GB/T 748-2023 English PDF (GBT748-2023)
GB/T 748-2023 English PDF (GBT748-2023)
GB/T 748-2023: Sulfate resistance portland cement
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
CCS Q 11
Replacing GB/T 748-2005
Sulfate resistance portland cement
ISSUED ON: MAY 23, 2023
IMPLEMENTED ON: DECEMBER 1, 2023
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 ... 7
4 Materials ... 7
5 Strength grade ... 8
6 Technical requirements ... 8
7 Test method ... 10
8 Inspection rules ... 11
9 Delivery and acceptance ... 13
10 Packaging, marking, transportation, and storage ... 13
Appendix A (Normative) Calculation of mineral composition in cement ... 15 Sulfate resistance portland cement
This document specifies the materials, strength grades, technical requirements, test methods, inspection rules, packaging, marking, transportation, and storage of sulfate- resistant portland cement.
This document applies to the production and application of sulfate-resistant portland cement.
2 Normative references
The following documents contain the provisions which, through normative reference in this document, constitute the essential provisions of this document. For the dated referenced documents, only the versions with the indicated dates are applicable to this document; for the undated referenced documents, only the latest version (including all the amendments) is applicable to this document.
GB/T 176 Methods for chemical analysis of cement
GB/T 749 Test method for determining capability of resisting sulfate corrode 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 6566 Limits of radionuclides in building materials
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 17671 Test method of cement mortar strength (ISO method)
GB/T 21371 By-product gypsum used in cement
GB/T 26748 Cement grinding aids
GB 31893 Limit and determination of the water-soluble chromium (Ⅵ) content for cement
3 Terms and definitions
The following terms and definitions apply to this document.
3.1 moderate sulfate resistance portland cement
A hydraulic material that is made from portland cement clinker with appropriate composition, which is added with an appropriate amount of gypsum and then ground, and can resist the erosion of medium mass concentration sulfate ions (≤2500 mg/L). NOTE: Moderate sulfate resistance portland cement is referred to as moderate sulfate resistance cement, and the code name is P.MSR.
3.2 high sulfate resistance portland cement
A hydraulic material that is made from portland cement clinker with appropriate composition, which is added with an appropriate amount of gypsum and then ground, and can resist the erosion of higher mass concentration sulfate ions ( >2500 mg/L and ≤8000 mg/L).
NOTE: High sulfate resistance portland cement is referred to as high sulfate resistance cement, and the code name is P.HSR.
The portland cement clinker, which is composed of appropriate ingredients, mainly includes calcium silicate, and is obtained from burning the raw meal composed of appropriate ingredients until it is partially melted.
4.2.1 Natural gypsum
It shall comply with the provisions of GB/T 5483.
4.2.2 Desulfurization gypsum
It shall comply with the provisions of GB/T 21371.
4.3 Cement grinding aids
Grinding aids are allowed to be added during cement grinding, and the amount added shall not exceed 0.5% of the cement mass. Grinding aids shall comply with the provisions of GB/T 26748.
5 Strength grade
The strength grade of moderate and high sulfate resistance cement is 42.5. 6 Technical requirements
6.1 Requirements for chemical composition
6.1.1 Magnesium oxide (MgO)
The content (mass fraction) of magnesium oxide is not more than 5.0%.
If the cement passes the autoclave method for soundness, the content (mass fraction) of magnesium oxide in the cement does not exceed 6.0%.
6.1.2 Sulfur trioxide (SO3)
The content (mass fraction) of sulfur trioxide is not more than 2.5%.
6.1.3 Loss on ignition (LOI)
The loss on ignition (mass fraction) is not more than 3.0%.
6.1.4 Insoluble residue (IR)
The content (mass fraction) of insoluble residue is not more than 0.75%. 6.2 Water-soluble chromium (Ⅵ) in cement
Water-soluble chromium (Ⅵ) in cement shall meet the requirements of GB 31893. 6.3 Tricalcium silicate (C3S) and tricalcium aluminate (C3A)
The content of tricalcium silicate and tricalcium aluminate in cement shall meet the requirements in Table 1.
The specific activity of radioactivity shall meet the requirement that the internal exposure index IRa is not greater than 1.0 and the external exposure index Ir is not greater than 1.0.
7 Test method
7.1 Calcium oxide, silicon dioxide, aluminum oxide, ferric oxide, magnesium oxide, sulfur trioxide, loss on ignition, insoluble residue, and alkali content The tests shall be carried out according to GB/T 176. Among them, the alkali content is calculated according to formula (1).
