What is the physical meaning of 85 drainage that defines the

What is the physical meaning of “85% drainage” that defines the degree of drainage in a pavement system by the AASHTO 1993 Design Guide?

Solution

There are two approaches for characterizing the time to drain–one is the AASHTO percent drained (50 percent) and the other is 85 percent saturation. AASHTO percent drained (50 percent) assesses the drainability of \'pavement subsurface system\', on the basis of the time within which 50 percent of infiltrated water is drained.

physical meaning of 85% drainage :

To evaluate the drainage quality of a pavement based on the time with which the amount of infiltrated water is drained to the extent that the degree of saturation for the \'base layer\' is below 85 percent.

So,time to drain infiltrated water so that the degree of saturation in the base layer is less than 85 percent