What are the representative value and qualified value of pavement thickness?

[AshleyLee]

In the design of expressway pavement thickness, the allowable deviation for the representative value is 5%. According to the "Highway Engineering Quality Inspection and Evaluation Standard" (JTGF80/1-2017), the representative value of the measured pavement thickness should not be less than 95% of the design thickness (with a guarantee coefficient of 95%, and when n>100, ta=1.6449). The qualification rate is then calculated based on the single-point qualified value. If the representative value fails to meet the standard, it is directly rated as unqualified. As a key project, the qualification rate of pavement thickness should not be lower than 95% (for contracts signed before May 2018, the rate is 90%).