In construction materials testing, what does CBR stand for?

In construction materials testing, CBR stands for California Bearing Ratio. This test is widely used to evaluate the strength and load-bearing capacity of soil subgrades and aggregate bases in both flexible pavement design and road construction. The CBR test involves measuring the pressure required to penetrate a soil sample with a standard cylindrical plunger, which provides a ratio comparing the soil's strength to a standard crushed stone.

The California Bearing Ratio is crucial in determining material suitability for supporting pavement and guiding decisions on the design and thickness of pavement layers. Its derived values help engineers predict performance under load and define necessary construction specifications.

The other options do not reflect established terminologies in materials testing. "Concrete Bearing Ratio," "Composite Bearing Ratio," and "Cubic Bearing Ratio" are not recognized terms in construction or soil mechanics, as they do not correspond to established tests or methodologies used to assess the bearing capacity of materials in the context of construction engineering.