Synthesis Of Several Modified Triethanolamine And Its Impact On The Performance Of Cement Application

In the cement industry, a great amount of the total electric energy consumption is consumed in grinding the raw materials and the clinker,and it's convenient to use grinding aids to improve grinding efficiency. The advantage of using aids lies in less investment and improving the quality of cement effectively.The common organic grinding aids currently account alkanol amines and polyhydroxy alcohols,including triethanolamine, diethanolamine,multiglycol and so on.Triethanolamine(TEA),a low tertiary alkanolamines with high polarity, is used for various reasons in cement industry.TEA is a weak base and in an aqueous phase it is mostly in the molecular state.TEA has the ability to chelate with certain metallic ions in highly alkaline media.TEA can increase early strength effectively,but reduce the later strength and the cost is high.The aim of the paper was under the conditions of maintaining the grinding process, to not only increase the early and later strength, but also improve the quality of cement and save energy,with less aids modified TEA with inorganic and organic acids.The content of the present paper was the evaluation of five additives from modified triethanolamine, which were synthesized at a laboratory stage used for Portland cement. To get a valuable result, a reference sample was made with triethanolamine.These compounds were carried out by interground with gypsum and clinker in closed-circuit grinding systems for different concentration and grinding duration.The investigation were performed using the specific surface of the solid, size distribution,D50,uniformity factor"n"and strength.Then, the impact on the grinding effect was discussed.In addition,the hydration phenomenon is investigated by SEM,X-ray diffraction and N2 adsorption.Finally, the action mechanismwas discussed.The results were as follows. (1)At low concentration additives about 0.006%～0.01%,modified triethanolamineclass had substantial grinding advantage in comminution vs. triethanolamine, especially triethanolamine acetate and triethanolamine maleate on cement grindability and strength development, because both of them improved the particle size distribution,especially, increased the grains with the size of 3-32μm.(2)As the main hydration product, C-S-H, its structure trended to change from to long chain to polymericC-S-H.By the XRD analysis it indicated the grinding aids didn't modify the cement hydration products, meanwhile the amount of hydration products increased at the effect of modified-triethanolamine.(3)Morphology of cement paste and the pore structure were analysed at different stages of hydration by SEM and N2 adsorption, which showed the hydration products were more and filled in the internal to make cement paste dense.(4) The action mechanisms of the additives were discussed from both physical mechanical grinding and chemical stimulate.Additives from the modified-triethanolamine class in the subject have good performance, which is expected to be used in cement industry.