辅助胶凝材料对预应力高强混凝土管桩强度及工艺的影响

摘要/Abstract

摘要： 为优化混凝土管桩生产工艺,以硅灰(SF)和偏高岭土(MK)作为辅助胶凝材料,研究硅灰和偏高岭土对不同蒸养时间下混凝土抗压强度的影响,并使用X射线衍射(XRD)和扫描式电子显微镜结合能量色散谱(SEM-EDS)分析其水化产物及微观结构。通过Design-Expert8.0软件设计Box-Behnken试验,以硅灰掺量、偏高岭土掺量和蒸养时间三个因素为自变量,蒸养混凝土抗压强度为响应值,构建多因素回归方程模型。结果表明:硅灰掺量为胶凝材料质量分数8%时,对抗压强度略有提高,提高幅度为6.2%,达到83.6 MPa;5%、8%和10%(质量分数)掺量的偏高岭土均可提高蒸养混凝土的抗压强度,蒸养4 h、8 h、12 h时,10%掺量的偏高岭土对混凝土抗压强度的提升幅度依次为15.6%、13.2%和13.6%,蒸养4 h、8 h和12 h对混凝土抗压强度影响不大。XRD和SEM-EDS结果表明,硅灰和偏高岭土均消耗了Ca(OH)₂,提升了水泥早期水化程度,可以改善内部孔结构。通过响应面法建立模型可以预测,当硅灰质量分数为6.6%、偏高岭土质量分数为10%、蒸养时间为8.6 h时,混凝土抗压强度最高,达到104.8 MPa,且具有较高置信度。

关键词: 混凝土管桩, 蒸汽养护, 硅灰, 偏高岭土, 微观结构, Box-Behnken试验设计

Abstract: To optimize the production process of concrete pipe piles, silica fume (SF) and metakaolin (MK) were used as auxiliary cementitious materials. The influences of silica fume and metakaolin on the compressive strength of concrete under different steam curing time were studied.X-ray diffraction (XRD) and scanning electron microscope-energy dispersive spectroscopy (SEM-EDS) were used to analyze the hydration products and microstructure. The Box-Behnken test was designed by Design-Expert8.0 software, taking silica fume content, metakaolin content and steam curing time as independent variables, the compressive strength of steam curing concrete as the response value, to construct a multi-factor regression equation model. The results show that when the content of silica fume is 8% (mass fraction), the compressive strength slightly increases by 6.2% to 83.6 MPa; the content of metakaolin of 5%, 8% and 10% (mass fraction) improves compressive strength of steam curing concrete. When the steam curing time for 4 h, 8 h and 12 h, the increase of compressive strength of concrete with 10% metakaolin is 15.6%, 13.2% and 13.6% accordingly. The steam curing time of 4 h, 8 h and 12 h has little effect on the compressive strength of concrete. XRD and SEM-EDS results show that both silica fume and metakaolin consume Ca(OH)₂, which improves the early hydration degree of cement and the internal pore structure. The model established by the response surface method predicts that when the mass fraction of silica fume is 6.6%, the mass fraction of metakaolin is 10%, and the steam curing time is 8.6 h, the compressive strength of concrete is the highest with 104.8 MPa, and has a high degree of confidence.

Key words: concrete pipe pile, steam curing, silica fume, metakaolin, microstructure, Box-Behnken experimental design

中图分类号:

TU528

樊祺, 杜红秀, 赵壮. 辅助胶凝材料对预应力高强混凝土管桩强度及工艺的影响[J]. 硅酸盐通报, 2021, 40(8): 2591-2599.

FAN Qi, DU Hongxiu, ZHAO Zhuang. Influences of Auxiliary Cementitious Materials on Strength and Technology of Prestressed High-Strength Concrete Pipe Piles[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2021, 40(8): 2591-2599.

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