GB/T 13477.17-2017Test method for building sealants -- Part 17: Determination of elastic recovery (English PDF)

Foreword

GB/T 13477 Test method for building sealants is divided into 20 parts:

-- Part 1: Specifications for test substrates;

-- Part 2: Determination of density;

-- Part 3: Determination of extrudability of sealants using standardized apparatus;

-- Part 4: Determination of extrudability of one-component sealants;

-- Part 5: Determination for tack-free time;

-- Part 6: Determination of flow;

-- Part 7: Determination of low-temperature flexibility;

-- Part 8: Determination of tensile properties;

-- Part 9: Determination of adhesion/cohesion properties after immersion in water;

-- Part 10: Determination of tensile properties at maintained extension;

-- Part 11: Determination of tensile properties at maintained extension after

immersion in water;

-- Part 12: Determination of adhesion/cohesion properties at constant temperature;

-- Part 13: Determination of adhesion/cohesion properties at variable temperatures;

-- Part 14: Determination of resistance to prolonged exposure to water;

-- Part 15: Determination of adhesion/cohesion properties after exposure to heat

and artificial light through glass and to water;

-- Part 16: Determination of resistance to compression;

-- Part 17: Determination of elastic recovery;

-- Part 18: Determination of adhesion-in-peel;

-- Part 19: Determination of change in mass and volume;

-- Part 20: Determination of staining.

This part is Part 17 of GB/T 13477.

Test method for building sealants - Part 17: Determination

of elastic recovery

1 Scope

This part of GB/T 13477 specifies the method for determining the elastic recovery of

building sealing materials after maintaining a tensile state.

This part is suitable for determining the elastic recovery of building sealing materials.

2 Normative references

The following documents are essential to the application of this document. For the dated

referenced documents, only the versions with the indicated dates are applicable to this

document; for the undated referenced documents, only the latest version (including all

the amendments) is applicable to this document.

GB/T 13477.1 Test method for building sealants - Part 1: Specifications for test

substrates (GB/T 13477.1-2002, ISO 13640:1999, MOD)

GB/T 14682 Building sealing material vocabulary (GB/T 14682-2006, ISO

6927:1981, NEQ)

GB/T 22083-2008 Classification and requirements for building sealants (ISO

11600:2002, MOD)

3 Terms and definitions

The terms and definitions defined in GB/T 14682 apply to this document.

4 Principle

The specimen is stretched to the specified width, maintained in the tensile state for the

specified time, and then released. The elastic recovery (expressed as a percentage of

elongation) is calculated based on the change in width of the specimen before and after

stretching.

5 Standard test conditions

The standard test conditions of the laboratory are as follows: a temperature of (23±2) °C,

and the relative humidity of (50±5) %.

6 Test apparatus

7 Specimen preparation

Use degreasing gauze to remove floating dust from the surface of the cement mortar

board. Use acetone and other solvents to clean the aluminum plate and glass plate and

dry them.

9 Test steps

The test shall be carried out under standard test conditions. All measurements relevant

to the calculation of the elastic recovery are made by using vernier calipers (6.8),

measuring either the distance between the inner surfaces of the substrate that are in

contact with the sealing material, or the distance between the outer surfaces of the

substrate that are not in contact with the sealing material.

Remove the spacer block and measure the initial width Wi at both ends of each specimen.

Put the specimen into the tensile testing machine (6.6) and stretch the specimen at a

speed of (5.5±0.7) mm/min. The tensile elongation rate is 25%, 60%, or 100% of the

initial width (respectively stretched to 15 mm, 19.2 mm, or 24 mm), or a percentage

agreed upon by all parties, using We to represent the width after elongation. Use

appropriate positioning blocks to keep the specimen in a tensile state for 24 hours.

During the test, observe whether there is any damage to the specimen according to the

provisions of 7.3 in GB/T 22083-2008. If there is no damage, remove the positioning

block, place the specimen vertically on a smooth low-friction surface such as a glass

plate sprinkled with talcum powder in the long axis direction, let it stand for 1 hour, and

measure the width-after-recovery Wr at the same position at both ends of each specimen.

If there is any specimen failure, take a spare specimen and repeat the test in this part. If

there is still specimen failure among the three re-tested specimens, then report the test

results in this part as specimen failure.

Calculate the arithmetic mean values of Wi, We, and Wr measured at both ends of each

specimen, respectively.

10 Calculation of test results

The elastic recovery R of each specimen is calculated according to formula (1) and

expressed as a percentage:

where:

R -- elastic recovery, %;

Wi -- the initial width of the specimen, in millimeters (mm);

We -- the width of the specimen after stretching, in millimeters (mm);

Wr -- the width of the specimen after recovery, in millimeters (mm).

The arithmetic mean of the elastic recovery of the three specimens is calculated and

accurate to 1%.

11 Test report

The test report shall indicate the following content:

a) Name of the laboratory and the test date;

b) The number of this part;

c) Sample name, category (chemical type), color, and batch number;

d) Substrate category;

e) Primer used (if used), mixing ratio used (multi-component sample);

f) Specimen processing method (Method A or B);

g) Elongation (%);

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