0 Foreword

In order to further improve the quality of cement in China, promote the green development of the cement industry and fully meet the needs of users,In November 2013, the National Standardization Committee issued the revision plan of GB 175-2007 (20131158-Q-609), which was undertaken by China Building Materials Science Research Institute Co., Ltd.

After more than six years, the standard draft was submitted for review inIn early December 2019, it was reviewed by the National Cement Standardization Technical Committee, and the draft for approval was published on the website of the Ministry of Industry and Information Technology from April 29 to May 29, 2020. For individual opinions during the publicity period, the Department of Raw Materials of the Ministry of Industry and Information Technology organized several coordination meetings and held a technical review meeting in Beijing on December 23, 2021, which was conducted by 31 experts from industry associations, scientific research institutes, design units, colleges and universities, inspection institutions, production enterprises and user representatives. After the meeting, the final GB175 "General Portland Cement" was submitted for approval, it was promulgated on November 27, 2023 and implemented on June 1, 2024.

During the period, respectively.In 2014 and 2018, the strength grade of composite Portland cement 32.5 and 32.5R was canceled in the form of amendment orders No. 2 and No. 3.

In order to optimize the performance of cement and adapt to the development of concrete technology, especially to solve the problem of knowing, measuring and judging cement components to promote the standard production of cement, the revised content of this standard is moreThere are major changes in the 2007 edition. In order to facilitate the smooth implementation of this standard, the provisions of the standard are explained as follows.

1 From article mandatory to full text mandatory.

Reasons for 1.1 enforcement

On January 17, 2020, the State Administration of Market Supervision and Administration promulgated the Measures for the Administration of Mandatory National Standards to strengthen the management of mandatory standards, and clearly pointed out that mandatory national standards should be formulated for the protection of personal health and life and property safety, national security, ecological environment safety and technical requirements to meet the basic needs of economic and social management.

The general Portland cement specified in GB175 is the basic material for engineering construction in China, involving personal health and life and property safety, so it is enforced.

1.2 non-mandatory and negotiable terms

of this standardArticle 6.3 "Alkali content" is not a mandatory clause. When users use alkali active aggregate or have requirements for alkali content, specific indicators can be negotiated.

At the same time, since the standard is the basic requirement for a product, the buyer and seller are allowed to agree on specific technical requirements in the form of a contract to improve product quality and solve the needs of special situations, but only if they comply with the provisions of this standard.

2 Cement components

Components of 2.1 P · Ⅱ Portland Cement

AccordingAccording to the provisions of previous versions of GB175, slag or limestone less than 5% of type P · II Portland cement can be used alone as a mixture, and the two cannot be mixed, as shown in Table 1. However, the content of slag or limestone cannot be "0", otherwise it becomes "P · I".

Table1 Component requirements of Portland cement

 

Components of 2.2 ordinary Portland cement

This standard is revised as follows: the allowable dosage of main mixed materials is greater than or equal6% and less than or equal to 20%, wherein less than or equal to 5% of the alternative mixing material can be used instead of the main mixing material. The main mixed materials here refer to the granulated blast furnace slag/slag powder, fly ash and pozzolanic mixed materials that meet the standards. They can be used alone or in combination with two or three materials. Alternative blend material refers to limestone. See notes a and B in Table 2 for details.

 

Components of 2.3 Slag Portland Cement

In this revision of the standard, the allowable mixing amount of the main mixed material of slag Portland cement and the replacement amount of the replacement mixed material are basically unchanged, but the content in the remarks of the replacement mixed material is deleted.By the words "any material" it is meant that the alternative blending material is one of fly ash or pozzolanic blending material or limestone. After replacement, the content (mass fraction) of slag/slag powder in P. S. A slag Portland cement shall not be less than 21% of the cement mass, and the content (mass fraction) of slag/slag powder in P. S. B slag Portland cement shall not be less than 51% of the cement mass, so as to ensure the basic performance of cement slag cement. See Note c in Table 2.

