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This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 200-2003 Moderate Heat Portland Cement, Low Heat Portland Cement, Low Heat Portland Slag Cement, and the following main changes have been made with respect to GB/T 200-2003:
——The standard name is modified to "Moderate-heat Portland Cement, Low-heat Portland Cement";
——This standard is modified from compulsory standard into voluntary standard;
——The type of "low-heat portland slag cement" is cancelled;
——In the "composition of low-heat portland slag cement", the industrial by-product gypsum and Category A natural gypsum in "gypsum", and the "grinding aid" are cancelled (see Chapter 4; 4.1, 4.4 and 4.5 in 2003 edition);
——Category M natural gypsum is added (see 4.3; 4.4 in 2003 edition);
——Low-heat portland cement with strength grade of 32.5 is added (see Chapter 5);
——Technical requirements for insoluble residue in cement are added (see 6.1.4);
——Technical requirements for tricalcium aluminate, tricalcium silicate and dicalcium silicate in cement are added as selective indexes (see 6.3);
——Technical requirement for 90d compressive strength of low-heat portland cement is added as a type inspection item (see 6.4.5);
——The calculation formulae of mineral composition are modified (see Annex A; and 4.2.3 in 2003 edition).
This standard was proposed by China Building Materials Federation.
This standard is under the jurisdiction of the National Technical Committee on Cement of Standardization Administration of China (SAC/TC 184).
The previous editions of this standard are as follows:
——GB 200-1963, GB 200-1980, GB 200-1989 and GB/T 200-2003.
Moderate-heat Portland Cement, Low-heat Portland Cement
1 Scope
This standard specifies the terms and definitions, composition and materials, code and strength grade, technical requirements, test methods, inspection rules, exfactory, delivery and acceptance, and packaging, marking, transportation and storage of moderate-heat portland cement (hereafter referred to as moderate-heat cement) and low-heat portland cement (hereafter referred to as low-heat cement).
This standard is applicable to the production and application of moderate-heat cement and low-heat cement.
2 Normative References
The following documents for the application of this document are essential. Any dated reference, just dated edition applies to this document. For undated references, the latest edition of the normative document (including any amendments) applies.
GB/T 176 Methods for Chemical Analysis of Cement
GB/T 750 Autoclave Method for Soundness of Portland Cement
GB/T 1346 Test Methods for Water Requirement of Normal Consistency, Setting Time and Soundness of the Portland Cement
GB/T 5483 Natural Gypsum
GB/T 8074 Testing Method for Specific Surface of Cement - Blaine Method
GB/T 9774 Sacks for Packing Cement
GB/T 12573 Sampling Method for Cement
GB/T 12959 Test Methods for Heat of Hydration of Cement
GB/T 17671 Method of Testing Cements - Determination of Strength
3 Terms and Definitions
For the purposes of this document, the following terms and definitions apply.
3.1
moderate-heat portland cement
hydraulic cementing material with moderate hydration heat made of portland cement clinker with proper component and right amount of gypsum through fine grinding
3.2
low-heat portland cement
hydraulic cementing material with low hydration heat made of portland cement clinker with proper component and right amount of gypsum through fine grinding
4 Composition and Materials
4.1 Moderate-heat cement clinker
In moderate-heat cement clinker, the content of tricalcium silicate (3CaO·SiO2, C3S), tricalcium aluminate (3CaO·Al2O3, C3A) and free calcium oxide (f-CaO) shall not be greater than 55.0%, 6.0% and 1.0% respectively.
4.2 Low-heat cement clinker
In low-heat cement clinker, the content of dicalcium silicate (2CaO·SiO2, C2S), tricalcium aluminate and free calcium oxide shall not be greater than 40.0%, 6.0% and 1.0% respectively.
4.3 Natural gypsum
Natural gypsum refers to gypsum or mixed gypsum above Grade 2 (including) of Category G or M as specified in GB/T 5483.
5 Code and Strength Grade
Moderate-heat cement: code: P·MH; strength grade: 42.5;
Low-heat cement: code: P·LH; strength grade: 32.5 and 42.5.
6 Technical Requirements
6.1 Chemical components
6.1.1 Magnesium chloride (MgO)
The content (mass fraction) of magnesium oxide in cement shall not be greater than 5.0%.
If the soundness of cement passes the autoclave test, the content (mass fraction) of magnesium oxide in cement may be up to 6.0%.
6.1.2 Sulfur trioxide (SO3)
The content (mass fraction) of sulfur trioxide in cement shall not be greater than 3.5%.
Foreword I
1 Scope
2 Normative References
3 Terms and Definitions
4 Composition and Materials
5 Code and Strength Grade
6 Technical Requirements
7 Test Methods
8 Inspection Rules
9 Exfactory, Delivery and Acceptance
10 Packaging, Marking, Transportation and Storage
Annex A (Normative) Calculation of Mineral Composition
