粉煤灰水泥基材料的水化产物

用热重仪-差示扫描量热仪、扫描电子显微镜、透射电子显微镜、X射线能量散射、高分辩电子显微镜、压汞仪，测定了粉煤灰水泥基材料水化产物的形貌特征、微观结构、化学组成及水泥石的孔结构，讨论了水化产物性质及水泥石孔结构随粉煤灰掺量的变化规律。结果表明：粉煤灰的大量掺加，可以改善凝胶的化学组成。水化后期，粉煤灰与Ca(OH)2及由熟料水化生成的高n(Ca)／n(Si)的水化硅酸钙(C—S—H)凝胶发生二次水化反应，生成低n(Ca)／n(Si)的C—S—H凝胶，此种凝胶的固碱能力强，可减少碱-集料反应的危害性。同时，二次水化产物能够填充那些对水泥石强度和耐久性极为不利的孔隙空洞，使水泥石的结构更加致密，优化水泥石的孔结构，对提高水泥基材料的耐久性作用极大，为进一步提高工业废渣利用的技术水平奠定了基础。

HYDRATION PRODUCTS OF FLY ASH CEMENT-BASED MATERIAL

Morphology, microstructure, chemical composition of hydration products, and pore structure for cement pastes with different fractions of fly ash were investigated by thermogravimetrydifferential scanning calorimetry, scanning electron microscope, transmission electron microscope, energy dispersive X-ray analysis, high-resolution transmission electron microscope, and mercury intrusion porosimetry. Effects of different dosages of fly ash on characteristics of hydration products and pore structure were also discussed. Results show that the chemical composition of CSH gel can be improved by doping in larger fraction of fly ash. In late of hydrate stage, fly ash reacts with Ca(OH)_2 and CSH gel with high molar ratio of CaO and SiO_2 to produce CSH gel with lower molar ratio of CaO and SiO_2, which is called secondary pozzolanic reaction. The CSH gel can bind more alkali to alleviate alkali-aggregate reaction. The second pozzolanic reaction products can also fill in the pores, those are disadvantage to the strength and durability of cement paste. It can optimize the pore structure of cement paste to make the cement structure denser, which is helpful to the durability of concrete.