Table2 Component requirements for ordinary Portland cement, slag Portland cement, fly ash Portland cement and pozzolanic Portland cement

Components of 2.4 fly ash Portland cement and pozzolanic Portland cement

In this revision of the standard, the maximum change in the components of the two is allowed to be less than or equal.5% limestone to replace the main mixed material. After replacement, the content (mass fraction) of fly ash in Portland cement shall not be less than 21% of the cement mass, and the content (mass fraction) of pozzolanic admixture in Portland cement shall not be less than 21% of the cement mass. See Note d in Table 2 for details.

The purpose of allowing limestone to replace the main mixing material is to improve the cement performance by double mixing of the mixing material, but it is not suitable to replace multiple materials, otherwise it will overlap with the composite cement in the cement component.

 

Components of 2.5 composite Portland cement

In order to clarify the difference between composite portland cement and ordinary portland cement, this standard revision redefines composite portland cement: a hydraulic cementitious material made of portland cement clinker and three (inclusive) or more mixed materials as the main components, mixed with an appropriate amount of gypsum grinding. AndThe definition of the 2007 version of the standard is: Portland cement clinker and two (including) or more mixed materials as the main components, mixed with an appropriate amount of gypsum grinding made of hydraulic cementitious materials.

Mixing materials used include granulated blast furnace slag/14 kinds of slag powder, fly ash, pozzolanic mixed materials (5 kinds of natural pozzolanic mixed materials and 5 kinds of artificial pozzolanic materials), limestone and sandstone. At the same time, the provision for alternative mixing materials is eliminated. For the content of limestone, because it is an inert material and the increase of the content will lead to deterioration of cement performance (such as increased brittleness, easy bleeding and sand, etc.), the standard revision gives a limit, that is, less than 15% of the cement quality. See Table 3 for details.

Table3 Component requirements of composite Portland cement

3 Materials for cement production

3.1 Requirements for Clinker

The quality of clinker firing is affected by many factors. The qualified rate of clinker quality control index of any unit cannot be 100%, and occasionally there will be loss on ignition and high free calcium oxide. However, this part of clinker can produce qualified cement products through component adjustment and quality control. Therefore, this standard does not adoptGB/T21372 "Portland Cement Clinker" only stipulates the calcium silicate mineral content and calcium-silicon ratio of clinker for general Portland cement production, but does not limit the loss on ignition, free calcium oxide, magnesium oxide, insoluble matter, sulfur trioxide, etc., and does not require clinker strength.

3.2 Requirements for Natural Gypsum

Original standardThe provisions of "Grade II (inclusive) or above" are mainly for the use of low-grade gypsum for economic reasons. However, in terms of the impact on the performance of cement, the higher the grade of gypsum, the better; at the same time, the higher the grade and the lower the grade of the GB/T5483 "Natural Gypsum" standard, it is easy to lead to misunderstanding. Therefore, the revision of this standard has deleted the provisions of "level 2 (inclusive) and above.

 

3.3 the permitted types of admixtures for general-purpose portland cement in China

Table4 for several international representative countries (or organizations) of the general Portland cement mixed material varieties. It can be seen from this that the mixed materials used are concentrated in three categories: slag, pozzolanic mixed materials and fly ash, with only slight differences. For example, there is no single column of fly ash in the United States (fly ash is a pozzolanic material), the European Union will burn shale (which is a pozzolanic material) and silica ash in a single column, while China will refine pozzolanic materials into 10 kinds and separate columns of limestone and sandstone. Therefore, the variety of mixed materials in China is basically the same as that in the world, or even more.

Table4 Several international representative countries (or organizations) of the general Portland cement mixed material varieties.

3.4 Except for the admixture specified in this standard, other materials cannot be used in the production of general-purpose Portland cement.

For the law, the internationally accepted principle of preparation is."The law can be done without prohibition"; and for standards, the internationally accepted principle of preparation is the opposite of "the law cannot be done without authorization".

Therefore, only the materials specified in this standard and meeting the relevant technical requirements are allowed to be used, and the materials without regulations cannot be used for the production of general Portland cement.

