Quantcast Chemical Damage

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form of a fracture through the member cross section or as crushing of the wood
fiber.
In glued-laminated members, deterioration may be in the form of adhesive
bond failure. This delamination may be from the action of moisture on non-
waterproof glue or from an inadequate bond during fabrication. The impor-
tance in terms of physical damage depends on the size and location of the
delamination relative to critical loading points. If glulam timbers become wet
and dry out quickly, severe checking can develop. This checking can be mistaken
for delamination because it often occurs near a glueline. Regardless, it is the
extent of the checking or delamination that needs to be determined.
1.2.3-C CHEMICAL DAMAGE. If wood comes into contact with cer-
tain chemicals such as strong acids or alkalis, some of its constituents may be
decomposed and it may disintegrate. Wood that has been damaged by contact
with a chemical may be discolored or assume a fuzzy, wooly appearance, owing
to the individual fibers having become separated by dissolution of those substances
which bind them together in wood.
The type of chemical damage most frequently encountered in wooden struc-
tures is that associated with the corrosion of metal fasteners. Wood subjected
to constant or frequent wetting assumes a blue-black color adjacent to iron nails,
screws, bolts, or other fasteners and, in time, softens to varying degrees.
1-14





 


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