Edit this cement grinding aid.
brief introduction
Cement grinding aid is a chemical additive. Adding a small amount in the cement grinding process can improve the grinding process. In order to improve grinding efficiency, reduce power consumption, improve the fineness of cement powder and cement strength, a small amount or a small amount of grinding AIDS are added in the grinding process without changing the existing process and equipment conditions of the factory, which affects the mechanical force of grinding operation. Cement grinding aid is a small product in the cement industry chain, but it plays a very important role in increasing production and reducing consumption in the cement industry, which can bring tangible benefits to cement enterprises. In the mid-1980s, China successfully developed three series of more than ten kinds of grinding AIDS, which are suitable for different kinds of cement grinding. Under the condition of constant specific surface area, the output of grinding machine increases10% ~ 20%; Mineralizer improves the yield and quality of clinker calcination; Retarder improves the quality and performance of cement and becomes an indispensable additive in cement production. With the improvement of construction engineering technology, ordinary concrete can no longer meet the needs of different construction technical conditions, and people have developed additives that can change various properties of concrete. Such as: preparing high-quality high-strength concrete, shortening the construction period, speeding up the construction, meeting the construction requirements under special conditions, realizing the horizontal and vertical pumping of concrete, and developing commercial concrete produced on a large scale by centralized industrialization, and so on; Admixtures make the workability of concrete arbitrary. Admixtures have become the fifth basic component after cement, sand, stone and water. The special research results of cement and concrete additives and their technical and economic significance, the implementation experience of factories and sites, the production process practice of cement enterprises after the implementation of new cement standards, the selection of some national standards and industry standards, etc. It will certainly play a positive role in promoting the correct and standardized understanding and use of additives for cement enterprises, cement products and construction departments in China.
function
1. Without changing the conditions of the cement mill, change the dispersity of materials in the mill, effectively eliminate the electrostatic adsorption and ball paste grinding of cement fine particles, and optimize the gradation of cement particles. 2. Under the condition of keeping the same cement strength grade, using the same cement clinker and admixture and adjusting their proportions appropriately, the cement clinker can generally be reduced by 6- 10% after adding cement grinding AIDS, and the total amount of admixture can be increased by 6- 10%. 3. Keeping the original mill output unchanged and improving the fineness and specific surface area of cement powder can increase the cement strength by 20% in 3 days and 10% in 28 days; Or keep the existing fineness and specific surface area of cement powder, which can improve the output of cement mill by more than 10%. Cement grinding AIDS can also bring direct economic benefits to cement enterprises: electricity consumption per unit area of cement, grinding body consumption, mill liner consumption and maintenance costs are correspondingly reduced, productivity is improved, production scale of enterprises is expanded, and costs are reduced. At the same time, the use of cement grinding AIDS can improve the fluidity of cement, improve the efficiency of classifier, reduce the caking phenomenon of cement, and correspondingly reduce the time and cost of cement loading and unloading.
dosage
(1) All enterprises that use cement grinding AIDS know that each variety of cement grinding AIDS has its optimal dosage, and the dosage of liquid products is generally 0.03%-0. 15% (the dosage of liquid products in our company is generally between 0.08%-0. 10%), with wide dosage range and price. The dosage of powdered products is generally 0.5%- 1%, which is large in quantity and low in price. In fact, adding less grinding AIDS can't achieve good results, and adding more grinding AIDS can't increase much effect. Cement enterprises should pursue products with high cost performance. Therefore, cement grinding AIDS enterprises should have professional R&D personnel and professional technical service teams to do a good job of "consulting" marketing for cement plants, tailor-made according to the characteristics of different technologies, equipment and mixtures of different enterprises, and achieve win-win and common development with cement enterprises. In the market of China, powder was basically produced and sold by domestic manufacturers in the past. Due to the restriction of the new cement standard on the dosage and chloride ion, many manufacturers began to produce liquid products. However, quite a few manufacturers are still producing powder products. According to the investigation and analysis of domestic powdery cement grinding AIDS, the main components of these powdery additives are chloride and sodium sulfate. Some so-called "grinding AIDS" actually have no grinding AIDS. The table shows the composition of powdered cement grinding AIDS produced by some domestic manufacturers. As we all know, chlorine salt and sodium sulfate have a good activation effect on additives. The author has done a lot of research work in this field, and made a very systematic study on their mechanism of action and their influence on microstructure and properties. These research results have been published in famous foreign journals, and have been widely recognized and cited in the international cement concrete field. Adding chlorine salt and sodium sulfate to cement will cause some potential hazards. Their effects on the properties of cement concrete are described below. High chloride ion content in cement concrete will cause corrosion of steel bars and lead to cracking and damage of concrete. It is reported that about 80% of concrete durability problems are related to steel corrosion. Therefore, many countries in the world have made strict regulations on chloride ion content in cement, and cement production enterprises and cement concrete admixture production enterprises are also more conscious. Europe stipulates that the chloride ion content in all kinds of cement should be less than 0. 1%, and the chloride ion content in cement for prestressed concrete should be strictly controlled. Japan stipulates that the chloride ion content in ordinary cement should be less than 0.035%, and the chloride ion content in early strength, ultra-early strength, moderate heat, low heat and sulfate-resistant cement should be less than 0.02%. China's national standard "General Portland Cement" (GB 175-2007) was officially implemented on June 1 day this year. The requirement that "grinding AIDS ≤0.5% are allowed to be used in cement production, and the chloride ion content in cement must be ≤0.06%" has been added to the new cement standard. The original dosage of grinding AIDS is about 0.8- 1.0%. If the content of NaCl is 30%, the addition of chloride ion in the grinding aid is 0. 15-0. 18%. Even if the dosage can be reduced to 0.5% now, the amount of chloride ion or sulfate ion added in cement remains unchanged. Coupled with the chloride ion content in cement clinker and admixture, the chloride ion content in cement will far exceed the specified amount in the new cement standard. (2) The alkali-aggregate reaction and the limit of alkali content in cement. As we all know, alkali in cement can react with active aggregate to expand, and even lead to concrete cracking and damage. Therefore, in many major projects, the alkali content of cement used is limited to below 0.6%. The dosage of powdered grinding AIDS is about 0.8- 1.0%. When the content of NaCl is 30%, the addition of Na2O in the grinding aid is 0. 16-0.20%. If it still contains 30% Na2SO4, it will be further increased by 0. 10-0. 13. The United States paid little attention to alkali aggregate at the peak of construction. As a result, in the 1980s and 1990s, a large number of cases of concrete structure damage caused by alkali-aggregate reaction were found all over the country, and now everyone is "discoloring at the sight of alkali". Many investigation results show that aggregates in many areas of China have alkali activity, and cases of concrete structure damage caused by alkali-aggregate reaction are common. Therefore, when adding Na2SO4 to cement, the potential consequences should be considered. (3) The phenomenon of pan-alkalization and the reverse shrinkage of concrete strength. Adding sodium sulfate to cement sometimes leads to alkalization, and when the dosage is high, it will also lead to the reverse shrinkage of strength at 28 days and after. Although there is no direct regulation on sodium sulfate in cement concrete, many countries, regions or engineering projects have strict regulations on alkali. The influence of sodium sulfate on the performance of concrete is various.