3.5 Requirements for Mixed Materials of Slag, Fly Ash and Pozzolanic

The activity and inactivity of the mixed material are defined according to the degree of participation of granulated blast furnace slag, fly ash and pozzolanic mixed material in the hydration process under specific conditions. Inactive granulated blast furnace slag, fly ash and pozzolanic mixtures also have potential hydraulic or pozzolanic activity, although their contribution to cement strength development is lower, but can also be partially combined in the liquid phase.Ca(OH)2, improve the interface transition zone, optimize the performance of cement; at the same time, even low-activity slag, fly ash, pozzolanic mixed materials can also play a role in the filling of mixed materials, micro-aggregate role, improve and optimize the performance of cement.

In addition, only the United States internationally.ASTM C595 specifies the 45 μm sieve residue, alkali-aggregate reaction, loss on ignition and activity index of the mixture; while Japan only specifies the silica content of the pozzolanic mixture and the basicity coefficient of the slag; Europe specifies the mass sum and basicity coefficient of calcium, silicon and magnesium of the slag, the variety of pozzolanic mixture and the limit of active silica, the loss on ignition of the fly ash and the limit of active silica.

Therefore, in order to make full, reasonable and scientific use of industrial waste slag, this standard revision no longer has any effect on the activity of granulated blast furnace slag, fly ash and pozzolanic mixed materials (such as activity index,28 d compressive strength ratio) for requirements. In addition to the activity level (such as activity index, 28 d compressive strength ratio), other technical requirements shall meet the requirements of relevant standards.

Ammonium ion content in fly ash accordingGB/T397901 "Limits and Test Methods of Ammonium Ion in Fly Ash" for inspection.

 

3.6 to characterize and define the amount of clay in limestone and sandstone with methylene blue values

The 2007 version and the previous GB175 limit the Al2O3 content of limestone for mixing materials, the purpose of which is to limit the amount of clay. Excessive clay mixing will prolong the setting time of cement and reduce the strength of cement. In the case of modern concrete, the compatibility of the cement with the water reducing agent is deteriorated when the polycarboxylate water reducing agent is used.

There are some defects in using alumina to characterize the amount of clay in limestone and sandstone. One is that the content of alumina in clay is different in different regions, and the other is that limestone and sandstone itself will contain a small amount of alumina. Therefore, the international general use of methylene blue value to limit, suchASTM C595, EN197-1, etc., and GB/T 35164-2017 "Limestone Powder for Cement, Mortar and Concrete" promulgated and implemented in 2017 in China also uses methylene blue values.

Therefore, this standard revision adopts the methylene blue value andGB/T 35164-2017 "limestone powder for cement, mortar and concrete" limit of 1.4 g/kg as cement production with limestone, sandstone limit. The methylene blue value shall be tested according to Annex A of GB/T 35164-2017.

3.7 interpretation of sandstone

Sandstone refers to hard sedimentary rocks dominated by quartz sand in geology. Its main minerals are quartz and feldspar.More than 52%, clay minerals in about 15%, goethite in about 18%, other minerals more than 10%. Sandstone is an inert material, which is mainly used in the production of cement to promote the grinding and refinement of clinker and improve the utilization rate of clinker.

Similar minerals to the strictly defined sandstone in geology include quartz sand, quartzite, granite, feldspar, etc. As long as the methylene blue value meets the requirements, it can also be used for the production of general Portland cement, which is of positive significance for the comprehensive utilization of mechanism sand tailings.

4 Chemical composition requirements of cement

Limit of chloride ion in 4.1 cement

With the promotion and increase of cement kiln co-disposal in China and the recycling of industrial water in other industries, the chloride ion content of cement production raw materials has a tendency to increase.When the GB175 draft was solicited for comments, there was feedback that the chloride ion content of cement clinker exceeded 0.06. When revising the standard of GB/T 21371-2019 "Industrial by-product gypsum used in cement", the investigation results showed that the chloride ion content in desulfurization gypsum was as high as 0.15. Therefore, the chloride ion less than 0.06% defined in the original standard has been difficult to achieve in some cases. Therefore, the approval draft (first draft) relaxed the chloride content from 0.06 to 0.1, and retained the "when there is a lower requirement, the buyer and the seller to determine" remarks, in order to meet the special requirements of concrete or engineering.

