| For cement grinding, it has a high energy consumption and low energy utilization. Howere, adding a small amount of grinding aids can improve the grinding efficiency, the cement particle size distribution and the performance of the cement. In this paper, based on the small molecule grinding aids, we synthesized hyperbranched grinding aids using triethanolamine as a core molecule and we conducted a systematic study of its synthesis and properties. This paper Aimed at the development of new hyperbranched cement grinding aids to save energy and improve the performance of cement concrete.Detailed research and experimental results of this paper are as follows:1. Two different types AB2 growth monomer were Synthesized, hyperbranched polyamide- ester(HPE) and hyperbranched polyamine- ester(HPAE)with triethanolamine as core molecule by transesterification and esterification reactions. by controlling the monomer ratio of core molecules and AB2 monomer which is 1: 3,1: 9and1: 21,were synthesized the first generation, second generation and the third generation hyperbranched polymers. Some tests were did on the hyperbranched polymer as FT- IR, elemental analysis, hydroxyl value and TGA. The results showed that the molecular structure of the synthesized hyperbranched consistent to its design, and it can be applied to the field of grinding aids.2. After testing the influence of grinding aids on the fineness of cement we got the best c ontent of hyperbranched grinding aids. The best content of HPE-G1, HPE-G2 and HPAE-G1 was 0.020% and there 45μm sieve residue were reduced by 47.5%, 52.5% and 49.4%. The be st content of HPE-G3, HPAE-G2 and HPAE-G3 was 0.010% and there 45μm sieve residue we re reduced by 48.7%, 50.0% and 46.8%. The best content of HPAE-M was 0.015% and its 45μm sieve residue decreased 48.1%. When in there best content, cement samples which mixed hyperbranched grinding aids rather than triethanolamine had higher specific surface area. parti cle size distribution of the results of the selection The three hyperbranched cement grinding ai ds HPE-G2, HPAE-G2 and HPAE-M were chosed by particle size distribution of which 3-32μm particle content were up 68.8%, 67.9% and 66.4%. And the angle of repose of HPE-G2 and HPAE-G2 were reduced by 32.7% and 25.0%.3. The effect of the aids on hydration of cement was tested. The 3d and 28 d growth rates of compressive strength at the optimum dosage of HPAE-G2 were 18.1% and 30.5%, HPE-M were 15.7% and 28.0% and HPE-M were 26.4%, 29.9%. The setting time of cement samples doped hyperbranched aids was closer to the blank sample, compared with triethanolamine, and the chemically bound water of hardened cement paste of which was higher. There was a maximum promoting on hydration of cement for HPE-M,the chemically bound water content was 22.16% when in 3d and for HPAE-G2,it is 23.32% when in 28 d. By analyzing the XRD patterns and photographs in hydration age of hardened paste in 3d and 28 d, we can see that\hyperbranched aids can not only promote the early hydration of C3 A, but also can promote the 28 d age hydration of C3 S, which was consistent with the fact that hyperbranched aids can improve the mechanical properties of cement.4. The hyperbranched aids synthesized in laboratory had good adaptability with water reducer and good overall performance.It is expected to be used as aids in the production of cement.5. By contrasting with triethanolamine and exploreing the mechanism of alcohol amine groups in the cement grinding and hydration process, we got the mechanism of the enhancement of grinding performance. It was that hyperbranched aids is more easily absorbed in the surface of cement particles to improve the dispersion properties of cement particles, thereby increasing the grinding efficiency, and promoting the cement hydration, and enhancing the grinding performance. |
PDF Full Text Request