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GB/T 14685-2022 English PDF (GBT14685-2022)

GB/T 14685-2022 English PDF (GBT14685-2022)

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GB/T 14685-2022: Pebble and crushed stone for construction

This document stipulates the classification and categories, general requirements, technical requirements, test methods, inspection rules, marking, storage, transportation of pebbles and crushed stone used for construction. This document applies to pebbles and crushed stone, which are used in cement concrete and its products in construction projects (except hydraulic buildings).
GB/T 14685-2022
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 91.100.15
CCS Q 13
Replacing GB/T 14685-2011
Pebble and crushed stone for construction
ISSUED ON: APRIL 15, 2022
IMPLEMENTED ON: NOVEMBER 01, 2022
Issued by: State Administration for Market Regulation.
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 6
2 Normative references ... 6
3 Terms and definitions ... 6
4 Classifications and categories ... 8
5 General requirements ... 8
6 Technical requirements ... 8
7 Test methods ... 11
8 Inspection rules ... 48
9 Marking, storage, transportation ... 49
Pebble and crushed stone for construction
1 Scope
This document stipulates the classification and categories, general requirements, technical requirements, test methods, inspection rules, marking, storage, transportation of pebbles and crushed stone used for construction.
This document applies to pebbles and crushed stone, which are used in cement concrete and its products in construction projects (except hydraulic buildings). 2 Normative references
The contents of the following documents constitute essential provisions of this document through normative references in the text. Among them, for dated reference documents, only the version corresponding to the date applies to this document; for undated reference documents, the latest version (including all amendments) applies to this document.
GB 175 Common Portland cement
GB/T 2419 Test method for fluidity of cement mortar
GB/T 6003.1 Test sieves - Technical requirements and testing - Part 1: Test sieves of metal wire cloth
GB/T 6003.2 Test sieves - Technical requirements and testing - Part 2: Test sieves of perforated metal plate
GB 6566 Limits of radionuclides in building materials
GB 8076-2008 Concrete admixtures
GB/T 14684-2022 Sand for construction
GB/T 17671 Test method of cement mortar strength (ISO method)
SL/T 352-2020 Test code for hydraulic concrete
3 Terms and definitions
The following terms and definitions apply to this document.
7.3.2.2 Weigh the specimen according to the provisions of Table 11. Pour the specimen onto a set of sieves (with sieve bottom), which are assembled from top to bottom, according to the hole size. Then sieve.
7.3.2.3 Place the sieve set on the sieve shaker, to shake the sieve for 10 minutes. Remove the sieve set and sieve by hand one by one, according to the size of the sieve holes, until the throughput per minute is less than 0.1% of the total specimen mass. The particles that have passed are merged into the next sieve, which are sieved together with the specimen in the next sieve. In this order, make it pass all sieves. When the particle size of the remaining particles is greater than 19.0 mm, it is allowed to use fingers to stir the particles during the screening process.
7.3.2.4 Weigh out the screening residue of each size sieve.
7.3.3 Result calculation and evaluation
7.3.3.1 Calculate the sub-calculated screening residue percentage: The ratio of the screening residue of each size sieve to the total mass of the specimen, which shall be accurate to 0.1%.
7.3.3.2 Calculate the cumulative screening residue percentage: The sum of the sub- calculated screening residue percentages of this sieve and above sieves, which shall be accurate to 1%. After screening, if the difference -- between the sum of the screening residue of each sieve and the screening residue at the bottom of the sieve and the mass of the specimen before screening -- exceeds 1%, the test shall be performed again. 7.3.3.3 Evaluate the particle gradation of the specimen, based on the cumulative screening residue percentage of each size sieve.
7.4 Clay content in pebble and clay content and fine content in crushed stone 7.4.1 Instruments and equipment
Instruments and equipment shall meet the following requirements:
a) Oven: Temperature controlled at (105 ?? 5) ??C;
b) Balance: The graduation value is not greater than 0.1% of the minimum specimen mass;
c) Test sieve: A square hole sieve, which has hole diameter of 75 ??m and 1.18 mm; d) Container: When washing the specimen, keep the specimen from splashing; e) Shallow plate: Porcelain or metal.
7.4.2 Test procedures
ma1 - The mass of the dried specimen before the test, in grams (g);
ma2 - The mass of the dried specimen after the test, in grams (g).
7.4.3.2 The clay content in pebbles and clay content and fine content in crushed stone shall be the arithmetic mean of the two test results, accurate to 0.1%. When the difference between the two results exceeds 0.2%, it shall take sample again for the testing.
