preface
GB/T9966 "Test Methods for Natural Stone" is divided into 18 parts:
Part 1: Compressive strength tests after drying, water saturation, freeze-thaw cycles;
Part 2: Flexural strength tests after drying, water saturation, freeze-thaw cycles;
Part 3: Water absorption, bulk density, true density, true porosity test;
Part 4: Abrasion resistance test;
Part 5: Hardness test;
Part 6: Acid resistance test;
Part 7: Hanging strength test of stone pendant combination unit;
Part 8: Test method for detecting the structural strength of stone hanging system with uniform static differential pressure;
Part 9: Determination of the dynamic modulus of elasticity by measuring the fundamental frequency of resonance;
Part 10: Determination of seismic performance of pendant combination units;
Part 11: Determination of Accelerated Aging Intensity of Cooling and Heat-Stimulation;
Part 12: Determination of the static modulus of elasticity;
Part 13: Determination of capillary water absorption coefficient;
Part 14: Determination of fracture resistance;
Part 15: Determination of Aging Strength of Salt Spray Resistance;
Part 16: Determination of the coefficient of linear thermal expansion;
Part 17: Determination of the crystallization strength of salts;
Part 18: Petrographic analysis.
This part is part 17 of GB/T9966.
This part is drafted in accordance with the rules given by GB/T1.1-2009.
This part is proposed by the China Building Materials Federation.
This part is under the supervision of the National Stone Standardization Technical Committee (SAC/TC460).
The drafting units of this part: Sinoma Intraocular Lens Research Institute Co., Ltd., Beijing Sinoma Intraocular Lens Research Institute Co., Ltd., Nan'an Quality Metrology and Testing Institute, Global Stone (Dongguan) Co., Ltd.
The main drafters of this part: Zhou Junxing, Chen Junying, Lu Liangyong, Zhang Yu, Huang Xukun.
1 Scope
This part of GB/T9966 stipulates the principle, instruments and equipment, sample preparation, test steps, test results and test report for determining the crystalline strength of natural stone salts.
This part is applicable to the determination of the crystalline strength of natural stone salts.
2 Normative references
The following documents are essential for the application of this document. Where a reference is dated, only the dated version applies to this document. For undated references, the most recent version of the document (including all change orders) applies to this document.
GB/T17670 natural stone unified number.
3 Principle
After drying to constant weight, the specimen is soaked in sodium sulfate solution, removed and dried and then cooled to room temperature, and the percentage change in mass is measured after 15 cycles.
4 Instruments and equipment
4.1 Blast drying oven: the temperature can be controlled at (105±5) °C.
4.2 Balance: The measuring range should not be less than 200 g, and the measurement accuracy should not be less than 0.01 g.
4.3 Laboratory or water bath: can keep the temperature of the sample and solution at (20±0.5)°C.
4.4 14% sodium sulfate decahydrate solution: that is, 86g of deionized water is mixed with 14g of Na₂SO₄· 10H₂O, and the solution density is 1.055kg/m³ at 20 °C.
4.5 Dryer: A sealed container that should hold at least one set of specimens with a built-in desiccant.
5 Specimen preparation
5.1 Number of specimens
At least 6 representative specimens should be prepared in the same material.
5.2 Specimen specifications
The surface of the cube with a side length of (40±1) mm is a wet cut surface of a diamond circular saw blade, and the irregular surface should be polished and smooth.
5.3 Cleaning
All loose materials on the surface of the specimen should be rinsed with clean water.
5.4 Drying
The specimen is dried in a blast drying oven at (105±5) °C for 24h to constant weight, and then the specimen is placed in a dryer to cool to room temperature. Weigh the mass (mA) to the nearest 0.01g. Each specimen is permanently marked, and then the mass (mA) is weighed to the nearest 0.01 g.
6 Test Procedure
6.1 14% sodium sulfate decahydrate solution should be used in the test, and the density of the solution should be checked before use, and the solution should be changed once in a cycle.
6.2 Each dry sample is placed in a 250mL container, the bottom is lined with glass rods to support the sample, sodium sulfate solution is added to make the distance between the upper surface of the sample and the solution surface (8±2) mm, and the lid of the container is covered to reduce evaporation. If the dry specimens are placed in a container at the same time, the minimum distance between the specimens should be 10 mm, and the distance between the specimens and the edge of the container should be at least 20 mm. The specimen was soaked in a solution of (20±0.5) °C for 2h.
6.3 Before putting the sample in, put a dish of water in the cold oven, and heat the oven for (30±5) min to maintain a relatively high humidity. For a 125 L oven, up to 48 specimens can be dried using (300±25) mL of water. The soaked specimen was dried in an oven, and the temperature in the oven was raised to (105±5) °C and kept for (20±2) h.
6.4 After drying the sample in the oven for (20±2) h, cool it to room temperature for (2.0±0.5) h, and then soak it in a new sodium sulfate solution for the next cycle. Repeat the above process 15 times unless the specimen is broken. After 15 cycles, the specimen was removed from the oven and placed in water at (23±5) °C for (24±1) h. Finally, the specimen is thoroughly washed with running water and weighed according to the dry specimen described in 5.4 (mí).
6.5 If there is a fault such as fracture or breakage of the specimen in the test, record the status and the number of cycles completed, and keep the records of the initial and final state images of the specimen. If the test process is interrupted, the specimen should be stored in an oven at (105±5) °C.
7 Test results
The relative mass change for each specimen is calculated by Eq. (1) and expressed as a percentage of the mass change (mass loss or increase) to the initial dry mass:
………………… (1)
where:
△m – change in relative mass (decrease or increase in mass) before and after the test, expressed in %;
m; - the mass of the labeled dried specimen after 15 cycles in grams (g);
MAI – the mass of the labelled dry specimen in grams (g) before the first cycle;
mA – the mass of the dried specimen in grams (g).
The arithmetic mean of each group of samples was used as the test results. If the final specimen fails to be weighed due to breakage, the result is expressed in terms of the number of cycles that caused the failure.
8 Test report
The trial report should contain at least the following information:
a) The commercial name of the stone according to GB/T17670;
b) The number of samples, specifications and sizes, and surface treatment conditions (according to the needs of the test);
c) the date of sample submission, preparation and measurement;
d) The name and address of the testing laboratory, or if the place where the test is conducted is not the testing laboratory, the place where the test was conducted;
e) The standard number of the test (GB/T9966.17-2021);
f) the percentage change in the mass of each specimen;
g) the arithmetic mean of the test results;
h) Test deviations (e.g. specimen size and surface treatment, etc.).
bibliography
[1] EN 12370:1999Natural stone test methods-Determination of resistance to salt crystalli-zation
The material comes from the Internet.
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