What are the different forms of asphalt distortion and its causes?

 Theer is many differents forms of  Distortions in an asphalt pavement are caused by instability of an asphalt mix or weakness of the base or subgrade layers. These distresses may include rutting, shoving, depressions, swelling and patch failures.Rutting. Rutting is a linear, surface depression in the wheelpath. Rutting is caused by deformation or consolidation of any of the pavement layers or subgrade. It can be caused by insufficient pavement thickness, lack of compaction, and weak asphalt mixtures.Shoving. Shoving is the formation of ripples across a pavement. This characteristic shape is why this type of distress is sometimes called wash-boarding. Shoving occurs at locations having severe horizontal stresses, such as intersections. It is typically caused by: excess asphalt; too much fine aggregate; rounded aggregate; too soft an asphalt; or a weak granular base.Depressions. Depressions, also call bird-baths, are localized low spots in the pavement surface. These flaws can be caused by settlement or other failure in the lower pavement layers or by poor construction techniques.Upheaval. Upheaval is a localized upward movement in a pavement due to swelling of the subgrade. Frost heave is an example of this type of distress.Patch Failures. When pavements are patched, some distress may begin to occur. The rate at which a patch deteriorates is influenced by compaction, materials selection, and the quality of the surrounding or underlying pavement.

Sorry i do not have the right answer

because it,s not my working field

I totally agree with the full answer of my brother Mr. fouad Ahmed Hussein.

So pleasure to be invited ^ _ ^. One of them is rutting that may happen either in asphalt layer or soil layers.1st case: due to poor quality of asphalt mix (AC content. Aggregate shape). Will not sustain the live load made by vehicles.2nd case: low relative compaction or poor grading that may lead to settlement to the soil layer.

 Thank you Mr. Jafar, in fact I do not have any addition to the information given by the answers of Mr. Fouad and Ahmed just I'd like to  add simple addition 

the maintenanceof Asphelt Deformation and Distresses  

- Maintenance work is not only costly but also lead to the other damages, for example, there is in the science of engineering Roads and Transport principle named Road maintenance socio-economic impact, that is mean the economic and the social impacts  of the work of road maintenance, that is how much will the state costs  through disruption of road users on the way, How will the economic movement disrupted due to the closure of roads or pathways converted

mechanical disortions

mix failures

foundation failings

frost

rain

DESIGN!