7.5 Clay lumps and friable particles content
7.5.1 Instruments and equipment
Instruments and equipment shall meet the following requirements:
a) Oven: Temperature controlled at (105 ?? 5) ??C;
b) Balance: The graduation value is not greater than 0.1% of the minimum specimen mass;
c) Test sieve: Square hole sieve, which has hole diameter of 2.36 mm and 4.75 mm; d) Container: When washing the specimen, keep the specimen from splashing; e) Shallow plate: Porcelain or metal.
7.5.2 Test procedures
The single particle size of 5 mm ~ 10 mm shall be processed according to the method specified in 7.6 of GB/T 14684-2022. The following steps shall be followed for other particle sizes:
a) Take samples according to the provisions of 7.1. Reduce the specimen to no less than 2 times the mass specified in Table 12. Place it in an oven, to dry it to constant weight at (105 ?? 5) ??C. After cooling to room temperature, screen out the particles smaller than 4.75 mm. Divide it into two equal parts for later use;
b) Weigh a portion of the specimen (mb1). Pour the specimen into the elutriation container. Inject clean water, so that the water level is higher than the upper surface of the specimen. Stir thoroughly. Soak (24 ?? 0.5) hours. Then crush the mud block in water. Then place the specimen on a 2.36 mm sieve. Wash with water, until the water in the container is clear by visual inspection;
c) Take out all the retained specimen from the sieve. Put them into a shallow plate. Dry them in an oven at (105 ?? 5) ??C to a constant weight. After cooling to room temperature, weigh their mass (mb2).
7.5.3 Result calculation and evaluation
a) Reagents: Sodium hydroxide, tannic acid, ethanol, distilled water;
b) Sodium hydroxide solution: Dissolve 3 g of sodium hydroxide in 97 mL distilled water;
c) Standard solution: Dissolve 2 g of tannic acid in 98 mL of ethanol solution (10 mL of absolute ethanol plus 90 mL of distilled water), to obtain a tannic acid solution. Then take 25 mL of this solution. Inject it into 975 mL of sodium hydroxide solution. Add a stopper. Shake vigorously. Let stand for 24 h, to obtain the standard solution.
7.8.2 Instruments and equipment
Instruments and equipment shall meet the following requirements:
a) Balance: The measuring range is not less than 2 kg, the graduation value is not more than 2 g. The measuring range is not less than 100 g, the graduation value is not more than 0.1 g;
b) Graduated cylinder: 100 mL, the graduation value is not more than 1 mL; 1000 mL, the graduation value is not greater than 5 mL;
c) Test sieve: A square hole sieve, which has a hole diameter of 19.0 mm; d) Beaker, glass rod, pipette, etc.
7.8.3 Test procedures
7.8.3.1 Take samples according to the provisions of 7.1. Screen out particles larger than 19.0 mm. Then reduce the particles to about 1.0 kg. Air-dry them for later use. 7.8.3.2 Put the dry specimen into the 1000 mL graduated cylinder to the 600 mL mark. Then inject the sodium hydroxide solution to the 800 mL mark. Stir vigorously. Let it stand for 24 hours.
7.8.3.3 Compare the colors of the upper solution of the specimen and the standard solution. The sizes of the measuring cylinders containing the standard solution and the specimen shall be consistent.
7.8.4 Result evaluation
7.8.4.1 When the color of the upper solution of the specimen is lighter than the color of the standard solution, it means that the organic matter content of the specimen is qualified.
7.8.4.2 When the colors of the two solutions are close, the specimen shall be poured into the beaker together with the upper solution. Place it in a water bath at 60 ??C ~ 70 ??C, to heat for 2 h ~ 3 h. Then compare it with the standard solution. When it is lighter than the standard solution, the organic matter content is considered qualified. 7.8.4.3 When the upper solution of the specimen is darker than the standard solution, it shall be prepared into concrete for further testing. The preparation method is as follows: take a portion of specimen; use 3% sodium hydroxide solution to wash away the organic matter; use clean water to rinse it, until the color of the upper solution is lighter than the standard solution. Prepare concrete using the same raw materials and mix proportion as another unwashed specimen. Cure it under the same conditions. Measure the 28 d compressive strength. When the strength of concrete made from unwashed specimen is not less than 95% of the strength of concrete, which is from washed specimen, the organic matter content is deemed to be qualified.
