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The CBR test is a penetration test in which a standard piston, with a diameter of 50 mm (1.969 in), is used to penetrate the soil at a standard rate of 1.25 mm/minute. Although the force increases with the depth of penetration, in most cases, it does not increase as quickly as it does for the standard crushed rock, so the ratio decreases.
It is a pointed cone attached to a spring-loaded handle by extension spindles. The device is pushed into the ground and a scale reads off the estimated CBR value. It is a quick and simple means of estimating the CBR of the top 0.5 metres of subgrade but is less accurate than the more involved standard CBR test.
In this report the CBR-method (California Bearing Ratio) is primarily referred to. The so-called CBR-value represents the ratio of the percentage of the loads required to press a punch of certain dimensions first into a well compacted sample of soil and then into a standard sample of compacted gravels, to a depth of 0.1 inch.
Ultralow strength: characterized by K = 20 MN/m^3 and representing all K values below 25 MN/m^3 for rigid pavements, and by CBR = 3 and representing all CBR values below 4 for flexible pavements D: Maximum allowable tire pressure: Unlimited: no pressure limit W: High: limited to 1.75 MPa X: Medium: limited to 1.25 MPa Y: Low: limited to 0.50 MPa Z
The R-Value test [1] measures the response of a compacted sample of soil or aggregate to a vertically applied pressure under specific conditions. This test is used by Caltrans for pavement design, replacing the California bearing ratio test. Many other agencies have adopted the California pavement design method, and specify R-Value testing for ...
The test reports loss of mass to abrasion and impact, expressed as a percentage of initial sample mass. [7] Maximum acceptable loss for the base course of the road is 45%; the more demanding surface course must be 35% or less. [1] The test was developed by the city engineers of Los Angeles in the 1920s. [8]
The test cartridge must be inserted into the chamber in such a way that the hole in the test cartridge case lines up with a gas port hole that channels the gas pressure from the cartridge case to the face of the sensor. The measurement accuracy of the pressure measurements with 21st century high-pressure sensors is expected to be ≤ 2%. [7]
CBR Innovation Network (or Canberra Innovation Network), a government innovation; Central Bank of Russia; Center for Bio-Ethical Reform, an anti-abortion non-profit organization; Centre for Blood Research, at the University of British Columbia; Central Board of Revenue, the Pakistan department for revenue collection