[Don]

There was another article earlier last week which mentioned the epoxy process, if I recall correctly:

1. On site, the resin and hardner material are forced/inserted into the drilled hole in the concrete at the same time.
2. The bolt is inserted and then tightned. The threads on the bolt, as it is tightned , mix the two substances together forming the epoxy .

Other Boston Globe comments:

Many more flaws detected;
Loose ceiling fixtures number in hundreds


More than 240 loose ceiling bolt fixtures are scattered throughout the Interstate 90 connector tunnel, said Turnpike Authority officials, who announced yesterday that the tunnel could remain closed for weeks as engineers determine whether to repair or replace the tunnel's drop ceiling.

The problems with the connector tunnel went unnoticed until after Monday night, when the car Del Valle was riding in to Logan International Airport was crushed by two ceiling panel sections that had come loose.

Each panel was secured to the top of the I-90 connector tunnel by bolt fixtures that include the bolts, epoxy, and metal plates. Tieback rods hang from the plate and suspend steel beams supporting the concrete panels.

The bolts were inserted into holes drilled in the ceiling, then glued into place using high-strength epoxy. When properly installed, the metal plates are tightly flush against the tunnel's ceiling. The suspect bolts are in places where gaps between the plates and ceiling are at least one-sixteenth of an inch.

Yesterday, work crews finished removing the remaining 10 ceiling panel sections, which engineers call modules, from the eastbound I-90 connector tunnel. Each panel was cataloged by law enforcement officials who are working alongside Turnpike Authority crews to build a potential criminal case. The work crews also plan to remove eight panel sections from above the westbound lanes and 10 from above the high-occupancy vehicle lanes.

Turnpike Authority inspectors conducting visual examinations of the ceiling found 50 problem bolt fixtures in the eastbound section, 10 fewer than the number the Turnpike Authority had estimated on Wednesday. The westbound section had 68, the HOV lane 45, and two exit ramps had a total of 79.

Big Dig chief engineer Michael Swanson explained yesterday that the 242 problematic bolts were visually identified by small gaps between the steel plate and the ceiling. He said officials did not know whether any of these had endangered motorists.



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