AASHTO M 176M/M 176-20

AASHTO M 176M/M 176-20 covers porous nonreinforced concrete pipe for use in underdrains.

This specification agrees with ASTM C 654M-05a and C 654-05a except that the absorption test is limited to the 5-h boil method, the manufacturer is not afforded the option to supply inch-pound sized pipe when the order is placed in SI units, and the use of fibers in Section 6.5 is at the owner's option.