However, since the relevant mandatory standards for concrete have been promulgated and implemented, the chloride ion content of cement has been limited≤ 0.06, if it is to be relaxed to 0.1, there is a problem of uncoordinated mandatory standards. Therefore, according to the opinion of the technical review meeting on December 23, 2021, the limit of 0.06% is retained to ensure the safety of structural works and highlight the advanced nature of mandatory standards.

Limit of Magnesium Oxide in 4.2 Cement and Steaming Stability

The stability of cement (including boiling stability and steaming stability) is of concern to all parties. If the stability of cement is not qualified, it will lead to the destruction of the engineering structure and cause serious engineering quality accidents. ThereforeASTM standards include autoclaving stability as one of the regular properties of cement (limestone in the United States and India is high magnesium limestone).

As for the influencing factors of cement autoclaving stability, a large number of research results show that it is not only related to the periclase content in clinker, but also related to the enrichment state and crystal size of periclase. Although the local stress caused by the expansion of periclase can be alleviated by large amount of mixed materials, the potential harm is huge if the cooling quality of clinker is not good, and enterprises even illegally use steel slag and other materials containing expansion sources and control only by magnesium oxide content. Therefore, this revision of the standard takes the autoclaving stability as the type inspection item.

At the same time, accordingAccording to the opinion of the technical review meeting on December 23, 2021, strict control should be exercised and the description of 2007 edition should be retained, I .e. the magnesium oxide content in Portland cement and ordinary Portland cement is ≤ 5% (if the autoclave stability of cement is qualified, the magnesium oxide content (mass fraction) in cement is allowed to be relaxed to 6.0); the magnesium oxide content in P · S · A type slag Portland cement, fly ash Portland cement, pozzolanic Portland cement and composite Portland cement shall be ≤ 6% (if the magnesium oxide content (mass fraction) in cement is greater than 6.0, the autoclave stability test of cement shall be carried out and passed).

If the magnesium oxide content in Portland cement and ordinary Portland cement is greater5%,P S A type slag Portland cement, fly ash Portland cement, pozzolanic Portland cement and composite Portland cement have a magnesium oxide content of more than 6%, and autoclaving stability test shall be carried out simultaneously and the autoclaving stability test shall be confirmed to be qualified before leaving the factory. When the magnesium oxide content occurs in the above situation, the entrusting party shall entrust the inspection of the magnesium oxide content and the pressure steaming stability test at the same time when entrusting the inspection or arbitration inspection. If the entrusting party does not entrust the pressure steaming stability test, the entrusted party shall add the pressure steaming stability test and make a comprehensive judgment.

When the magnesium oxide content in Portland cement and ordinary Portland cement≤ 5%, and when the magnesium oxide content in P · S · A type slag Portland cement, fly ash Portland cement, pozzolanic Portland cement and composite Portland cement is ≤ 6%, the manufacturer shall carry out type inspection at least once every six months according to the requirements of type inspection.

4.3 alkali content in cement

When the alkali content in the cement is high, the alkali aggregate reaction will occur in the case of the use of active aggregate, resulting in the structural destruction of the hardened paste, which is the general Portland cement regulations."When using active aggregate and the user requires low-alkali cement, the alkali content in the cement should not be greater than 0.6% or determined by negotiation between the buyer and the seller. In addition, according to a large number of studies, the alkali in cement can promote the hydration of cement to improve the early strength, but there are negative effects such as the compatibility of cement and water reducing agent and the deterioration of the crack resistance of cement concrete. Therefore, in order to improve the crack resistance of concrete, China's CCES01-2004 "Concrete Structure Durability Design and Construction Guide" pointed out that in order to reduce the risk of early cracking of concrete, the alkali content of cement should not exceed 0.6 percent of the quality of cement.

