Comparative analysis of the effects of three alcohol amine cement grinding aids
Since most of the energy consumption of cement production is in the grinding process, the impact on cement production is mainly compared with the grinding aid effect of the three grinding aids. Many studies and actual production have verified that triethanolamine (TEA) is a good and widely used grinding aid that can increase the grinding efficiency by about 20% when the dosage is 0.01% to 0.03%. Triethanolamine (TEA) and triisopropanolamine (TIPA), both of which increase the specific surface area and the coefficient of wear of the cement. Research on the grinding mechanism. It is generally believed that all three contain both a hydroxyalkyl group and an amine group, and are easily adsorbed on the surface of the particles and in the gaps of the particles, reducing the surface energy of the cement particles, and at the same time, the charge is weakened, thereby being easily broken. At the same time, it also reduces the phenomenon of static electricity accumulation, thereby reducing the phenomenon of over-grinding, reducing the fine particles in the cement, and the particle size distribution is concentrated. Since all three are tertiary amines with hydroxyalkyl groups, the amine nitrogen atoms are respectively connected to three hydroxyalkyl groups, resulting in a low degree of bare pair of electrons on the nitrogen atom, which has strong electronegativity and powder. The steric hindrance of bulk adsorption is large, and the hydroxyalkyl group can be adsorbed on the surface of cement particles; the electronegativity of nitrogen makes it electrostatically repulsive, and the newly generated surface has different charges due to bond breakage after particle breakage. The two can be neutralized to avoid re-aggregation of the new surface and increase the dispersion of the material. Therefore, the cement grinding aids of the three alcoholamines can improve the fluidity of the cement. The longer the hydroxyalkyl carbon chain is, the stronger the ability to adsorb with cement particles. Since the angle of repose of triethanolamine (TEA), diethanol monoisopropanolamine (DEIPA), and triisopropanolamine (TIPA) is getting smaller and smaller, it can be inferred that the ability to increase cement fluidity is: TEA < DEIPA < TIPA .
For the impact on cement properties, TEA is already a mature early strength agent, and research and production have proven that the strength of d1 and d3 increases greatly, but the later d28 is opposite to the blank.
The sample should be low, and the optimum dosage should not exceed 0. 02%. TIPA's research and application are reversed, with no increase in early strength, but can significantly increase the late strength of the milled cement, which can exceed 10%. DEIPA is a combination of early strength and post-strength (more than 10%) and is a good balanced grinding aid, while triethanolamine (TEA), triisopropanolamine (TIPA) and others The use of additives is better. The pair of diethanol monoisopropanolamine (DEIPA) is of great significance in the application of grinding aids. Increasing the compressive strength of the whole age can increase the clinker substitution, reduce the clinker dosage, and increase the amount of mixed materials. The large economic utilization value is conducive to the development of early strength of cement.
Conclusion: (1) Triethanolamine, triisopropanolamine and diethanol monoisopropanolamine are all good cement grinding aids, which have good grinding effect. (2) Triethanolamine has excellent early strength improvement, but can not even weaken the late strength of cement; triisopropanolamine can not promote the early strength of cement, but can improve the characteristics of late strength; diethanol monoisopropanolamine It has the advantages of both, and has obvious improvement on early strength and late strength. (3) Due to the prevalence of chloride salt early strength agents and triisopropanolamine compared with triethanolamine, there are many advantages in terms of dispersibility, age enhancement, application conditions and relative costs, so the application is gradually increasing. , an increasingly widespread replacement of triethanolamine. (4) Diethanol monoisopropanolamine has a strong advantage in cement strength in both early strength and post strength, and will replace triethanolamine and triisopropanolamine. At the same time, diethanol monoisopropanolamine does not pollute the environment during use due to its low toxicity. It is in line with the current trend of low-carbon environmental protection of cement grinding aids, and is a new environmentally-friendly grinding aid.