What is the CBR of base course?
The base course is normally the highest-quality structural material used in a flexible-pavement structure, having CBR values near the CBR standard material (crushed limestone). Base courses are always cohesionless materials and are normally processed to obtain the proper gradation.
What is the aggregate type for base course?
Aggregates: Aggregates for bases shall be crushed stone, crushed slag, crushed gravel or natural gravel that conforms to the quality requirements of AASHTO M147, except that the requirements for the ratio for the minus No. 200 sieve fraction to the minus No.
What is sub base and base course?
Subbase Course. The layer between the base course and subgrade. It functions primarily as structural support but it can also minimize the intrusion of fines from the subgrade into the pavement structure and improve drainage.
What is P 209 crushed aggregate?
209-2.1 AGGREGATE. Aggregates shall consist of clean, sound, durable particles of crushed stone, crushed gravel, or crushed slag and shall be free from coatings of clay, silt, vegetable matter, and other objectionable materials and shall contain no clay balls.
What should be the CBR value for crushed rock material?
The CBR is expressed as a percentage of the actual load causing the penetrations of 2.5 mm or 5.0 mm to the standard loads on crushed stone. A load penetration curve is drawn. The load values on standard crushed stones are 1,370 kgf (13.44 kN) and 2,055 kgf (20.15 kN) at 2.5 mm and 5.0 mm penetrations respectively.
What is a typical CBR value of a high quality well graded crushed stone?
The California Bearing Ratio (CBR) test is a simple strength test that compares the bearing capacity of a material with that of a well-graded crushed stone (thus, a high quality crushed stone material should have a CBR @ 100%).
What are the two types of base course?
Two types of base courses will be con- sidered in this paper, the fine a^regate type and the coarse aggregate type. The fine aggregate type material contains less than 35 percent of coarse aggregate (material re- tained on a No. 10 sieve) and the coarse aggregate type contains from 35 to 70 percent coarse aggregate.
What is base course used for?
Under rigid pavements, the base course is used to: (1) provide uniform and stable support, (2) minimize damaging effects of frost action, (3) provide drainage, (4) prevent pumping of fine-grained soils at joints, (5) prevent volume change of the subgrade, (5) increase structural capacity of the pavement, and (6) …
What is p209?
209-2.1 AGGREGATE. Aggregates shall consist of clean, sound, durable particles of crushed stone, or crushed gravel, or crushed slag and shall be free from coatings of clay, silt, vegetable matter, and other objectionable materials and shall contain no clay balls.
What is p209 stone?
Coarse L Gravel. 2″minus material with no fines in it.