For an Aggregate Sub-base course with a volume of 5,000 cu.m at a 15cm depth, how many samples are required for CBR testing?

To determine the number of samples required for CBR (California Bearing Ratio) testing for an aggregate sub-base course, it's important to consider the standard practice for sampling in relation to the volume and depth of the material.

The CBR test is typically performed to evaluate the strength and load-bearing capacity of the sub-base. For a volume of 5,000 cubic meters at a depth of 15 cm, the sampling plan depends on guidelines that suggest a systematic approach to adequately represent the entire area being tested.

In general, for aggregate layers, a common practice is to take at least two representative samples to assess variability and ensure that the material meets the required specifications. Having two samples allows for comparison between different locations within the project area, helping to account for any inconsistencies in material properties that may arise.

If only one sample were taken, it might not reflect the overall quality of the aggregate in the entire volume if there are fluctuations in the material’s characteristics. With three or more samples, while potentially providing more data, it may exceed what is necessary for this specific volume. Thus, two samples strike a balance between sufficient representation and efficient testing for this aggregate sub-base.

Therefore, the requirement for two samples aligns with the practices recommended for this circumstance, ensuring