GB/T 176-2017Methods for chemical analysis of cement (English PDF)

4.1 Number of tests and requirements

The number of tests for each determination is specified as two; the absolute difference between the two results is within the repeatability limit (Table 3, Table

4, Table 5). The average value of the two test results is used to indicate the determination result.

4.2 Representation of mass, volume, titer and results

Mass is expressed in "grams (g)" and is accurate to 0.0001 g. The volume of the burette is expressed in "milliliter (mL)"; the reading is accurate to 0.01 mL.

The titer is expressed in "milligrams per milliliter (mg/mL)".

4.3 Repeatability limit and reproducibility limit

The repeatability limits and reproducibility limits listed in this standard are absolute deviations, expressed in terms of mass fraction (%).

4.7 Checking chloride (silver nitrate inspection)

After washing the precipitate several times as required, use water to rinse the lower end of the funnel; continue using water to wash the filter paper and the precipitate; collect the filtrate in a test tube; add a few drops of silver nitrate solution (6.1.31); observe whether the solution in the test tube is turbid. If it is turbid, continue washing and testing until it is no longer turbid when checking by the use of silver nitrate.

4.8 General requirements for reagents

Unless otherwise specified, the reagents used shall not be lower than analytical grade; the reagents used for calibration shall be reference reagents. The water used shall not be lower than the requirements of the third-grade water as specified in GB/T 6682.

6.1 Reagents and materials

6.1.1 Hydrochloric acid (HCl)

1.18 g/cm3 ~ 1.19 g/cm3, mass fraction is 36% ~ 38%.

6.1.2 Hydrofluoric acid (HF)

1.15 g/cm3 ~ 1.18 g/cm3, mass fraction is 40%.

1.12 g/cm3, mass fraction is 99%.

6.1.12 Ethanol

The volume fraction of ethanol is 95%.

6.1.13 Absolute ethanol (C2H5OH)

The volume fraction of absolute ethanol is not less than 99.5%.

6.1.14 Glycerol [C3H5 (OH) 3]

The volume fraction is not less than 99%.

6.1.18 Nitric acid (1 + 1); (1 + 2); (1 + 9); (1 + 100)

6.1.19 Sulfuric acid (1 + 1); (1 + 4); (1 + 9); (5 + 95)

6.1.20 Phosphoric acid (1 + 1)

6.1.21 Acetic acid (1 + 1)

6.1.22 Formic acid (1 + 1)

6.1.23 Ammonia (1 + 1)

6.1.24 Ethanol (1 + 4)

6.1.25 Triethanolamine (1 + 2)

6.1.26 Sodium hydroxide (NaOH)

6.1.34 Ammonium molybdate solution (50 g/L)

Dissolve 5 g of ammonium molybdate [(NH4) 6Mo7O24 · 4H2O] in hot water; after cooling, add water to dilute it to 100 mL; store it in a plastic bottle; if necessary, filter it before use. This solution is used within one week.

6.1.35 Ascorbic acid solution (5 g/L)

Dissolve 0.5 g of ascorbic acid (V.C) in 100 mL of water; if necessary, filter it before use. Prepare it before use.

6.1.47 Potassium periodate (KIO4)

6.1.48 Sodium hydroxide solution (200 g/L)

Dissolve 20 g of sodium hydroxide (NaOH) in water. Add water to dilute it to 100 mL. Store it in a plastic bottle.

6.1.55 pH 4.3 buffer solution

Dissolve 42.3 g of anhydrous sodium acetate (CH3COONa) in water; add 80 mL of glacial acetic acid; add water to dilute it to 1 L. After preparation, use a precision pH test paper to check.

6.1.56 Potassium fluoride solution (20 g/L)

Place 20 g of potassium fluoride (KF · 2H2O) in a plastic cup; add water to dissolve it; add water to dilute it to 1 L; store it in a plastic bottle.

6.1.57 Ammonium oxalate solution (50 g/L)

Dissolve 50 g of ammonium oxalate [(NH4) 2C2O4 · H2O)] in water; add water to dilute it to 1 L; if necessary, filter it before use.

6.1.58 Potassium sodium tartrate solution (100 g/L)

Dissolve 10 g of potassium sodium tartrate (C4H4KNaO6 · 4H2O) in water; add water to dilute it to 100 mL.

6.1.59 pH 10 buffer solution

Dissolve 67.5 g of ammonium chloride (NH4Cl) in water; add 570 mL of ammonia; add water to dilute it to 1 L. After preparation, use a precision pH test paper to check.

6.1.77 Manganese monoxide (MnO) standard solution

6.32.3 Calculation and representation of results

The mass fraction of chloride ion wCl- is calculated according to formula (53).

6.33.3 Calculation and representation of results

The mass fractions of potassium oxide and sodium oxide wK2O and wNa2O are calculated according to formula (54) and formula (55), respectively.

6.34.2 Analytical procedures

Take solution C in 6.11.2.1 directly; use an atomic absorption spectrophotometer (6.2.15);

6.34.3 Calculation and representation of results

The mass fraction wMnO of manganese monoxide is calculated according to formula (56).

6.35.2 Analytical procedures

Weigh about 0.2 g of specimen (m47), accurate to 0.0001 g; put it in a 100 mL dry beaker; add 10 mL of water to disperse the specimen;

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