7.9 Sulfide and sulfate content (based on SO3 mass)
7.9.1 Reagents and materials
Reagents and materials shall comply with the following requirements:
a) Barium chloride solution: Dissolve 5 g of barium chloride in 50 mL distilled water; b) Dilute hydrochloric acid: Mix concentrated hydrochloric acid with the same volume of distilled water;
c) Silver nitrate solution: Dissolve 1 g of silver nitrate in 100 mL distilled water; then add 5 mL ~ 10 mL of nitric acid; store it in a brown bottle;
d) Filter paper: Medium speed quantification, slow speed quantification. 7.9.2 Instruments and equipment
Instruments and equipment shall meet the following requirements:
a) Oven: Temperature controlled at (105 ?? 5) ??C;
b) Balance: The measuring range is not less than 1 kg, the graduation value is not greater than 1g; the measuring range is not less than 100 g, the graduation value is not greater than 0.0001 g;
c) High temperature furnace: The temperature is controlled at (800 ?? 25) ??C; d) Test sieve: A square hole sieve which has a hole diameter of 75 ??m;
e) Beaker: 300 mL;
f) Graduated cylinder: 20 mL and 100 mL, which has a graduation value not greater than 1 mL;
g) Grinding bowl or crusher;
me1 - The specimen mass, in grams (g).
7.9.4.2 The arithmetic mean of the two test results shall be taken as the sulfide and sulfate content, accurate to 0.1%. If the difference between the two test results is greater than 0.2%, the test shall be repeated.
7.10 Soundness
7.10.1 Reagents and materials
Reagents and materials shall comply with the following requirements:
a) Barium chloride solution: Dissolve 5 g of barium chloride in 50 mL distilled water; b) Sodium sulfate solution: In a certain mass of distilled water (the amount of water depends on the specimen volume and the size of the container). Heat to 30 ??C ~ 50 ??C. Add 350 g of anhydrous sodium sulfate (Na2SO4) per 1000 mL of water. Use a glass rod to stir whilst adding, to dissolve and saturate it. Then cool to 20 ??C ~ 25 ??C. Let stand at this temperature for 48 hours, which is the test solution. 7.10.2 Instruments and equipment
Instruments and equipment shall comply with the following requirements. a) Oven: The temperature is controlled at (105 ?? 5) ??C.
b) Balance: The measuring range is not less than 5 kg, the graduation value is not more than 1 g.
c) Tripod mesh basket: It is made of high-strength, high-temperature-resistant, corrosion-resistant materials. The outer diameter of the mesh basket is 100 mm, the height is 150 mm, the hole diameter of the mesh is 2 mm ~ 3 mm. When inspecting particles of 37.5 mm ~ 90 mm, it shall use a mesh basket, which has an outer diameter and height of 150 mm.
d) Container: Non-iron, with a volume of not less than 50 L.
e) Glass rod, etc.
7.10.3 Test procedures
7.10.3.1 Take samples according to the provisions of 7.1. Reduce the specimen to the mass specified in Table 19. Use water to rinse it clean. Dry it in an oven at (105 ?? 5) ??C to a constant weight. Wait until it cools to room temperature. Screen out particles smaller than 4.75 mm. Then screen them into five particle sizes of 4.75 mm ~ 9.50 mm, 9.50 mm ~ 19.0 mm, 19.0 mm ~ 37.5 mm, 37.5 mm ~ 63.0 mm, 63.0 mm ~ 90.0 mm according to the provisions of 7.3. Weigh the mass (mf0i) of specimen of each particle size sequentially.
mj1 - The mass of the saturated surface dry specimen, in grams (g);
mj2 - The mass of the specimen after drying, in grams (g).
7.15.3.2 The water absorption shall be the arithmetic mean of the two test results, accurate to 0.1%.
7.16 Radioactivity
It is carried out, according to the provisions of GB 6566.
7.17 Alkali-aggregate reaction
7.17.1 Determination of rock types and alkali-active aggregate category Identify the rock type and alkali-active aggregate category, according to the method specified in 3.36 of SL/T 352-2020. When the aggregate contains alkali-active components, further inspection will be carried out according to the category. 7.17.2 Alkali-silicic acid reaction (fast method)
7.17.2.1 Reagents and materials shall meet the following requirements:
a) NaOH solution: Prepare by dissolving (40 ?? 1) g of NaOH (chemically pure) in 1 L water (distilled water or deionized water), which has a concentration of 1 mol/L; b) Cement: Grade 42.5 Portland cement in compliance with GB 175 or benchmark cement in compliance with Appendix A of GB 8076-2008.
7.17.2.2 Instruments and equipment shall comply with the following requirements: a) Oven: Temperature controlled at (105 ?? 5) ??C;
b) Balance: The measuring range is not less than 1000 g; the graduation value is not more than 0.1 g;
c) Test sieves: Square hole sieves which have a hole diameter of 4.75 mm, 2.36 mm, 1.18 mm, 0.60 mm, 0.30 mm, 0.15 mm;
d) Comparator: It consists of a dial indicator and a bracket; the measuring range of the dial indicator is 10 mm, the graduation value is not greater than 0.01 mm; e) Cement mortar mixer: It meets the requirements of GB/T 17671;
f) High temperature constant temperature curing box or water bath: The temperature is maintained at (80 ?? 2) ??C;
g) Curing cylinder: It is made of materials that can withstand long-term alkali corrosion and high temperature (80 ??C). It shall not leak. It has a sealing cover e) After the mixing is completed, immediately put the mortar into the test mold, which is equipped with the expansion probe, in two batches. Pound each layer 40 times. Note that the surrounding area of the expansion probe shall be compacted solidly. After pouring, use a trowel to scrape off the excess mortar. Smoothen it. Number it. Mark direction of measurement.
