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GB/T 21371-2019By-product gypsum used in cement (English PDF)

用于水泥中的工业副产石膏

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Issued by

State Administration for Market Regulation; Standardization Administration of China

Level / Type

National · Recommended

Issue date

October 18, 2019

Implementation date

September 1, 2020

Scope

GB/T 21371-2019 is the English-translated version of 用于水泥中的工业副产石膏.

GB/T 21371-2019 covers industrial by-product gypsum used in cement, the calcium sulfate by-products discharged from industrial manufacturing that are also called chemical or synthetic gypsum.

It gives the terms and definitions, technical requirements, test methods, judgment rules, transportation and storage, and applies to the acceptance and use of such gypsum for adjusting the setting time of cement.

Radioactivity is checked to GB 6566, and the effect on cement is measured by comparing a contrast cement made with natural gypsum against a test cement in which 30 % to 100 % of that gypsum is replaced: consistency, setting time and soundness to GB/T 1346, mortar fluidity to GB/T 2419, mortar strength to GB/T 17671 and compatibility with water-reducing agents to JC/T 1083.

It replaces GB/T 21371-2008, was issued on 18 October 2019 and has applied since 1 September 2020.

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Document preview — GB/T 21371-2019

National Standard of the People's Republic of China

ICS: 91.100.10
Classification: Q 11
Replacing: GB/T 21371-2008

Issued by: State Administration for Market Regulation; Standardization Administration of China

Foreword3
1 Scope5
2 Normative References5
3 Terms and Definitions5
4 Technical Requirements6
5 Test Methods7
6 Judgment Rules8
7 Transportation and Storage9

1 Scope

This Standard specifies the terms and definitions, technical requirements, test methods and judgment rules, transportation and storage of industrial by-product gypsum used in cement.

This Standard is applicable to the acceptance and use of industrial by-product gypsum for adjusting the setting time of cement.

2 Normative References

The following documents are essential to the application of this document. For the dated documents, only the versions with the dates indicated are applicable to this document; for the undated documents, only the latest version (including all the amendments) is applicable to this document.

GB/T 1346 Standard Test Method for Water Requirement for Normal Consistency Setting Time and Soundness of the Portland Cement

GB/T 2419 Test Method for Fluidity of Cement Mortar

GB/T 5483 Natural Gypsum

GB/T 5484 Methods for Chemical Analysis of Gypsum

GB 6566 Limit for Radionuclides in Building Materials

GB/T 17671 Test Method of Cement Mortar Strength (ISO Method)

JC/T 1083 Test Method for Compatibility of Cement and Water-Reducing Agent

3 Terms and Definitions

For the purposes of this Document, the following terms and definitions apply.

3.1 By-product gypsum

The general term for by-products with calcium sulfate as the main component that are discharged from industrial manufacturing.

NOTE 1: Also known as chemical gypsum, synthetic gypsum.

5 Test Methods

5.3 Radioactive material limits

It shall be tested according to GB 6566.

5.4 Influence of industrial by-product gypsum on cement properties

5.4.1 Preparation of contrast cement

It is the P·I Portland cement, which is prepared by the Category-G and Class-2 above (including Class-2) gypsum specified in GB/T 5483, with SO3 content of 2.0%~2.5%, 80µm sieve residue of less than 4%, and specific surface area of 350m²/kg±10m²/kg.

5.4.2 Preparation of test cement

It is P·I Portland cement that is prepared by using Portland cement clinker for preparing contrast cement and by replacing natural gypsum with 30%~100% of the assessed industrial by-product gypsum. During the preparation, the 80µm sieve residue of the cement shall be controlled to less than 4%, the specific surface area shall be within the range of 350m²/kg ± 10m²/kg, and the difference between the SO3 content and the contrast cement SO3 content shall be within 0.2%.

5.4.3 Standard consistency water consumption, setting time and stability of cement

It shall be tested according to GB/T 1346.

5.4.4 Fluidity of cement mortar

The preparation of cement mortar is carried out according to GB/T 17671; and the fluidity test operation of cement mortar is carried out according to GB/T 2419.

5.4.5 Strength of cement mortar

It shall be tested according to GB/T 17671.

5.4.6 Compatibility of cement and water-reducing agent

It shall be tested according to JC/T 1083.

6 Judgment Rules

When any one of 4.1, 4.3, 4.4, 4.5 and 4.6 does not meet the requirements of this Standard, it cannot be used in the manufacturing of cement. […]

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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 12 pages — is available in the English PDF.

Referenced standards

Normative references

Cited by

Similar standards

GB/T 21371-2008|GB 175-2007|GB/T 5484-2012|GB 6566-2010|GB/T 20491-2017|GB/T 203-2008

Editions of GB/T 21371

Edition	Title	Revision	Status
GB/T 21371-2019	By-product gypsum used in cement	first revision	Current
GB/T 21371-2008	By-product gypsum used in cement	first issue	Superseded

This page sells the current edition, GB/T 21371-2019. Earlier editions are listed for reference only.

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