How to Measure Possible causes Description

32 aggregate due to oil or fuel spillage and surface seal loss are also in cluded under raveling.

b. Severity levels

- Low level of intensity L: Aggregate or binder of the pavement or surface seal has started to wear away .In some area, the surface is starting to pit .In the case of oil spillage, the oil stain can be seen, but the surface is hard and cannot be penetrated with a coin. - Medium level of intensity M: Aggregate and or binder has worn away or the original pavement is showing through the surface seal in a few places. The surface texture is moderately rough and pitted .In the case of oil spillage. - Higher level of intensity H: Aggregate and or binder have been considerably worn away or much of the surface seal has been lost. The surface texture is very rough and severely pitted. The edge of the pavement has broken up to the extent that pieces are missing with in3m to 6mof the edge .In the case of oil spillage, the asphalt binder has lost its binding effect and the aggregate has become loose.

c. How to Measure

Weathering and raveling are measured in square meter of surface area.

d. Possible causes

i. Horizontal shear stress as a result of traffic. ii. Oxidation or aging of asphalt materials and the separation of gravel Association, and the lack of materials, excess heat to the mixture, and the lack of asphalt content and insufficient compaction and the use of gravels weak in the mix asphalt. iii. The presence of water that has permeated into the class by spaces, which leads to the hydrostatics pressure at the impact of the movement. 33 iv. Emission of hydrocarbons for a long period of car engines works hydrocarbon solvent for asphalt materials.

2.3.2.7 Polished Aggregate Polished gravel

a. Description

Aggregate polishing is caused by repeated traffic applications. Polished aggregate is present when close examination of a pavement reveals that the portion of aggregate extending above the asphalt is either very small or there are no rough or angular aggregate particles to provide good skid resistance. Existence of this type of distress is also indicated when the number on a skid resistance rating test is low or has dropped significantly from previous ratings.

b. Severity levels