Alkali content = w(Na2O) + 0.658w(K2O) ……………………… (1)
w(Na2O) -- the sodium oxide content in cement;
w(Na2O) -- the potassium oxide content in cement.
7.2 Water-soluble chromium (Ⅵ) in cement
The test is carried out according to GB 31893.
7.3 Tricalcium silicate and tricalcium aluminate
The tests are carried out according to Appendix A.
7.4 Specific surface area
The test is carried out according to GB/T 8074.
7.5 Setting time and boiling stability
The tests are carried out according to GB/T 1346.
7.6 Autoclave method for soundness
The test is carried out according to GB/T 750.
The test is carried out according to GB/T 17671.
7.8 Sulfate resistance
Type inspection items are 6.1, 6.2, 6.3, 6.5, and 6.6.
In one of the following situations, type inspection shall be carried out: -- When a product is newly put into production;
-- When the raw fuel is changed; [Translator’s note: should be the raw material] -- When the production process is changed;
-- When the product production resumes after 6 months of suspension;
During normal production, type inspection shall be carried out at least once a year. Among them, 6.2 and 6.6 shall be carried out at least every six months. 8.3 Judgment rules
8.3.1 Factory inspection
If the test results conform to 6.1, 6.3, and 6.5, the product is qualified. If the inspection result does not meet any of the technical requirements in 6.1, 6.3, and 6.5, the product is unqualified.
8.3.2 Type inspection
If the test results conform to 6.1, 6.2, 6.3, 6.5, and 6.6, the product is qualified. If the inspection result does not meet any of the technical requirements in 6.1, 6.2, 6.3, 6.5, and 6.6, the product is unqualified.
8.4 Inspection report
The content of the inspection report shall include the executive standard, cement type, code, strength grade, factory number, factory inspection items, water consumption for standard consistency, types and dosage of gypsum and grinding aids, and other technical requirements stipulated in the contract. The producer shall send the test results of the specified tests except for the sulfate resistance and 28-d strength within 10 days from the date of cement delivery. Sulfate resistance and 28-d strength values shall be supplemented within 32 d from the date of cement delivery.
8.5 Exit-factory of cement
After the various technical indicators and packaging quality of cement are confirmed to meet the requirements, they can leave the factory.
9 Delivery and acceptance
9.1 The quality acceptance of the cement at the time of delivery can be based on the inspection results of physical samples or the inspection report of the cement with the same number from the manufacturer. The method of acceptance shall be agreed upon by the buyer and the seller, and shall be specified in the contract or agreement. If there is no written contract or agreement, or the method of acceptance is not specified in the contract or agreement, the producer shall inform the buyer in writing before delivery and after the buyer approves, indicate on the shipping order “Acceptance is based on the inspection report of the cement with the same number from the manufacturer”. 9.2 When taking the inspection results of the physical samples as the basis for acceptance, the buyer and the seller shall jointly take samples AND sign and seal them before delivery or at the place of delivery. The sampling method shall be in accordance with GB/T 12573, the sampling quantity shall be 24 kg, and shall be divided into 2 equal parts. One is kept by the seller for 40 days, and the other is inspected by the buyer according to the items and methods specified in this document.
Within 40 days, if the buyer believes that the product quality does not meet the requirements of this document after inspection and the producer has objections, both parties shall send another sealed sample kept by the seller to a third-party cement quality inspection agency recognized by both parties for inspection. The cement stability test shall be completed within 10 days from the date of sampling.
9.3 When the inspection report of the cement with the same number from the manufacturer is used as the basis for acceptance, the producer shall take samples from the cement with the same number before delivery or at the time of delivery. The sampling method shall be in accordance with GB/T 12573, the sampling quantity shall not be less than 14 kg, and shall be divided into 2 equal parts. One is signed and sealed by the producer (or jointly with the buyer) and kept for 90 days, and the other is inspected by the buyer according to the items and methods specified in this document. Within 90 days, if the buyer has doubts about the quality of the cement and the producer has objections, the buyer and the seller shall send the sealed samples jointly approved by both parties to a third-party cement quality inspection agency for inspection. 10 Packaging, marking, transportation, and storage
Cement can be packaged in bulk or in bags, and the packaging form is determined by negotiation between the buyer and the seller. The net content of each bag of cement in bags shall not be less than 99% of the marked mass, and the total mass of 20 randomly