The price of nickel and stainless steel rose together. Nickel afternoon hand in hand with stainless steel together turn red up. Due to the temporary easing of geopolitical risks, risk assets are now picking up, nonferrous metals, stock markets, and so on have risen, the overall mood has temporarily improved. Ore prices are strong, the overlay of the epidemic on spot logistics or the formation of a certain impact. Phase, nickel and stainless steel materials to maintain high wide concussion pattern.
Nickel prices based on low inventory, tight supply and demand will still show high wide fluctuations. In addition, the current LME has low liquidity, so its sensitivity to capital will remain relatively high. Shanghai nickel-wide fluctuations are expected to continue in the 200,000-250,000 yuan wide repeated fluctuation trend. While stainless steel is affected by the stronger nickel pig iron, the cost support continues, but note that under the current demand is not effectively released, the upward space may also be affected, the stage is expected to fluctuate between 20000 and 22,000 yuan. The price of nickel produced such fluctuations, indicating that the price of the concrete water reducer may also be affected to a certain extent.
The water-reducing agent or concrete water reducer is a kind of concrete admixture that can reduce the water consumption under the condition of keeping the slump of concrete basically unchanged. It has a dispersive effect on cement particles, can improve its workability, reduce water consumption per unit, improve the fluidity of concrete mixture, or reduce the amount of cement per unit, saving cement.
Because different cement has different mineralized compositions, in addition to the variety of mixed materials, the effect of admixtures for different types of cement is very different.
In this article, we will talk about the problems when water reducer meets different kinds of cement and solutions.
1. High-alkali Cement
Soluble alkali in cement is usually expressed as Na2O equivalent, which mainly comes from the clay and mixture of cement production. An appropriate amount of soluble alkali is conducive to promoting cement hydration and is more conducive to the early strength development of concrete. The results show that the fluidity of cement concrete increases with the increase of alkali content. However, when a certain amount of cement is reached, the cement will hydrate rapidly and the fluidity of cement slurry decreases greatly. Plasticizing effect decreased obviously after adding water reducing agent. When the water reducing agent is used in the construction of concrete and pumped concrete, the loss rate of slump increases.
It is generally believed that alkali in cement promotes the dissolution of tricalcium aluminate (C3A). At this time, cement forms certain AFt crystals quickly with the help of coagulant CaSO4, which wraps on the surface of C3A, inhibits the direct hydration of C3A to form calcium aluminate, and improves the fluidity of cement slurry. However, if the alkali content in cement is too high, due to the formation of a large number of AFt crystals at the beginning, the fluidity will decrease, and the adaptability of water reducing agent to the above cement will inevitably decrease, for example, the water reduction rate is not enough, the plasticizing effect is poor, and the slump loss rate is high.
For high alkali cement, the effect of the water reducing agent with low sulfate content is poor, while the use effect of higher sulfate content of water reducing agent (sodium sulfate content of more than 20%) will be significantly improved. Primarily, low water reducing agent CaSO4 is contained in the synthesis and production, it has good properties of water-soluble. Gypsum in cement before it a large number of soluble in water, dissolved when higher alkali to speed up the C3A dissolution, because the water has a large number of SO3, reaction with C3A, form the AFt, to prevent the liquidity caused by the formation of calcium aluminate. And the slump loss is reduced. It is not difficult to see, that the water reducing agent with high content of sodium sulfate can adapt to high alkali cement more.
The PH value of many polycarboxylate water reducing agents is low, such as with citric acid and other acid retarder combined with high alkali cement is difficult to adapt. It is mainly because when acid admixture is mixed with cement of high alkali, it can produce acid alkali quickly neutralize exothermic reaction, temperature rises sharply, which not only make cement hydrate rapidly, heat of a large number of hydrate is put more can produce vicious circle, the concrete that place makes up not only fluidity is poor, slump falls to spend very likely disappear inside a very short time. Using other kinds of alkaline retarders can avoid these problems.
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Recently, the first press conference of the Boao Forum For Asia Annual Conference 2022 was held. Two flagship reports were released at the conference: "Asia's Economic Prospects and Integration Process 2022" and "Sustainable Asia and the World 2022-Green Transformation in Action in Asia".
The flagship report points out that the global economy will recover in 2021, and the pace of economic integration in the Asia-Pacific has not stopped even in the face of the impact of COVID-19. The Asia-Pacific region has provided new impetus for the world's economic recovery and institutional building.
The report gives an outlook on the Asian economy, noting that a number of factors will affect Asian economic growth. For example, mutated strains such as Delta and Omicron have become more transmissible, and many economies are experiencing epidemic peaks again. The Ukraine crisis has triggered geopolitical changes in Asia and Europe, leading to higher commodity prices, which may affect the global energy supply and energy transformation.
The report pointed out that the Asian economy will still be in the process of recovery in 2022, but the growth rate may moderate. According to the report, Asia's economic growth in 2022 is likely to be lower than the current IMF forecast, which is projected at 4.8%.
Affected by several factors, the supply of the concrete water reducer is erratic and thus its prices are expected to go higher in the future.
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