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GB/T 12960-2019 English PDF (GBT12960-2019)

GB/T 12960-2019 English PDF (GBT12960-2019)

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GB/T 12960-2019: Quantitative determination of constituents of cement

This Standard specifies the methods of quantitative determination of constituents of Portland cement, ordinary Portland cement, slag Portland cement, pozzolanic Portland cement, fly-ash Portland cement and composite Portland cement. This Standard is applicable to cement containing one or more materials among granulated blast-furnace slag, pozzolanic mixed material, fly ash, limestone, sandstone, kiln dust, gypsum and Portland cement clinker.
GB/T 12960-2019
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 91.100.10
Q 11
Replacing GB/T 12960-2007
Quantitative Determination of Constituents of Cement
ISSUED ON: OCTOBER 18, 2019
IMPLEMENTED ON: SEPTEMBER 1, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of the PEOPLE Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative References ... 5
3 Basic Requirements for Test ... 5
4 Reagents and Materials ... 6
5 Instruments and Equipment ... 8
6 Preparation of Specimens ... 11
7 Determination of Cement Constituents - Method 1 ... 11
8 Determination of Cement Constituents - Method 2 ... 18
9 Precision ... 22
Quantitative Determination of Constituents of Cement
1 Scope
This Standard specifies the methods of quantitative determination of constituents of Portland cement, ordinary Portland cement, slag Portland cement, pozzolanic Portland cement, fly-ash Portland cement and composite Portland cement.
This Standard is applicable to cement containing one or more materials among granulated blast-furnace slag, pozzolanic mixed material, fly ash, limestone, sandstone, kiln dust, gypsum and Portland cement clinker.
2 Normative References
The following documents are indispensable to the application of this document. In terms of references with a specified date, only versions with a specified date are applicable to this document. In terms of references without a specified date, the latest version (including all the modifications) is applicable to this document. GB/T 176 Method for Chemical Analysis of Cement
GB/T 5484 Methods for Chemical Analysis of Gypsum
GB/T 6682 Water for Analytical Laboratory Use - Specification and Test Methods GB/T 8170 Rules of Rounding off for Numerical Values and Expression and Judgement of Limiting Values
GB/T 12573 Sampling Method for Cement
GB/T 35151 Determination of Total Organic Carbon in Limestone
3 Basic Requirements for Test
3.1 Test Number and Requirements
The number of tests for each determination is specified as two. Use the average value of two test results to represent the determination result.
The methods of the determination of constituents of cement are divided into Method 1 and Method 2. If multiple determination methods are listed for the same constituent, Method 1 shall prevail when there is a dispute.
3.2 Laboratory Temperature
It is required that laboratory temperature shall be between 16 ??C ~ 30 ??C. 3.3 Constant Mass
After the first drying or burning, cooling and weighing, through the method of continuously drying or burning the vessel or specimen for 15 min each time, and then, cooling and weighing it, determine the constant mass. When the difference of two consecutive weighings is less than 0.0005 g, it reaches a constant mass. 3.4 Processing of Results
3.4.1 After selective dissolution, the content of insoluble slag, the content of carbon dioxide and the content of sulfur trioxide shall be counted by mass fraction, and the numerical value shall be expressed in a percentage (%) to two decimal places; the content of sulfide (calculated by S) shall be counted by mass fraction, and the numerical value shall be expressed in a percentage (%) to three decimal places. 3.4.2 The determination result of the content of various constituents in cement shall be counted by mass fraction, and the numerical value shall be expressed in a percentage (%) to one decimal place.
3.4.3 The rounding-off of numerical values shall be carried out in accordance with GB/T 8170.
4 Reagents and Materials
Unless it is otherwise specified, all reagents shall be not lower than analytically pure. The used water shall be not lower than the requirements for Grade-3 water specified in GB/T 6682. Carbon dioxide-free water refers to water that is freshly boiled and cooled to room temperature.
4.1 Nitric acid (HNO3): density: 1.39 g/cm3 ~ 1.41 g/cm3; mass fraction: 65% ~ 68%. NOTE: the density of commercially available concentrated liquid reagents listed in this Standard refers to the density (???) at 20 ??C, the same below.
4.2 Sulfuric acid (H2SO4): density: 1.84 g/cm3; mass fraction: 95% ~ 98%. 4.3 Phosphoric acid (H3PO4): density: 1.68 g/cm3; mass fraction ??? 85%.
