When should random sampling be performed according to proper asphalt paving procedures?

Random sampling should be performed based on generated random numbers for cores to ensure that the samples taken for testing are unbiased and representative of the entire lot of pavement. This method enhances the reliability of test results, allowing for an accurate assessment of the asphalt quality and uniformity throughout the project. By using random numbers, inspectors can mitigate the effects of any potential biases in sampling location, which may arise if samples are taken systematically or subjectively.

Other options do not align with best practices for sampling. Performing random sampling before work starts may not accurately reflect the material being laid down during the actual paving process. Sampling after every vehicle passes could lead to excessive data collection without sufficient purpose, as it would not provide a comprehensive view of the overall asphalt quality. Sampling at scheduled intervals may overlook critical variations and does not incorporate the randomness necessary for a valid assessment of the entire lot’s integrity.