in the top layer of the seal.[5] These cracks are initially thin and sparsely distributed. If further deterioration is allowed, these longitudinal cracks are connected by transverse cracks to form sharp sided, prismatic pieces. This interlaced cracking pattern resembles the scales on the back of a crocodile or alligator, hence the nickname, crocodile cracking.
Why Asphalt Pavement Cracks Repair
More severe cases involve pumping of fines, spalling, and loose pieces of pavement. The most severe cases of fatigue cracking often occur with other pavement distresses, but are exemplified by: potholes,[1] large cracks(3/8' or larger), and severely spalled edges.[4]
Measurement and quantification[edit]
There are many different ways to measure fatigue cracking, but in general a pavement distress manual or index will be used. For example, the Pavement Condition Index is widely used to quantify the overall level of distress and condition of a section of road. Measurement of fatigue cracking specifically (and pavement distress in general) is necessary to determine the overall condition of a road, and for determination of a time-line for rehabilitation and/or repair. There are many other rating systems, and many rating systems currently in use are based on the AASHO Road Test.
There are two important criteria to take into account when measuring fatigue cracking. The first is the extent of the cracking. This is the amount of road surface area which is affected by this pavement distress. The second criterion is the severity of the cracking.[6] Severity, which has been discussed above, refers to how far the cracking has progressed, and is often directly a function of crack width.[6] Severity may be rated numerically, or given a rating from 'low' to 'severe'. The rating may be entered into a pavement management system, which will suggest a priority and method for the repair.
Systems have been developed that detect fatigue cracking and other types of pavement distress automatically.[7] 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.
What Is Asphalt Pavement
Prevention and repair[edit]
Preventing fatigue cracking can be as simple as preventing the common causes. For example, reducing overloading on a sealed pavement or improving drainage[2] can prevent fatigue cracking in many cases. Prevention primarily depends on designing and constructing the pavement and subbase to support the expected traffic loads, and providing good drainage to keep water out of the subbase.
A good strategy to prevent overloading, which is a main cause of fatigue cracking, is to increase the depth of the seal. According to certain researchers, pavements that exceed a certain minimum strength or thickness can hypothetically handle infinitely many loads without showing structural defects, including fatigue cracking.[1] These pavements are called perpetual pavements or long-term performance pavements (LTPP).
When repairing pavement affected by fatigue 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 subbase to determine the pavement's structural makeup as well as determining whether or not subsurface moisture is a contributing factor.[1] The repair needed also differs based 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.[2] 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. Proper repair may include first sealing cracks with crack sealant, installing paving fabric over a tack coat, or milling the damaged asphalt. An overlay of hot mix asphalt is then placed over the completed repair. [2]
If it was made in China it is a Squier by Fender and not a Fender Telecaster. If the serial number prefix is 'CGF' as you indicated, that is not a Squier by Fender as Squier serial numbers prefixes for China are two letters with the exception of 'CXS' per my references. It's a genuine Fender (whatever that means). 
See also[edit]
Notes[edit]
- ^ abcdefghFlexible Pavement Distresses, Pavement Interactive, date accessed: June 6, 2017
- ^ abcdPASER Asphalt Pavement Manual, Asphalt Pavement Alliance of Michigan, date accessed: June 6, 2017
- ^ abDistress Identification Manual for the Long-Term Pavement Performance (LTPP) program, FHWA, JUNE 2003, http://www.fhwa.dot.gov/publications/research/infrastructure/pavements/ltpp/reports/03031/03031.pdf
- ^ abAlligator Cracking, North Carolina Department of Transportation Pavement Management Unit, date accessed: November 21, 2010
- ^Alligator Cracking, Advanced Transportation Technology West Valley College, date accessed: November 9, 2010
- ^ abCrocodile Cracking, Local Government & Municipal Knowledge Base, accessed December 2, 2010
- ^Automated detection and classification of cracking in road pavements, Australian Road Research Board LLT, date accessed: December 4, 2010
As a professional that’s concerned with the pavement business, you’re probably well aware of the detrimental effects water intrusion can have on pavement life.
Untreated cracks in pavement enable water and incompressible materials to enter the cracks, damage the base and destroy the pavement. Cracks in pavement can expand and contract due to temperature, moisture and traffic. As cracks move and debris such as sand and dirt enter, additional stress is caused and micro-cracking below the surface further weakens and deteriorates the pavement.
Cracking In Asphalt Pavements
Crack sealing has long been a popular preventative measure to keep moisture out of the pavement, preventing potholes from forming and extending pavement life. Simply put, routed and sealed cracks are designed to perform better and to resist intrusion by water, impurities and incompressible materials. By adding crack routing to crack sealing efforts, you can help ensure those pavement preservation efforts will last up to twice as long.
Benefits to Pavement
In the same way that a dentist prepares a tooth before filling a cavity, crews must prepare cracks to receive sealants. The better the preparation, the better the chance that the sealant will have a longer service life and ultimately, extend the life of the pavement. Results from a recent Strategic Highway Research Program study showed that you can double sealant service life to perform more than 94 months if cracks are routed prior to sealing.
When sealant is applied to a crack that is not routed, the material is prone to being pushed up out of the crack when the pavement contracts in the warmer summer months. This leaves the sealant exposed to traffic to be worn away. This loss of sealant results in an inability to accommodate the crack expansion during the colder winter months. A routed crack has a reservoir of sealant that allows for seasonal expansion and contraction of the pavement movement, protecting the integrity of the sealant and extending its service life.
When sealant is applied into a routed reservoir, adhesion is improved and the sealant is better equipped to accommodate crack movement due to weather and traffic. Crack routing also allows the sealant level to remain below the surface of the pavement which protects the sealant from traffic and snowplow contact.
Benefits to Customers
As customers pay for services, they want to know they are going to get the most out of their investment. Crack routing can help achieve those long-term results customers are looking for.
Properly routed and sealed cracks remain sealed, reduce secondary crack development and reduce new crack development and spalling. The longer cracks stay sealed, the less your customer has to worry about moisture seeping in to their pavement and creating potholes.
Crack treatment is the lowest-cost pavement preservation treatment with the best benefit-to-cost ratio of AC pavement preservation treatments. Having a crack routing and sealing program gives customers the ability to right-size their budgets for early and routine treatments.
Crack routing and sealing achieves:
- Reductions in cracking distress
- Reduction in potholes and cracking from 75% to 1% of pavements within three years
- Increased pavement smoothness over a five-year period
- Reductions in raveling of pavement
Benefits to Contractors
The most expensive part of crack sealing is paying to have to seal that same crack again. Be sure your customers understand that.
Contractors who complete crack sealing work can tell their customers that properly sealed cracks can offer up to four years of protection. In comparison, cracks that are both routed and sealed offer up to seven years of pavement protection, thus almost doubling crack sealing efforts and giving the customers more bang for their crack sealing buck.
Pavement Crack Sealers
By offering crack routing to your customers, you’re providing them with properly prepared cracks that are 40% more likely to hold sealant and last almost twice as long. This also means you can also charge more money for your services.
Crack routing adds marginal cost to your business in comparison to other types of preservation treatments and significantly extends the service life of the pavement. With one additional piece of equipment – a router -- pavement maintenance contractors can add crack routing as a pavement preservation service that can bring in additional revenue and enhance the quality of their crack sealing efforts.
Bottom line: the longer a pavement performs, the more likely customers are to be happy with their investment in your services and repeat business with your company.