7.17.2.5 Curing and length measurement shall comply with the following requirements. a) After the specimen is formed, immediately put the mold into the standard curing chamber. After curing for (24 ?? 4) hours, remove the mold. When the strength of the specimen is low, removal of mold can be extended to after 48 hours. Immediately measure the initial length of the specimen. The specimen to be tested shall be covered with a damp cloth, to prevent moisture from evaporating. b) After measuring the initial length, immerse the specimen in the water in the curing cylinder. The same set of specimens shall be installed in one curing cylinder; the water temperature shall be kept within the range of (80 ?? 2) ??C. Cover it. Place it in high temperature constant temperature curing box or water bath, for curing for (24 ?? 2) h.
c) Take out the curing cylinder from the high temperature constant temperature curing box or water bath. Open the sealing cover. Take out the specimen. Use a towel to wipe dry the surface. Immediately measure the reference length (L01) of the specimen. It shall finish reading, within (15 ?? 5) s after removing the specimen. Cover the specimen with a wet towel. After all the specimens have been measured for reference length, immerse the specimen in the 1 mol/L NaOH solution in the curing cylinder. Keep the solution temperature within the range of (80 ?? 2) ??C. Cover and place in a high temperature constant temperature curing box or water bath.
d) The length measurement age is calculated from the date when the reference length is measured. Take it out for length measurement (Lt1), on the 3rd, 7th, 14th day. Each length measurement time is arranged at approximately the same time every day. The length measurement method is the same as that for measuring the reference length. After each length measurement, the specimen shall be placed in the original curing cylinder, covered and returned to a high temperature constant temperature curing box or water bath of (80 ?? 2) ??C, to continue curing, until reaching to the next test age. If length measurement needs to be continued after 14 days, length measurement can be arranged once every 7 days.
7.17.2.6 Result calculation and evaluation shall comply with the following provisions. a) The expansion rate of the specimen shall be calculated according to formula (19), accurate to 0.001%.
d) Comparator: It consists of dial indicator and bracket. The measuring range of the dial indicator is 10 mm; the graduation value is not greater than 0.01 mm; e) Cement mortar mixer: It meets the requirements of GB/T 17671;
f) Constant temperature curing box or curing chamber: Temperature (40 ?? 2) ??C, relative humidity above 95%;
g) Curing cylinder: It is made of materials that can withstand alkali corrosion for a long time. It shall not leak. It has a sealing cover and can hold 3 specimens. There is a specimen holder inside the cylinder, to allow the test specimens to stand upright in the cylinder. There is no contact between the specimens and between the specimen and the cylinder wall;
h) Test mold: The specification is 25 mm ?? 25 mm ?? 280 mm. There are small holes in the middle of both ends of the test mold, that can be used to bury the expansion probe. The expansion probe is made of stainless metal, which has a diameter of 5 mm ~ 7 mm and a length of 25 mm;
i) Breakers, dryers, calipers or micrometers, trowels, tampers, shallow plates, brushes, etc.
7.17.3.3 Environmental conditions shall comply with the following requirements: a) The temperature of materials, molding chamber, curing chamber shall be maintained at (20 ?? 2) ??C;
b) The relative humidity of the forming chamber and length measuring chamber shall not be less than 50%;
c) The temperature of the constant temperature curing box or curing chamber shall be maintained at (40 ?? 2) ??C; the relative humidity shall be above 95%. 7.17.3.4 The preparation of specimens shall comply with the following requirements. a) Take samples according to the provisions of 7.1. Reduce them to about 5.0 kg. After crushing, sieve the specimen into five particle sizes of 0.15 mm ~ 0.30 mm, 0.30 mm ~ 0.60 mm, 0.60 mm ~ 1.18 mm, 1.18 mm ~ 2.36 mm, 2.36 mm ~ 4.75 mm. After each particle size is rinsed with water on the corresponding sieve, it is dried in an oven at (105 ?? 5) ??C to constant weight; stored in a dryer for later use. b) Use Portland cement or benchmark cement. Use NaOH to adjust the alkali content [calculated as Na2O, that is, m (K2O) ?? 0.658 + m (Na2O)] to be no less than 1.2%. c) The mass ratio of cement to aggregate is 1:2.25. A set of three specimens requires a tota...

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