4.4 Triethanolamine [N(CH2CH2OH)3]: density: 1.12 g/cm3; mass fraction: 99%. 4.5 Ethanol (C2H5OH): mass fraction: 95%.
4.6 Nitric acid (1 + 5).
NOTE 1: use volume ratio to indicate the degree of reagent dilution, the same below. Nitric standard buffer solution at different temperatures are shown in Table 1. 4.12 Copper sulfate (CuSO4 ??? 5H2O) saturated solution.
4.13 Hydrogen sulfide absorbent: place the weighed dry pumice with a particle size of 1 mm ~ 2.5 mm in a flat pan, then, use a certain volume of copper sulfate saturated solution to soak it (see 4.12). The mass of the copper sulfate solution is about half the mass of the pumice. Place the mixture in a drying oven (5.2) at 150 ??C ?? 5 ??C; under constant stirring with a glass rod, evaporate the mixture to dryness, then, dry it for above 5 h. After the solid mixture is cooled, store it in a sealed bottle. 4.14 Soda lime: particle size: 2 mm ~ 5 mm; medical or chemically pure; sealed and stored.
4.15 Alkali asbestos: particle size: 1 mm ~ 2 mm (10 mesh ~ 20 mesh); chemically pure; sealed and stored.
4.16 Anhydrous magnesium perchlorate [Mg (ClO4)2]: made into a particle size of 0.6 mm ~ 2 mm; stored in a sealed bottle.
5 Instruments and Equipment
5.1 Balance: division value is not less than 0.0001 g.
5.2 Drying oven: controlled temperature 105 ??C ?? 5 ??C, 150 ??C ?? 5 ??C.
5.3 Acidity meter: pH value measurement value 0 ~ 14, accurate to 0.02. 5.4 Glass sand core funnel: with a diameter of 35 mm ~ 60 mm; model G4 (average pore size: 3 ??m ~ 4 ??m).
Glass sand core crucible of the same specification may also be used.
5.5 Suction filter flask: 1,000 mL.
5.6 Air pump: pumping speed 0.25 L/s.
5.7 Cement constituent determination device: able to maintain a constant temperature of 20 ??C ?? 2 ??C, as it is shown in Figure 1.
2---U-shaped tube: internally hold alkali asbestos (4.15);
3---buffer bottle;
4---reaction flask: 100 mL;
5---separating funnel;
6---electric furnace;
7---spherical condenser tube;
8---gas scrubber: internally hold sulfuric acid (4.2);
9---U-shaped tube: internally hold hydrogen sulfide absorbent (4.13);
10---U-shaped tube: internally hold anhydrous magnesium perchlorate (4.16); 11, 12---U-shaped tube: internally hold alkali asbestos (4.15) and anhydrous magnesium perchlorate (4.16);
13---U-shaped tube: internally hold soda lime (4.14) or alkali asbestos (4.15). Figure 2 -- Schematic Diagram of Carbon Dioxide Determination Device with Alkali Asbestos Absorption Weighing Method
The gas entering the device firstly passes through the absorption tower 1 containing soda lime (4.14) or alkali asbestos (4.15) and the U-shaped tube 2 containing alkali asbestos (4.15); the carbon dioxide in the gas is removed. The upper part of the reaction flask 4 is connected with the spherical condenser tube 7.
After the gas passes through the spherical condenser tube 7, it enters the gas scrubber 8 containing sulfuric acid (4.2), then, passes through the U-shaped tube 9 containing hydrogen sulfide absorbent (4.13) and the U-shaped tube 10 containing anhydrous magnesium perchlorate (4.16); the hydrogen sulfide and moisture in the gas are removed. Then, the gas passes through two weighable U-shaped tubes 11 and 12, which respectively contain 3/4 alkali asbestos (4.15) and 1/4 anhydrous magnesium perchlorate (4.16). In terms of the gas flow direction, alkali asbestos (4.15) shall be installed before anhydrous magnesium perchlorate (4.16). The U-shaped tubes 11 and 12 are followed by an additional U-shaped tube 13, which internally holds soda lime (4.14) or alkali asbestos (4.15), so as to prevent carbon dioxide and moisture in the air from entering the U-shaped tube 12.
