The CBR laboratory test: What is it, and what is your procedure?

CBR Test

The test CBR (California Bearing Ratio: Test California Bearing Ratio) measures the resistance to shear of soil and to evaluate the quality of soil for subgrade, subbase, and base pavements. It is carried out under controlled humidity and density conditions. For the CBR Test this is an important deal.

Extended description

We differentiate different types of CBR according to soil quality, namely:

  • CBR undisturbed floors.
  • CBR remodeled floors.
  • CBR gravel and sandy soils.
  • CBR cohesive floors little or nothing plastic.
  • CBR plastic cohesive floors.

This procedure can be carried out in compacted soil.

This procedure measures the load necessary to penetrate a piston of determined dimensions at a previously fixed speed in a compacted sample of soil after it has been immersed in water for four days at the most unfavorable saturation and after having measured its swelling.

The sample is submerged to be able to foresee the hypothetical situation of moisture accumulation in the soil after construction. Therefore, after having compacted the soil and having submerged it, it is penetrated with a piston which is connected to a small “plotter” that generates a graph where the load is represented with respect to the depth to which the piston has penetrated inside. of the sample.

CBR Test

The graph obtained is usually a curve with the initial straight section and the final