目前研究表明混合材对碱-硅酸反应(ASR)有很好的抑制作用,但对混合材抑制ASR机理的认识需进一步完善。本文采用TEM／EDS、FT-IR和29Si MAS NMR等现代测试方法对不同粉煤灰掺量的水泥基材料主要水化产物C-S-H凝胶化学组成和结构进行研究...目前研究表明混合材对碱-硅酸反应(ASR)有很好的抑制作用,但对混合材抑制ASR机理的认识需进一步完善。本文采用TEM／EDS、FT-IR和29Si MAS NMR等现代测试方法对不同粉煤灰掺量的水泥基材料主要水化产物C-S-H凝胶化学组成和结构进行研究,指出了低Ca／Si比的C-S-H凝胶在抑制ASR中的重要作用(能够结合孔溶液中的碱,减少可发生ASR的有效碱量),并分析了低Ca／Si比的C-S-H凝胶的持碱机制,对混合材抑制ASR的机理有了新的认识, 完善了混合材抑制ASR的机理。研究结果不仅对于建立比较完整的碱一集料反应预防理论是十分必要的,而且对于抑制和防止碱集料反应具有一定的指导意义。展开更多
The effect of fly ash on controlling alkail-silica rection （ASR） in simudated alkali solution was studied. The expausion of mortar bars and the content of Ca（ OH）2 in cement paste cured at 80 °G for 91 d were...The effect of fly ash on controlling alkail-silica rection （ASR） in simudated alkali solution was studied. The expausion of mortar bars and the content of Ca（ OH）2 in cement paste cured at 80 °G for 91 d were measured. Traasmission electron microscopy （TEM） and high-resolution transmission electron microscot9 （HRTEM） were employed to study the microstructure of C-S-H. TEM/ energy dispersive spectroscopy （EDS） leas then used to determine the composition of C-S-H. The pore structure of the paste was analyzed by mercury intntsion porosimetry （MIP）. The results show that the contents of fly ash of 30% and 45% can well inhibit ASR. And the content of Ca（OH） 2 decreases with the increase of fly ash. That fly ash reacted with Ca（OH）2 to produce C-S-H with a low Ca/Si molar ratio could bind more Na^＋ and K^＋ ious, and produce a reduction in the amount of soluble alkali available for ASR. At the same time, the C- S- H produced by pozzolanic reaction converted large pores to snudler ones （ gel pores smaller than 10 nm ） to deusify the pore structure. Perhaps that could inhibit alkali trausport to aggregate for ASR.展开更多
文摘目前研究表明混合材对碱-硅酸反应(ASR)有很好的抑制作用,但对混合材抑制ASR机理的认识需进一步完善。本文采用TEM／EDS、FT-IR和29Si MAS NMR等现代测试方法对不同粉煤灰掺量的水泥基材料主要水化产物C-S-H凝胶化学组成和结构进行研究,指出了低Ca／Si比的C-S-H凝胶在抑制ASR中的重要作用(能够结合孔溶液中的碱,减少可发生ASR的有效碱量),并分析了低Ca／Si比的C-S-H凝胶的持碱机制,对混合材抑制ASR的机理有了新的认识, 完善了混合材抑制ASR的机理。研究结果不仅对于建立比较完整的碱一集料反应预防理论是十分必要的,而且对于抑制和防止碱集料反应具有一定的指导意义。
基金Founded bythe National Basic Research Programof China"973"(No.2001CB610706)
文摘The effect of fly ash on controlling alkail-silica rection （ASR） in simudated alkali solution was studied. The expausion of mortar bars and the content of Ca（ OH）2 in cement paste cured at 80 °G for 91 d were measured. Traasmission electron microscopy （TEM） and high-resolution transmission electron microscot9 （HRTEM） were employed to study the microstructure of C-S-H. TEM/ energy dispersive spectroscopy （EDS） leas then used to determine the composition of C-S-H. The pore structure of the paste was analyzed by mercury intntsion porosimetry （MIP）. The results show that the contents of fly ash of 30% and 45% can well inhibit ASR. And the content of Ca（OH） 2 decreases with the increase of fly ash. That fly ash reacted with Ca（OH）2 to produce C-S-H with a low Ca/Si molar ratio could bind more Na^＋ and K^＋ ious, and produce a reduction in the amount of soluble alkali available for ASR. At the same time, the C- S- H produced by pozzolanic reaction converted large pores to snudler ones （ gel pores smaller than 10 nm ） to deusify the pore structure. Perhaps that could inhibit alkali trausport to aggregate for ASR.