5.9 U-shaped tube. The sizes of the weighable U-shaped tubes 11 and 12 in Figure 2 shall comply with the following stipulations:
---Inner distance between two straight tubes: 25 mm ~ 30 mm
limestone constituent.
Sandstone is counted in the pozzolanic mixed material or fly-ash constituent. 7.2 Test Procedures
7.2.1 Determination of insoluble slag content after selective dissolution with nitric acid solution
Weigh-take 0.5000 g ?? 0.0200 g of specimen (m3), accurate to 0.0001 g. Place it in a 200 mL dry beaker; add 80 mL of water; put in a stirring bar. Place the beaker on the cement constituent determination device (see 5.7) shown in Figure 1; control the temperature at 20 ??C ?? 2 ??C; stir it for 5 min, so that the specimen is completely dispersed.
Then, add 50 mL of nitric acid (1 + 5) that has been maintained at a constant temperature in 20 ??C ?? 2 ??C water; continue to stir for 30 min, then, remove it. Immediately use a glass sand core funnel that has been dried at 105 ??C ?? 5 ??C to a constant mass, or, a glass sand core funnel with a layer of quick filter paper (see 5.4) for suction and filtration.
The constant-mass glass sand core funnel is pre-processed, that is, firstly, use a brush and water to wash it (if necessary, use hot diluted hydrochloric acid and water to filter and wash it, then, add a layer of wet quick filter paper), then, in a 105 ??C ?? 5 ??C drying oven, dry it to a constant mass; in the desiccator (see 5.11), cool it to room temperature and weigh it (m1).
Use tweezers to take out the stirring bar, then, use water to wash it. Transfer all the insoluble slag to the glass sand core funnel; use water to wash the insoluble slag for 6 ~ 7 times, then, use ethanol (see 4.5) to wash it twice (the total amount of the washing liquid is about 80 mL).
During filtering, wait for the previous washing liquid to be completely leaked, then, proceed to the next washing. The filtration shall be prompt. If the filtration time exceeds 20 min (including washing), the test shall be re-conducted.
Put the glass sand core funnel (with filter paper) and the insoluble slag into 105 ??C ?? 5 ??C drying oven; dry for above 40 min. Take it out, then, place it in the desiccator (see 5.11) to cool it to room temperature; weigh it. Repeat the drying in this mode, until it reaches a constant mass (m2).
7.2.2 Determination of insoluble slag content after selective dissolution with EDTA solution
Respectively use phosphate pH standard buffer solution (see 4.10) and borate pH standard buffer solution (see 4.11) to calibrate the acidity meter (see 5.3). When taking the U-shaped tubes, be careful, and avoid affecting the mass or causing any damage, or getting injured. When performing the operations, wear protective gloves.
Weigh-take about 1 g of specimen (m10), accurate to 0.0001 g; place it in a dry 100 mL reaction flask. Connect the reaction flask to the device (see 5.8) shown in Figure 2; connect the already-weighed U-shaped tubes 11 and 12 to the device (see 5.8) shown in Figure 2. Actuate the air pump, control the gas flow rate to be about 50 mL/min ~ 100 mL/min (3 ~ 5 bubbles per second). Add 20 mL of phosphoric acid to the separating funnel 5; carefully unscrew the piston of the separating funnel, so as to drop the phosphoric acid into the reaction flask 4. In addition, leave a little amount of phosphoric acid in the funnel as a liquid seal, then, close the piston. Turn on the small electric furnace under the reaction flask; adjust the voltage so that the electric furnace heating wire manifests dark red. Slowly heat at a low temperature to bring the liquid in the reaction flask to boiling; heat it to slightly boiling for 5 min, then, turn off the electric furnace; continue to ventilate for 25 min.
DO NOT vigorously heat it, so as to prevent the liquid in the reaction bottle from flowing back.
Turn off the air pump; close the grinding plugs of the U-shaped tubes 10, 11, 12 and 13. Remove the U-shaped tubes 11 and 12; place them in the desiccator (see 5.11); maintain them at a constant temperature for 10 min, then, respectively weigh them. Use the added masses (m7 and m8) of each U-shaped tube to calculate the carbon dioxide content in the cement.
If the mass change of the second U-shaped tube 12 is less than 0.0005 g, it may be ignored in the calculation. In fact, all the carbon dioxide shall be absorbed by the first U-shaped tube 11.
