2023, the mandatory national standard GB 175-2023 "General Portland Cement" formulated by the Ministry of Industry and Information Technology was approved and issued by the State Administration of Market Supervision and Administration and the National Standardization Management Committee, and will be implemented on June 1, 2024.
GB 175-2023 "General Portland Cement" is the seventh revision of the General Portland Cement Standard, which embodies the spirit of keeping pace with the times of China's cement production technology standards and construction requirements, and provides a strong technical standard support for promoting the high quality development of the cement industry, which has been submitted for approval and officially published for three years. And the key content has also been changed, which shows that the industry is more controversial about the standard formulation, and it can also be seen that the standard revision is not easy.
The following is a summary analysis of the content and impact of the standard change (according to the interpretation of the GB 175-2023 version currently circulated on the Internet, the official standard will be published 20 days after its release).
on people and the environment GB 175-2007 version of the provisions of chloride ion content, and later in the amendment list to add water-soluble chromium (VI) content requirements, this amendment to the water-soluble chromium (VI) content requirements included in the standard, and did not relax the content of chloride ion, magnesium oxide in accordance with the draft submitted for approval in 2020. At the same time, the mandatory requirements for type inspection such as radionuclide limit and autoclave stability are added to reduce the impact of cement products on the environment and personnel.
Especially in view of the magnesium oxide content index of the mainstream ordinary Portland cement in the market, affected by mine resources, there are many high magnesium mines in the northern region, from the perspective of prolonging mine life and reducing production costs, it should be relaxed to 6%, which is also the focus of the appeal of some enterprises in the industry for many years. Relaxation to 6% does not have much impact on the soundness of cement and concrete. Many foreign cement standards also require below 6%. This standard is still strict and does not relax the magnesium oxide standard of ordinary Portland cement;
In view of the limit value of chloride ion, considering the current co-disposal and other factors, it continues to maintain less than 0.
At the same time, according to the current denitrification of power plants, there are many fly ash with high ammonia ion content in the market, and the requirement that the ammonia ion content in fly ash is not more than 210mg/kg is added.
For limestone and sandstone, the old standard of alumina content should be changed to methylene blue value should not be greater than 1.
The overall feeling is that the standard should be revised cautiously and strictly, and more attention should be paid to the impact on people and the environment.
3. Properly improve the strength to ensure the quality
of cement. Old standard slag Portland cement, fly ash Portland cement, pozzolana Portland cement, composite Portland cement and so on have low compressive strength in three days, in order to add more admixture resources to these cements. Decrease 
Similarly, Portland fly ash cement requires that the minimum proportion of clinker + gypsum is 60%, the proportion of fly ash is not less than 21% and not more than 40%, and only less than 5% of alternative materials (only limestone) are allowed to be added;
Pozzolanic cement and Portland slag cement are specified in detail, so that there will be no pozzolanic cement and Portland slag cement with clinker ratio less than 50% in the future;
The Market Supervision Bureau (Quality and Technical Supervision Bureau) will have the right to go to the factory for inspection and test the cement components, and punish the violators, which will have a serious impact on the cement industry, increase the cost of cement production, and force some small grinding stations to produce products with lower requirements for components. Masonry cement, steel slag Portland cement, magnesium slag Portland cement and other special varieties of cement with lower cost. The advantage of this
clause is that it can standardize the variety and dosage of cement admixture, minimize the amount of clinker, reduce the heavy metal components in some high-temperature smelting waste residues into cement, and guide some cement enterprises to produce special cement varieties. However, it is not conducive to the comprehensive utilization of resources and increases the production cost of enterprises.
At the same time, the specific surface area of the mainstream ordinary Portland cement is changed to be consistent with that of slag Portland cement, fly ash Portland cement, pozzolana Portland cement and composite Portland cement, and the screen residue of the 45μm square hole sieve is changed from not more than 30% to not less than 5%. In short, the fineness index is stricter than previous standard, and it is also to reduce the adverse effects on the adaptability of concrete admixtures, reduce the concentrated release of early hydration heat of concrete, and help to continuously increase the later strength of concrete.
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