Therefore, reducing the alkali content in cement is one of the measures to ensure the quality of concrete engineering. However, limited to the quality of raw materials such as limestone and clay and mixed materials, the alkali content in cement in China is generally in the rangeWithin the range of 0.8%~ 1.2%, cement with alkali content less than 0.6% needs to be produced by optimizing various raw materials. Therefore, it is not suitable to uniformly stipulate the alkali content of general Portland cement. When users have requirements for alkali content, it shall be determined by negotiation between the buyer and the seller.

5 Physical performance requirements of cement

3 d strength of 5.1 cement

The admixture of the admixture, while optimizing the properties of the cement, also brings earlyThe 3 d strength of slag, fly ash, volcanic ash and composite cement are separately specified with Portland cement and ordinary Portland cement in the previous versions of GB175 in China, and are about 2 MPa lower. This revision of the standard refers to the EN197-1 to simplify the setting of strength indicators. Different cement 3 d strength indicators are no longer set according to cement varieties, but are based on the 3 d strength of Portland cement and ordinary Portland cement, and are set at intervals of 5 MPa. The revised strength requirements are shown in Table 5.

Table5 Strength Requirements for General Portland Cement at Different Ages

Such provisions: to avoid the original standard different varieties of cementConfusion caused by different 3 d strength; Distinguish the differences between different strength grades of cement at intervals of 5 MPa; The improvement of 3 d strength index can inhibit the multi-blending of mixed materials, especially the use of low-quality mixed materials, which is of practical significance for China's cement enterprises to face the reduction of high-quality mixed materials, improve clinker utilization rate and standardize the honest production of cement enterprises.

Characterization and index of 5.2 fineness

1) Meaning and characterization of cement fineness

For the concept of cement fineness, there is a vague phenomenon in China, such as cement enterprises generally set itThe "sieve residue" and the "cement fineness" in the concrete industry are not clear whether it is "sieve residue" or "specific surface area", and some people think that "the content of micropowder in cement is too much".

Cement fineness, as the name implies, refers to the degree of cement thickness, but this is a general concept, there are three ways to characterize-sieve residue, specific surface area, particle distribution (or particle gradation). However, each representation represents a different meaning.

Due to the limitation of the screen aperture, the screen residue can only provide coarse particles larger than a certain particle size (e. g.45 µm, 80 µm) content; specific surface area gives the surface area of cement particles per unit mass, which mainly reflects the fine particle content in cement. Therefore, neither the sieve residue nor the specific surface area can fully describe the fineness of cement. Therefore, when describing the fineness of cement, it should be clear whether it is sieve residue or specific surface area, and it cannot be generally said that cement is coarse or fine. At the same time, attention should be paid to the scope of application of the method for determining the specific surface area of cement: it is not suitable for materials with internal holes, such as fly ash and pozzolanic materials. When the specific surface area is used to characterize the specific surface area of cement containing fly ash and pozzolanic materials, the results obtained include the internal pore specific surface area of the material, resulting in a false high result, which leads to misunderstanding.

Particle distribution (gradation) can fully describe the size and distribution of cement particles. The smaller the characteristic particle size, the finer the cement; the uniformity coefficient characterizes the width of the particle distribution, and the smaller the uniformity coefficient, the wider the cement particle distribution. Therefore, particle distribution (gradation) has become the main parameter to study the reasonable particle distribution of cement.

2) The characterization method of the fineness of ordinary cement should be "expressed by sieve residue"

Cement specific surface area determination method (Blaine method), its scope of application is clearly described in the method standard, not applicable to porous materials and ultrafine materials. In China's current ordinary Portland cement, it is allowed to use mixed materials except for materials without internal holes.-In addition to slag, limestone and sandstone, materials with internal holes can also be used-fly ash (such as unburned carbon) and pozzolanic materials. For ordinary cement containing porous materials, the specific surface area is expressed, and the test results are inflated. Therefore, the original representation of the sieve residue is changed back.

