低钙粉煤灰地聚物的流变性能、凝结时间和抗压强度

摘要/Abstract

摘要： 地聚物具有低碳环保的优点,但低钙粉煤灰地聚物存在黏度高、常温凝结时间过长、强度低等问题。本文研究了液固比、碱溶液浓度、减水剂掺量、矿渣掺量等因素对低钙粉煤灰地聚物流变性能、凝结时间和抗压强度的影响。结果表明:新拌地聚物的流变曲线与修正Bingham模型的拟合度较高;屈服应力受矿渣掺量影响最大,随矿渣掺量增大而增大;塑性黏度受液固比影响最大,随液固比升高显著下降。纯低钙粉煤灰地聚物常温凝结缓慢,初凝时间超过8 h,终凝时间超过23 h,当液固比为0.40、碱溶液质量浓度为29%(质量分数)、矿渣掺量为25%(质量分数)时,初终凝时间分别大幅缩短至54、145 min,7 d抗压强度达到23.2 MPa。掺加0.3%~0.5%(质量分数)聚羧酸减水剂后,纯粉煤灰地聚物的28 d抗压强度提高约20%。

关键词: 低钙粉煤灰, 地聚物, 黏度, 屈服应力, 凝结时间, 抗压强度

Abstract: The geopolymer has the advantages of low carbon and environmental protection, but for low calcium fly ash geopolymer, however, there exists some issues including high viscosity, excessively long setting time at room temperature and low strength. The effects of different factors including liquid/solid ratio, alkaline solution concentration, superplasticizer content and slag content on rheological properties, setting time and compressive strength of low calcium fly ash geopolymer were investigated. The results show that the modified Bingham model fits relatively well with the rheological properties of fresh geopolymer. Yield stress is affected most by slag content, and increases with the increase of slag content. Plastic viscosity is affected most by liquid/solid ratio, and decreases significantly with the increase of liquid/solid ratio. The setting process is rather slow for pure low calcium fly ash geopolymer at room temperature, and the initial setting time is over 8 h and the final setting time is over 23 h. When liquid/solid ratio is 0.40, alkaline solution concentration is 29% (mass fraction) and slag content is 25% (mass fraction), the corresponding initial and final setting time are 54 and 145 min, respectively, and the 7 d compressive strength is 23.2 MPa. Adding 0.3%~0.5% (mass fraction) polycarbonate superplasticizer, the 28 d compressive strength of pure fly ash geopolymer increases by around 20%。

Key words: low calcium fly ash, geopolymer, viscosity, yield stress, setting time, compressive strength

中图分类号:

TU526

杨孟君, 曹义冬, 林常, 徐树英, 潘莉莎. 低钙粉煤灰地聚物的流变性能、凝结时间和抗压强度[J]. 硅酸盐通报, 2023, 42(5): 1721-1730.

YANG Mengjun, CAO Yidong, LIN Chang, XU Shuying, PAN Lisha. Rheological Properties, Setting Time and Compressive Strength of Low Calcium Fly Ash Geopolymer[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2023, 42(5): 1721-1730.

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