Criteria for the bonding quality of plywood shall be as
follows:
Plywood Type Special
For Type Special, the
plywood product shall meet the requirement of either (1), (2) or (3) (limited
to those consist of softwood veneers only) of all of the followings:
- As
the results of Continuous Boiling Test specified in 3(2) of the Appendix,
the average wood failure ratio and shear strength shall be not less than
the values provided in Table (1). In this case, for layers with its
fiber direction mostly parallel to that of the adjacent veneers
(hereinafter, referred to as ‘parallel layer’), the length of non‐delaminated portion on the same
bonding layer of the specimen shall be not less than 2/3 of the length of
each side.
- As
the results of Cyclic Steaming Test specified in 3(2) of the Appendix, the
average wood failure ratio and shear strength shall be not less than the
values provided in Table (1). In this case, for the parallel layers,
the length of non‐delaminated portion on the same bonding layer of the
specimen shall be not less than 2/3 of the length of each side.
- As
the results of Vacuum Pressure Test as specified in 3(2) of the Appendix,
the specimens shall meet the following conditions from a. to c. In
this case, for the parallel layers, the length of non-delaminated portion
on the same bonding layer of the specimen shall be not less than 2/3 of
the length of each side.
a.
The average wood failure ratio of all test specimens shall be not
less than 80%.
b. The number of test
specimens with the wood failure ratio of 60% or greater shall be not less than
90%.
c.
The number of test specimens with the wood failure ratio of 30% or
greater shall be not less than 95%.
Plywood Type 1
For Type I, the plywood
product shall meet the requirement of either (1), (2) or (3) (limited to
Concrete forming plywood consists of softwood veneers only) of all of the followings. However, for Surface
processed concrete forming plywood, Natural wood decorative plywood, Specially
processed decorative plywood and Special core plywood (referring to the plywood with
other than ‘veneer core’, hereinafter the same), as the results
of Type I Immersion Delamination Test specified in 3(3) of the Appendix,
the length of non-delaminated portion on the same bonding layer of the
specimen shall be not less than 50mm at each side.
- As
the results of Cyclic Boiling Test specified in 3(2) of the Appendix, the
average wood failure ratio and shear strength shall be not less
than the values provided in Table (1). In this case, for the
parallel layers, the length of non-delaminated portion on the
same bonding layer of the specimen shall be not less than 2/3 of the
length of each side.
- As
the results of Steaming Treatment Test specified in 3(2) of the Appendix,
the average wood failure ratio and shear strength shall be not
less than the values provided in Table (1). In this case, for
the parallel layers, the length of non-delaminated portion on
the same bonding layer of the specimen shall be not less than 2/3 of
the length of each side.
- As
the results of Vacuum Pressure Test as specified in 3(2) of the Appendix,
the average wood failure ratio and shear strength shall be not
less than the values provided in Table (1). In this case, for
the parallel layers, the length of non-delaminated portion on the same
bonding layer of the specimen shall be not less than 2/3 of the length of
each side.
Plywood Type II
For Type II of Plywood for
General Use (except for the special core plywood), as the results of Hot and
Cold Water Immersion Test specified in 3(2) of the Appendix, the average wood
failure ratio and shear strength shall be not less than the values provided in
Table (1). In this case, for the
parallel layers, the length of non‐delaminated portion on the same bonding
layer of the specimen shall be not less than 2/3 of the length of each side.
For Type II of Natural wood
decorative plywood, Specially processed decorative plywood and Special core
plywood, as the results of Type II Immersion Delamination Test specified in 3(3)
of the Appendix, the length of non‐delaminated portion on the same bonding
layer of the specimen shall be not less than 50mm at each side.
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