3) Specific surface area index of Portland cement

It is well known that the finer the cement is ground (the larger the specific surface area), the faster and more complete the hydration reaction. However, this corresponds to the negative effects such as a decrease in the degree of compaction of cement particles, an increase in water demand, a slow increase in strength, and an increase in dry shrinkage. The standard consistency water consumption of cement increases linearly with the increase of cement specific surface area, while the dense bulk density decreases rapidly with the increase of specific surface area. Increasing the specific surface area of cement is beneficial to the improvement of cement compressive strength, and the two are basically linear. For dry shrinkage rate, dry shrinkage rate increases with the increase of cement specific surface area.

For the limitation of Portland cement than surface area index, combined with cement than surface area on dry shrinkage, cement standard consistency water consumption, strength and other aspects of the law and amplitude, as well as the current status of China's clinker quality, limit the maximum ratio surface area of Portland cement.400 m2/kg。

At the same time, because the specific surface area mainly reflects the number of fine particles, from the workability of cement, the specific surface area of Portland cement should not be too high, otherwise the rapid hydration of fine particles of clinker leads to increased water demand, shortened setting time, poor compatibility with water reducing agent, poor plasticity. In terms of particle distribution, it is advisable to narrow the particle distribution of Portland cement, reduce the content of fine particles and coarse particles, and give full play to the potential of clinker and save energy and resources in addition to reducing the impact of fine particles on cement performance.

4) 45 μm sieve residue index of other cement

For other cement mixed with admixture, since the particle composition and particle distribution of cement can be optimized by reasonable selection and matching of admixture through selective grinding of different materials, it is appropriate to broaden the particle distribution of cement to realize the close packing of cement particles and thus optimize the performance of cement, such as reducing the water demand of cement, improving the fluidity of slurry and improving the compatibility with water reducing agent. Therefore, this standard revision will be ordinary Portland cement, slag Portland cement, fly ash Portland cement, volcanic ash Portland cement, composite Portland cement fineness.45 m square hole sieve sieve residue said, not less than 5%.

5) For some special needs of users, this standard allows buyers and sellers to negotiate the fineness index value.

6 Determination of cement components

Method for determination of 6.1 components

In order to realize the determination of cement components by the third party, the consistency of the determination method must be solved.GB/T12960 is equivalent to the international method, which is actually adopted by cement enterprises in European countries. At the same time, according to many years of test verification, under the premise of known mixed material types, the cement component error determined by GB/T12960 can be controlled within a certain range. Therefore, the description of other methods with higher precision is deleted in this standard, and GB/T12960 is directly used for inspection.

It should be noted that,GB/T12960 determines the content of mixed materials, while clinker and gypsum are calculated by subtracting the content of mixed materials from 100. Therefore, in the determination of components, it is only necessary to determine whether the amount of mixed material conforms to the provisions of Table 1, Table 2 and Table 3. At the same time, when determining, the measured data is rounded to the nearest whole number.

In order to ensure the accuracy of component control, the manufacturer should use appropriate production procedures and appropriate methods for verification to ensure that the cement components are in accordance.GB/T12960 test in accordance with the provisions of the standard.

 

6.2GB/T12960 Accuracy of determination results

InWhen the standard was revised in 2004, in order to verify whether GB/T12960 could measure the content of mixed materials, the standard revision project team prepared a variety of cement samples with different combinations, and asked the GB/T12960 standard drafting team to use the substitute method for blind sample testing. The results show that when the mixed material is used according to the standard, relatively accurate results can be obtained; when the mixed material is not used according to the standard, the results deviate. According to the GB/T12960 standard development unit for many years of verification research, when cement enterprises according to the standard provisions of the use of mixed materials, the test error is within the control range. In the case of known mixed material varieties, GB/T 12960-2019 gives the repeatability limit and reproducibility limit of the test results, as shown in Table 6.

At the same time, please note that dueThe calculation constant of GB/T12960 component determination is the average statistical value, so the test deviation introduced by the different material properties will become larger, such as the difference between high calcium ash and low calcium ash, the difference between sandstone and pozzolanic mixed materials, the difference between limestone and gypsum grade, etc. In this regard, GB/T12960 gives the correction coefficient of the calculation results of each mixed material to correct the deviation.

Table6 Repeatability limit and reproducibility limit of GB/T 12960-2019

6.3 the knowledge of the variety of mixed materials used in cement production.

