Pavement failure occurs when an asphalt surface no longer holds its original shape and develops material stress which causes issues. Pavement failure issues include cracking, potholes, depressions, rutting, shoving, upheavals, and ravelling.
What Causes Pavement Failure?
Pavement failure is caused by a number of variables including, water intrusion, stress from heavy vehicles, expansion and contraction from seasonal temperature changes, and sun exposure. It is important to keep up with proper maintenance like crack and asphalt sealing to prevent cracks from spreading or forming.
Asphalt cracking by far makes up for the majority of pavement failure issues because of its tendency to spread and the wide variety of elements that can cause cracking. It is fairly normal for an asphalt surface to crack over time due to the settling of soil and the exposure to the outdoor elements, however, there are some less usual and common cracking issues that can form from improper mix design for pavement construction.
Alligator cracking forms when the subgrade and asphalt base begins to compress from bearing heavy vehicles. Alligator cracking is commonly found at intersections where vehicles are stopped for a continuous amount of time. Initial cracks will form and spread through water intrusion and further asphalt base compression.
Edge cracking forms along the edge of a road and is typically caused by water damage, insufficient base material, and heavy road usage.
Block cracking is formed by seasonal temperature differences that cause the asphalt to expand and contract. Block cracking will form if an asphalt surface has too rigid of a mix design that does not give the surface room for seasonal density changes.
Joint cracking forms along asphalt overlay projects where a flexible concrete base is paved over. Over time the concrete sub-base will expand and contract causing cracks to form along the joints of the concrete.
Transverse cracks run across an asphalt roadway and are caused by settling or shifting base material, improper paver operation, and extreme temperature shifts.
Linear cracking runs parallel with the roadway and are most commonly caused by pavement fatigue but can also be an issue related to weaker points in a parking lot or roadway pavement joints.
Potholes are formed through prolonged water intrusion from existing cracks in the surface. If alligator cracks and other asphalt stress cracks are not treated, water will begin to erode the surface all the way down to the sub base. This will cause large holes to form in the asphalt which will spread and cause damage to vehicles. Once a pothole is formed a patch can be applied to the surface, but because the sub base has been destroyed the area will continue to become compacted.
A depression in an asphalt surface is formed by uneven sub-bases or compactions over time. Depressions have a lower elevation than the asphalt surface which will cause the area to hold water for longer. Water buildup can cause further issues like raveling or potholes.
Rutting is channeled depressions in an asphalt surface that form over time from exceeded weight limits and improper base construction. Over time heavy vehicles will begin to compact the asphalt along a roadway creating tire ruts. If rutting forms in an asphalt surface the base must be repaired or restructured to account for heavier vehicle traffic.
Ravelling is caused by the continued intrusion of water and the degradation of an asphalt top coat. Once the top layer of asphalt bitumen wears down water and sunlight will continue to damage the asphalt surface causing the bond between asphalt bitumen and aggregate rock to break. Once ravelling occurs an asphalt surface will lose it impervious properties and will let water enter the surface. When water begins to intrude into an asphalt surface it will cause further cracks and pavement failure to occur.
Austin Asphalt Repair
If your road, parking lot, or asphalt surface is experiencing pavement failure, it is best to fix the issue before it worsens or spreads. At Lone Star Paving we offer a free on-site consultation where we can identify and come up with an action plan for asphalt pavement issues. If you suspect your asphalt surface is experiencing pavement failure, contact Lone Star Paving Today.