Meanwhile, perform a blank test. During the calculation, the blank test value (m9) is deducted from the determination result.
7.2.4 Determination of sulfate sulfur trioxide content in specimen
The determination of sulfate sulfur trioxide content (w) in cement shall be conducted in accordance with GB/T 176.
7.3 Processing of Test Result
7.3.1 Calculation of insoluble slag content after selective dissolution with nitric acid solution
The insoluble slag content (a) in cement after selective dissolution with nitric acid solution shall be calculated in accordance with Formula (1):
The carbon dioxide absorbs infrared energy of a certain wavelength, and the absorbed energy is directly proportional to the content of carbon; through the energy value received by the detector, determine the content of carbon dioxide. The automatic photoelectric titration method uses phosphoric acid to decompose the specimen; the carbon dioxide released by the decomposition of carbonate is absorbed by ethanol - ethanolamine solution. Use thymolphthalein as the indicator; use potassium hydroxide - ethanol standard titration solution for the automatic tracking of titration. The determination of gypsum constituent adopts the X-ray diffraction analysis method. Adopt the above-mentioned methods to determine the content of granulated blast- furnace slag constituent, limestone constituent and gypsum constituent; calculate the content of each constituent in cement.
Kiln ash is determined in pozzolanic mixed materials or fly-ash constituent, and limestone constituent.
Sandstone is determined in pozzolanic mixed materials or fly-ash constituent. 8.2 Test Procedures
8.2.1 Determination of sulfide in cement and sulfide content in EDTA insoluble slag
The determination of sulfide content (S1) in cement shall be conducted in accordance with GB/T 176.
In terms of the determination of sulfide content (S2) in EDTA insoluble slag, take the filter paper filtered in accordance with 7.2.2 and the insoluble slag out of the glass sand core funnel; place them in the reaction flask for the sulfide determination. In addition, use water to wet the glass sand core funnel; use a wiper to scrub the glass sand core funnel; transfer all the insoluble slag to the reaction flask. Conduct the subsequent steps of determination in accordance with GB/T 176.
8.2.2 Determination of carbon dioxide - burning weighing method
In terms of the determination of carbon dioxide (D1) through the burning weighing method, weigh-take 1 g of specimen (m13), accurate to 0.0001 g; place it in a porcelain crucible that has been burned to a constant mass. Put on the lid on the crucible and leave a gap; place it in a high-temperature furnace (see 5.10). Gradually raise the temperature from a low temperature; at 580 ??C ?? 20 ??C, burn it for 2 h. Then, take out the crucible and place it in the desiccator (see 5.11) to cool to room temperature; weigh it; repeatedly burn it, until it reaches a constant mass (m11). Then, place the above- mentioned specimen in a 950 ??C ?? 25 ??C high-temperature furnace (see 5.10); burn it for about 1 h. Take out the crucible and place it in the desiccator (see 5.11) to cool to room temperature; weigh it; repeatedly burn it, until it reaches a constant mass, or, at The content of clinker constituent in cement (C) shall be calculated in accordance with Formula (13):
Where,
C---mass fraction of clinker constituent in cement, expressed in (%);
P---mass fraction of pozzolanic mixed material or fly-ash constituent in cement calculated in 7.3.4, expressed in (%);
S---mass fraction of granulated blast-furnace slag constituent in cement calculated in 8.3.3 or 7.3.5, expressed in (%);
L---mass fraction of limestone constituent in cement calculated in 8.3.4 or 7.3.6, expressed in (%);
G---mass fraction of gypsum constituent in cement calculated in 8.3.5 or 7.3.7, expressed in (%).
9 Precision
9.1 Repeatability
Under repeatability conditions, when the methods listed in this Standard are used to analyze the same specimen, the difference between the two analysis results shall be within the listed repeatability limits (see Table 2). If the repeatability limit is exceeded, perform the third determination within a short period of time. When the difference between the determination result and the previous two results or any analysis result complies with the stipulations of repeatability limit, then, take the average value, otherwise, find out the reasons and re-conduct the analysis in accordance with the above-mentioned stipulations.
9.2 Reproducibility
Under reproducibility conditions, when the methods listed in this Standard are used to respectively analyze the same specimen, the difference between the average values of the analysis results shall be within the listed reproducibility limits (see Table 2).

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