Nondestructive Testing of Concrete T-Walls, Atchafalaya Basin Protection Levees, New Orleans District

摘要

Nondestructive testing measurements were made on two concrete inverted T-walls constructed in the east and west protection levees of the Atchafalaya Basin. These T-walls are to accommodate a 36-in. crude oil pipeline that will cross the basin. Ultrasonic velocity measurements were made through the upright portion of the walls where visible seams of apparent inadequate compaction and exposed reinforcing steel caused concern for the structural integrity of the walls. Measurements were also made to determine if there were any defects in critical areas such as near the intersections of the vertical wall and the base slab. In each wall there is a section of concrete which houses the casing collar where the pipeline passes through the walls. The wall surfaces in these areas were alleged to have been patched and smoothed with a neat cement grout to cover numerous surface irregularities. Velocities obtained in these particular areas of both walls confirm the presence of inferior quality material. The measurements made in other areas of the east wall produced only one velocity that is indicative of concrete of questionable quality. Four of the 32 velocities obtained from the other areas of the west wall indicated inferior quality concrete. Attempts to make determinations concerning the continuity of the foundation piles using the pulse-echo technique were not successful. (Author)