With the formal implementation of the new national standard GB 175-2023 "General Portland Cement" on June 1 this year, it has also had a wide and far-reaching impact on the development of the concrete industry. This not only promotes the improvement of material quality, but also accelerates the green and low-carbon transformation of the concrete industry.
This standard revision cancels the requirement of alkali content and takes it as a selective index. When the alkali content of concrete is too high, alkali-aggregate reaction may occur, which causes the damage of concrete structure, uneven expansion, cracks and so on, endangering the safety of the project. The standard stipulates that "when the user requests to provide low-alkali cement , it will be determined by the buyer and seller through consultation", which will promote closer cooperation between concrete enterprises and cement suppliers. Although it may increase the cost pressure in the short term, it will accelerate the survival of the fittest within the concrete industry in the long run.
This standard strictly regulates the cement fineness, which ensures the stability of cement quality and the improvement of concrete strength and durability to a certain extent. Too high or too low cement fineness will affect the strength and durability of concrete. When the fineness is too high, the reaction between cement particles is too fast, and too much water is consumed, which leads to the difficulty in ensuring the later strength of concrete and premature cracks; when the fineness is too low, the porosity of concrete will increase and the durability of concrete will be affected.
This standard clearly defines the types and proportions of admixtures, aiming at improving the performance, stability and adaptability of admixtures of concrete. Reasonable specification of cement admixtures (such as fly ash, slag, etc.) can stabilize the performance of concrete, such as reducing the phenomenon of thermal expansion and contraction, improving the impermeability of concrete, etc.; the use of admixtures within the specified range, its activity, water demand, mineralized composition is relatively fixed, stabilizing the adaptability of admixtures and cement, reducing the procurement cost of concrete enterprises.
Of course, the most important thing is that the implementation of the new national standard for cement not only promotes the standardization of the upstream market of concrete, eliminates backward cement production capacity, but also reduces the phenomenon of cement products with uneven quality levels flowing into the market, guarantees the quality and safety of concrete projects, and promotes the high-quality and sustainable development of the upstream and downstream industrial chain of concrete.
In the current concrete industry to the road of green low-carbon transformation, the road of carbon reduction in the industry has also begun to become multi-dimensional.
As the main source of carbon emissions in concrete production, the carbon emissions of cement account for about 90% of the total emissions. The first strategy is to start from the source and choose low-carbon cement, such as sulphoaluminate cement and ecological cement, which have shown remarkable results in reducing the overall carbon footprint of concrete.
At the same time, it can also improve the mixing amount of fly ash in the concrete preparation process , optimize the mix proportion, reduce the demand of cement in each cubic concrete, not only reduce the carbon footprint, but also optimize the hydration heat performance of concrete, reduce shrinkage and other advantages;
Finally, the structural design and construction can be optimized to improve the durability of concrete, prolong the service life, and reduce the demand for maintenance and reconstruction, which is the key to achieve carbon emission reduction in the long run. This strategy not only reduces the environmental burden, but also reduces the long-term cost, which embodies the core value of green building concept.
