ISO 19993:2020

ISO 19993:2020 pdf free.Timber structures – Glued laminated timber一Face and edge joint
cleavage test.
4 Principle
A specimen consisting of a full cross-section of laminated timber is cleaved apart in the plane of the
bond lines and wood failure is assessed after wet or dry conditioning.
Cleavage is achieved by cutting a saw kerf that straddles the bond line then using a chisel, usually a
bricklayer’s bolster, that is placed in the saw kerf and is struck with a hammer to produce stresses
perpendicular to the grain, in other words, to induce cleavage. If there is sufficient wood failure it
means that the adhesive bond is stronger than that of the wood and that there is no loss of strength
perpendicular to the grain at the interface between laminations.
5 Apparatus
5.1 Chisel, with a wedge angle and thickness such that the tip of the blade does not touch the bottom
of the saw cut of the test specimen before cleavage failure begins to occur; see Figure 2.
The width of the chisel shall exceed that of the specimen.
NOTE A bricklayer’s bolster is a suitable implement.
5.2 Hammer or mallet, with a minimum mass of 1 kg.
5.3 Wood cutting equipment, such as a panel saw, band saw or circular saw.
5.4 Autoclave or similar vessel, designed to withstand safely a pressure of at least 500 kPa, equipped
with a vacuum pump capable of drawing a vacuum of at least 65 kPa (500 mm of mercury) in the vessel and a pump or other device to provide a pressure of at least 500 kPa.
6 Preparation of test pieces
A member to be tested shall be manufactured to a slightly longer length than specified to allow for a
representative specimen or specimens to be removed at the end of the member. The specimen[s) shall be removed from the off-cut portion at the end of the member after trimming to length. Each specimen shall be marked to identify the member from which it is cut.
The specimens shall include the full cross-section of the laminated timber to be tested, perpendicular
to the grain of the wood and 50 mm long measured along the grain. Each bond line of the specimen
shall be cut uniformly the full width of the specimen to a depth of 10 mm from one cross-cut face. For convenience, the specimen may be divided into smaller parts, provided the cuts are perpendicular to or well away from the bond lines and that all parts are tested (see Figure 1).
7.2 Conditioning for wet cleavage
The conditioning shall be undertaken as follows:
a] The test specimens shall be placed in the autoclave and fully immersed in water between 10 °C
and 27 °C. The specimens shall be restrained so that they remain fully immersed throughout the
conditioning period. The specimens shall be supported in such a manner that all end grain surfaces
are exposed to the water.
b] A vacuum of at least 65 kPa shall be drawn and held for 1,5 h, then the vacuum shall be released and pressure of (500土30] kPa applied for 1,5 h. The vacuum-pressure cycle shall be repeated once more. For higher density species, longer pressure and vacuum cycles may be required to achieve total water penetration. .ISO 19993 pdf download.

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