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2- CBR ratio for a sample submerged and compressed to the maximum density
should be not less than 80. 3-
Would rather be a regular gradient-General should also not exceed the pass- through the No. 200 sieve 0.5 from passing No. 40 sieve.
The thickness of base course is 25 cm
d. Prime coat
It is a MC asphalt mixture by the kerosene is sprayed over the base layer before placing the asphalt.
e. Tack Coat
Consists of adding gasoline to the bituminous is sprayed on the first layer of asphalt for preparation to serve second layer, for paste layers.
f. Surface Course
the surface course of a flexible structure consists of a mixture of mineral aggregates and bituminous materials placed as the upper course and usually
constructed on a base course .In addition to its major function as a structural portion of the pavement, it must also be designed to resist the abrasive forces of
traffic, to reduce the amount of surface water penetrating the pavement, to provide a skid resistance surface, and to provide a smooth and uniform riding surface.
Thickness of This top structural layer of material is 11 cm subdivided into 6 cm
layer the first layer is called Binder Course and 5 cm and a second layer called
wearing Course.
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4.3 Inspection procedures
The evaluation of pavement condition included consideration of specific problems that existed in the pavement. This requires a determination of the types and
causes of distress, as well as the extent of pavement deterioration. Pavement inspection is conducted on inspection units. An inspection unit is a small segment of a
pavement section or management unit selected of convenient size which is then inspected in detail. The distress found in the inspection unit is used to calculate the
PCI for the inspection unit inspected. The PCI of the inspected inspection units in the section are then used to represent the condition of the entire section.
When a small area of pavement is found to be much worse than the majority of the pavement, it can be inspected and identified as a special inspection unit. This
was used to identify areas of localized deterioration such as an area damaged by utility cuts, crossing of construction traffic or other localized problems. A weighted
average was used to calculate the PCI when special inspection units are inspected. The inspector inspects the sample unit by walking the inspection unit or
standing on the curbshoulder, and recording the type, severity and amount of each distress present in the inspection unit. The type, severity and amount must correspond
to those defined in this distress identification manual. The quantities and severities should normally be estimated using measuring techniques as accurate as pacing when
the inspector can walk the inspection unit and by visual estimation when he stands on the curb or shoulder ASTM, 1999.
The inspection method is designed to allow the calculation of a composite rating index called the pavement condition index PCI. The steps for determining the
PCI of an inspection unit are shown in analysis of data inChapter III.The PCI scale is shown in figure 2.20 in Chapter II .The distress types ,severity levels descriptions
must be carefully followed since they were used in the development of the deduct curves. Failure to do so could invalidate the PCI calculated.
THE study road lie in north east part of Libya in Koms city .Type of road is secondary road; it is link by length 20 km between city center and Mslata village. This project
was a field study of a road length of 1000 m two directions, and was divided into 10 parts a length of 100 m of each part.
