碱对粉煤灰水泥早期电阻率、孔结构和微观结构的影响

INFLUENCE OF ALKALINE ON ELECTRICAL RESISTIVITY,PORE STRUCTURE AND MICROSTRUCTURE OF FLY ASH CEMENT AT HYDRATION EARLY AGE

采用无接触电阻测量方法,测定电阻率随水化时间的关系曲线,研究了粉煤灰水泥中加入NaOH和Na_2SO_4后净浆水化早期电阻率的变化规律。结果表明:加入NaOH后,水化初期电阻率减低,后期电阻率增加:加入Na_2SO_4后也显示出此规律。电阻率的变化曲线能够显示粉煤灰持碱效应的变化。采用水银挤入实验和扫描电镜对粉煤灰水泥的水化结构进行了研究,表明适量NaOH的加入,能够减少粉煤灰水泥的累计孔体积和总孔隙率,水化结构更加致密。

The relationship curves between electrical resistivity and hydration time were measured by the non-contact electrical resis- tivity method, and the rules of changes in early hydration time in fly ash cement with the addition NaOH and Na2SO4 were investi- gated. The results show that after the addition of NaOH, in the earlier hydration period, the electrical resistivity decreased, however, in the later period, the electrical resistivity increased. The addition of Na2SO4 followed a similar rule. Through the electrical resistivity curves of different hydration times, the absorption effect of fly ash on alkaline can be studied. The hydration structure was studied by a mercury intrusion pore test and scanning electron microscopy. The results indicated that with the addition of the appropriate amount of NaOH, the cumulative pore volume and total porosity in fly ash cement decreased and the hydration structure was more compact.