1 Scope
This part of GB/T 328 specifies test methods for the determination of the tensile properties of plastic and rubber sheets for roof waterproofing.
Method A (ISO 1421) is applicable to all materials; where Method A is not applicable and there is no break on the material, Method B (GB/T 528) may be used to determine the tensile property.
2 Normative References
The following standards contain provisions which, through reference in this text, constitute provisions of GB/T 328. For dated reference, subsequent amendments to (excluding correction to), or revisions of, any of these publications do not apply. However, all parties coming to an agreement according to this standard are encouraged to study whether the latest edition of these documents is applicable. For undated references, the latest edition of the normative document is applicable to these specifications.
GB/T 328.1 "Test methods for building sheets for waterproofing—Part 1:Bitumen plastic and rubber sheets for waterproofing rules for sampling"
GB/T 328.5 "Test methods for building sheets for waterproofing—Part 5:Plastic and rubber sheets for waterproofing-thickness and mass per unit area"
GB/T 528 "Rubber，vulcanized or thermoplastic - Determination of tensile stress-strain properties"( GB/T 528-1998 eqv ISO 37:1994)
JJG 139-1999 "Verification Regulation of Universal Tension and Compression Testing Machine"
ISO 1421 "Rubber-or plastics-coated fabrics—Determination of tensile strength and elongation at break"
3 Terms and Definitions
For the purposes of GB/T 328, the following terms and definitions apply.
3.1 top surface
Upper side of the sheet, as used in situ. This is usually the inside of the roll.
3.2 maximum tensile force
Largest value of tensile force recorded during testing
3.3 elongation at maximum tensile force
elongation of the test specimen at the maximum tensile force.
3.4 elongation at break
elongation of the test specimen at rupture.
4 Principle
A test specimen is stretched at a constant speed until it ruptures. The force and elongation is continuously recorded throughout the test, and preferably with a permanent record of the maximum tensile force.
5 Apparatus
Tensile testing machine equipped with a continuous recording of force and corresponding elongation and capable of maintaining a uniform speed of grip separation as specified below.
The tensile testing machine shall have a sufficient loading capacity of at least 2000 N and a grip separation speed of (100 ± 10 and 500 ± 50) mm/min. The width of grips shall not be less than 50 mm.
The tensile testing machine shall be equipped with grips of a type which maintain or increase the clamping pressure as a function of the increase of the tensile force applied to the test specimen. The test specimen shall be held so that it does not slip in the grips more than 1 mm for products up to and including 3 mm thick, and 2 mm for thicker products. A mark or tape on the test specimen where it enters the grips will help reveal any slip.
The method of gripping shall not induce premature rupture close to the grips.
If the slippage from the grips exceeds the stated limits the actual elongation of the test specimen shall be measured with an extensometer.
The force measuring system shall meet at least Class 2 of JJG 139-1999 (i.e. ± 2 %).