Type and model
Types of cement grinding AIDS (1)A, G2 grinding AIDS (Jingmen Vocational and Technical College, Lin Yumei) A- organic reagents; G2- industrial waste liquid (2)KPY99 cement grinding aid (Nanhua Cement Co., Ltd.) (3) CBA110 cement additive (Grace Company): CBA110 cement additive contains Soluble compounds composed of CB 1 10 and iron leave the surface of cement particles in aqueous solution and then are separated from B 1 10. Free CB 1 10 molecules return to the surface of cement particles and further combine with iron in C4AF hydrate. Therefore, as long as there is unhydrated C4AF phase and water, CB 1 10 will always promote the hydration reaction of cement, make the hydration of cement particles more complete and give full play to the strength of cement. (4)TM grinding aid (South China University of Technology): It is mainly composed of three substances: A is a sodium salt with good grinding aid effect, B is a nonionic surfactant, and C is a salt with grinding aid enhancement effect. They are compounded according to a certain proportion, the concentration is 40%, the pH is 8 ~ 9, and the density is1.14g/cm3 (5) BT-2000 multifunctional cement activation grinding aid (6) Xinjiang Tianshan Cement Co., Ltd. Use: CGA grinding aid (7) as cement grinding aid (School of Chemistry and Chemical Engineering, Central South University): B- nonionic surfactant; C salt, with grinding aid and strengthening effect. TM is composed of A, B and C in a certain proportion, with a concentration of 40% and a density of 1. 14g/cm3. (9)LT2003 grinding aid (South China University of Technology): Surfactants A and B, industrial waste liquid C, acid and alkali are prepared according to a certain proportion and procedure, with a concentration of 40%, PH=8 and a density of 1. 12g/cm3. (10)HM 1002 grinding AIDS (Jinan Jinxiangyuan Science and Technology Development Co., Ltd.): (1 1)DF grinding AIDS (China Institute of Building Materials, Heep Company) (12) BD 99/kloc-.
Edit this paragraph of grinding AIDS.
The main raw materials commonly used in powder grinding AIDS are triethanolamine (grinding AIDS), industrial salt (which leads to excessive chloride ion), arsenic trioxide and sodium sulfate (which is easy to crystallize). Fly ash is used as the carrier and is produced after being mixed evenly. The production process of 1% powder grinding aid: 2.5-3% of Zhi Heng grinding aid mother liquor, 5- 10% of industrial salt, 0/0-/0/5% of quicklime powder (lime) and 77% of carrier (fly ash, stone powder or water residue).
Edit this paragraph of liquid grinding AIDS.
The general process of liquid cement grinding aid formula: triethanolamine, sec-Bo polymer polyol, triisopropanolamine, ethylene glycol, propylene glycol, sugar ether (also known as molasses and orange water, which is used to color or improve the workability of cement/adjust setting time, and has an enhancing effect), sodium acetate (also known as sodium acetate), dodecyl benzene (to improve the flow rate), calcium chloride, sodium sulfate, etc. , stir evenly in a fixed container, and then put it into a bucket. In recent years, polymer synthetic grinding AIDS have also appeared, mainly polycarboxylic acids, but the incompatibility between polycarboxylic acid grinding AIDS and naphthalene concrete additives restricts their rapid development. 0. 1% liquid grinding aid production process: Zhi Heng grinding aid mother liquor 20%, anhydrous calcium chloride 20-25%, water 55-60%.
Edit the development prospect of this paragraph.
The formula of grinding AIDS is not a once-and-for-all formula, which needs to be scientifically tested, compared with different clinker and different mixed materials, and summed up experience. The implementation of the new cement standard has given a shot in the arm to the transformation of grinding aid industry, and the transformation from powder grinding aid to liquid grinding aid is imperative. The technology of liquid grinding AIDS has developed rapidly. Recently, universities and some grinding aid enterprises are developing new grinding AIDS, some of which are synthesized by polymers, and the grinding aid industry will usher in a prosperous situation. In 2007, China Cement Association established the Cement Grinding Aids Branch, which indicated that the development of China's cement grinding AIDS industry entered the fast lane of standardized development!