Which test measures the California Bearing Ratio (CBR) of soil?

The test that measures the California Bearing Ratio (CBR) of soil is indeed the CBR test. This test is specifically designed to evaluate the strength and load-bearing capacity of soil, particularly for use in road and pavement design. The CBR value is determined by comparing the pressure required to penetrate the soil with a standard cylindrical plunger to the pressure required to penetrate a standard crushed stone material. This provides a clear indication of the soil's suitability for supporting heavy loads, which is critical in highway construction and maintenance.

The CBR test is commonly used in the field to assess subgrade materials and to help engineers design more effective pavement structures. It provides valuable data that helps in determining the thickness of pavement layers needed to support anticipated traffic loads. The test is straightforward and provides reliable results that can directly influence design decisions, making it an essential part of evaluating soil for highway projects.