The second party can know the variety of mixed materials in cement through quality certification materials (provided with the factory cement) or inspection reports; The third party can know the variety of mixed materials for cement through on-site inspection and quality certification materials during spot check and inspection. When the third party accepts the entrusted inspection (including arbitration inspection), the entrusting party shall provide the variety of mixed materials for cement.

Reliability assurance of mixed material variety in 6.4 quality certification materials or inspection reports

RevisedGB175 is mandatory in full, including cement components and materials. Therefore, third parties (including quality system certification bodies, production license management bodies, quality supervision bodies) and second parties can supervise and confirm whether the information on cement production materials, quality certification materials and inspection reports is true through on-site identification, purchase and sale contracts, raw material quality inspection reports, etc.

7 cement factory

7.1 Quality Confirmation

In view of the lag of the factory inspection of cement products, cement products can be delivered before the factory inspection results come out. But in order to ensure that the quality of the factory cement meets the standard requirements,GB 175-2007 adds the cement factory confirmation system of "the cement factory can only be delivered when the cement indexes and packaging quality meet the requirements.

For"Quality confirmation" is actually carried out by every enterprise from time to time, such as the "outbound management system" of cement enterprises and the "issuance system of laboratory directors.

In order to standardize, cement enterprises should be in the raw material quality inspection, process control, grinding cement quality inspection and previous product quality statistics and analysis on the basis of the development of confirmation procedures and documentation, specific reference can be made.T/CBMF17-2017 to Quality Management Regulations for Cement Production Enterprises.

7.2 ex-factory quality certification materials

Not equivalent to product quality certificate, because some of the data for the confirmation results, so generally referred toThe "quality assurance policy" is a guarantee and commitment to the quality of the products produced. From a legal point of view, the "warranty policy" is one of the components of the contract between the buyer and the seller, but it does not become the basis for the determination of eligibility.

The factory quality certification materials include water-soluble chromium (VI), the type inspection results of the technical indicators such as radioactivity and pressure steaming stability, as well as the inspection results or confirmation results of the factory technical indicators. However, it should be noted that:

(1) The type inspection results shall be updated after the next type inspection.

(2) The confirmation results shall not replace the factory inspection results of the factory cement, and shall be indicated in the materials.

8 Type inspection

Definition of 8.1 type inspection

Also known as routine inspection. It is to conduct a comprehensive test or inspection of various quality indicators of the product according to the product technical requirements, standards or design documents, or the requirements of the product test outline, so as to evaluate whether the quality of the product meets the standards and meets the design requirements, and to conduct data analysis and comprehensive evaluation on the reliability, maintainability, safety and appearance of the product. It is often referred to as type inspection (or type inspection) in the machinery industry, while it is referred to as routine inspection in the electronics industry.

8.2 Type Inspection Organization

When the enterprise has the conditions, it can carry out the type inspection by itself; when the enterprise lacks certain conditions, it can entrust other institutions to carry out the type inspection. Type inspection for the purpose of certification should be entrusted to a qualified third-party inspection agency.

Whether it is carried out on its own or commissioned, the enterprise must conduct a comprehensive evaluation of the test results to confirm whether they meet the standard requirements. Do not meet the standard requirements, shall not organize production or products shall not leave the factory.

Interpretation of 8.3 type inspection conditions

(1) New production

This is a new plant built or new products put into production. It is a prerequisite for enterprises to declare production license.

(2) When the original fuel is changed

For cement enterprises: limestone, clay source changes/The chemical composition of limestone and clay is changed, the disposal waste of cement kiln is changed, and the source/variety of mixed materials is changed;

For grinding stations: change of clinker source, mixed material source/Mixed material variety changes.

(3) When the production process is changed

For clinker firing: the process that affects the thermal system in the kiln and the process that affects the clinker cooling system;

For cement production: grinding equipment and processes.

