What type of adhesive does this standard apply to?

It applies to adhesives for structural laminated wood products for use in exterior or weather-exposed conditions.

What is the main test for weather resistance?

The primary tests are the 'resistance to delamination' tests (cyclic test in Clause 4.3 and boiling test in Clause 4.4), which assess the bond's durability against moisture.

What is the minimum shear strength required for Group 1 timber?

The minimum block shear strength is 110 kgf/cm² in dry conditions and 80 kgf/cm² after a wet cyclic test, as per Table 1.

What is the maximum allowable delamination?

Maximum delamination should not exceed 10% in the cyclic test (Clause 4.3) or 5% in the boiling test (Clause 4.4).

IS 9188

: 1979

Performance requirements for adhesive for structural laminated wood products for use under exterior exposure conditions

CurrentSpecializedSpecificationMaterials Science · Wood and Other Lignocellulosic Products

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This standard specifies the performance requirements and testing methods for adhesives used in manufacturing structural laminated wood products intended for exterior use. It covers bond quality, working properties, and resistance to environmental factors like moisture and temperature cycling through delamination and shear tests.

Performance requirements for adhesive for structural laminated wood products for use under exterior exposure conditions

Quick Reference Values

Min dry block shear strength (Group 1 timber)110 kgf/cm²

Min wet block shear strength (Group 1 timber)80 kgf/cm²

Max allowable delamination in cyclic test10%

Max allowable delamination in boiling test5%

Min failing load for plywood shear test (dry)120 kgf

Practical Notes

This standard is critical for ensuring the long-term durability of glued laminated timber (glulam) in exposed conditions, preventing bond failure due to moisture ingress.

Adhesives meeting this standard are typically high-performance thermosetting resins like phenol-resorcinol formaldehyde (PRF).

The tests prescribed, especially the cyclic delamination and boiling tests, are accelerated weathering tests to simulate harsh exterior conditions.