What does a CBR Value tell us?

The California Bearing Ratio (CBR) is a measure of the strength of the subgrade of a road or other paved area, and of the materials used in its construction.

What is R-Value in road construction?

The R-Value test measures the ability of the tested material to resist lateral spreading due to an applied vertical load. This test is designed to mimic vertical loads seen in roads, such as tire loads. The R-value test is measured on a scale from 0-100, 0 being water and 100 being steel. How is the test performed?

Why perform CBR test?

The CBR is a penetration test used for determining the subgrade strength value of pavements and roads. These results of tests are used with help of curves to determine the pavement thickness and various subgrade layers.

What is R-Value in geotechnical?

The R-Value test 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.

What is soaked and Unsoaked CBR?

A soaked sample is created by soaking the sample for 4 days. Both soaked and unsoaked CBR tests are used in the assessment of granular materials used in bases, subbases, and subgrades. The evaluation of strength behavior is considered to be most criti- cal on the wet side of the optimum moisture content (OMC).

How do you carry out a CBR test?

The CBR test is performed by measuring the pressure required to penetrate a soil sample with a plunger of standard area. The measured pressure is then divided by the pressure required to achieve an equal penetration on a standard crushed rock material. The harder the surface, the higher the CBR value.

What is CBR of soil?

CBR is the ratio expressed in percentage of force per unit area required to penetrate a soil mass with a standard circular plunger of 50 mm diameter at the rate of 1.25 mm/min to that required for corresponding penetration in a standard material. The ratio is usually determined for penetration of 2.5 and 5 mm .

What is the R-value of compacted soil?

about R 0.125 to R 0.25 per inch
A short answer to the R-Value of Dirt – about R 0.125 to R 0.25 per inch. Some sources we researched assert that “one inch of ‘insulation’ is equal to about two feet or more of soil.

How is CBR test performed?

How is a CBR Test performed? The CBR test is performed by measuring the pressure required to penetrate a soil sample with a plunger of standard area. The measured pressure is then divided by the pressure required to achieve an equal penetration on a standard crushed rock material.

Is pea gravel a good insulator?

If you use sand, or even pea gravel, you will likely not trap enough air to properly insulate the space. If your gravel is too big, it will be hard to install and may trap too much air, also reducing the insulation value.