(4) When the product resumes production after long-term shutdown

As an enterprise since its completion, unless special circumstances will be continuous production. However, at present, due to the requirements of off-peak production and environmental protection, cement enterprises will face frequent shutdown, as short as ten days and a half months, as long as one or two months; at the same time, the northeast and northwest will also periodically stop production in the winter of the off-season construction. Therefore,The above factors should be considered for "long-term product shutdown.

For long-term understanding and judgment, combined with the remarks of type inspection: water-soluble chromium (VI), the inspection of radioactivity and steaming stability, the "long-term" can be defined as six months.

 

Treatment of unqualified 8.4 type inspection

Because type inspection is different from delivery inspection, it is a comprehensive assessment of whether the production equipment, process and raw materials meet the requirements of product standards. It is in the trial production stage after many factors of equipment, process and raw materials change. At this time, it is normal to fail the type inspection.

When the type inspection fails, the cement enterprise shall carry out the following work:

(1) Find and analyze the causes of unqualified products, and take measures to eliminate them, such as: A. Adjust internal control indicators; B. adjust process parameters; C. replace raw materials;

(2) Re-conduct trial production and type inspection.

9 Delivery and acceptance

The 9.1 cement enterprise is obliged to explain to the buyer the mode of delivery and acceptance.

The amount of general Portland cement is wide, involving thousands of buyers and the understanding and mastery of the standard is very different, and the cement enterprise is the first direct user of the standard, the understanding and mastery of the standard should be the best. At the same time, "The seller has the responsibility to inform the buyer of the method of acceptance" falls within the scope of the Civil Law or the Contract Law or the Consumer Rights Law, and is non-technical. As a seller, you should understand the provisions of the Civil Law or the Contract Law or the Consumer Rights and Interests Law, and explain to the buyer the manner and advantages and disadvantages of the acceptance method for the buyer to choose.

9.2 Encourage contractual delivery and acceptance.

The provision of "delivery and acceptance" is the heritage of the planned economy era, which is unique to our country. There is no such provision in any national cement product standard in the world, but it is agreed in the form of a contract.

With the development of China's market economy, the buyer's awareness of rights is improved, and the contract is encouraged to agree on delivery and acceptance.

The contract shall clearly stipulate the cement type, cement composition, technical requirements, acceptance method, arbitration institution in case of quality dispute, arbitration sample, etc.

9.3 The indication on the invoice "based on the inspection report of the manufacturer with the same number of cement" shall be based on the consensus of both parties.

Indicate on the invoice"The inspection report of the producer with the same number of cement as the basis for acceptance" indicates that the model is based on the inspection report of the producer with the same number of cement as the basis for acceptance, which should be based on the consensus reached between the buyer and the seller. Therefore, this standard revision changes it to "If there is no written contract or agreement, or if the acceptance method is not indicated in the contract or agreement, the seller shall notify in writing before shipment and after the buyer's approval, indicate on the invoice" the inspection report of the producer with the same number of cement as the basis for acceptance "".

 

9.4 Arbitration sample and shelf life of cement in case of quality dispute

Due to the uniqueness of cement products-due to the hardening of damp, and the vast territory of our country and the different climate between the north and the south, no country in the world stipulates the shelf life of cement. When the cement is stored for too long or damp is found, it should be re-inspected and the strength grade should be determined according to the re-inspection results before use.

For quality disputes, many occur in the cement factory one or two months or even a year later, such as in the wet and rainy season bagged cement has long been damp or even hardened. Therefore, the arbitration sample can not be taken on site, the sample has long been out of representative, and should be used in the sealed sample approved by both parties.

Duration of 9.5 quality arbitration inspection

In view of the quality inspection cycle of cement products, market circulation and the retention time of sealed samples, the time limit for quality arbitration inspection is as follows: the time limit for acceptance based on the inspection results of the extracted physical samples is as follows40 d; 90 d based on the inspection report of the producer with the same number of cement.

10 ways of packaging

AccordingGB175 provisions, the packaging of cement products can be taken in bulk can also take bags, bags are divided into tons of bags and small bags.

This standard gives the net content requirements for bagged cement andTotal quality requirement of 20 bags. For the packaging form, in the case of consensus between the supply and demand sides can also take other forms of packaging.