复合改性再生混凝土抗氯离子渗透性能

提出了粉煤灰和纳米SiO2的复合改性方法,使用质量取代法,研究了粉煤灰和纳米SiO2单掺及复掺对再生混凝土(RAC)抗氯离子渗透性能(84d)的影响。结果表明,再生粗骨料全部取代天然粗骨料会显著降低抗氯离子渗透性能,84d氯离子迁移系数和电通量分别提高了101.7%和89.1%;单掺SiO2或粉煤灰时,随着取代率的提高抗氯离子渗透性能越好。复掺纳米SiO2和粉煤灰能够产生叠加效应,显著提高RAC的抗氯离子渗透性能,其中复掺2%纳米SiO2与30%粉煤灰时84d氯离子迁移系数和电通量分别降低了72.3%和89.1%,甚至优于普通混凝土,并且相同掺量的纳米SiO2对30%的粉煤灰改性效果更好。

Study on Chloride Penetration Resistance of Compound Modified Recycled Concrete

A method to modify recycled aggregate concrete (RAC) by combining Nano-silica and fly ash was put forward, and the effect of Nano-silica and fly ash on iron penetration resistance (84 d) of RAC was investigated using mass substitution method to replace natural aggregate (NA) by recycled aggregate (RA). Results show that RA can decrease the ability of concrete to resist iron penetration significantly, the coefficient of chloride migration and electric flux increased 101.7% and 89.1% respectively. Using Nano-silica and fly ash alone can intensify the resistance to iron penetration with the increase of dosage. Moreover, combination of Nano-silica and fly ash can perform excellent synergistic effect on resistance to iron penetration better than single effect of both of them. Among them, combining 2% Nano-silica and 30% fly ash reduce the coefficient of chloride migration and electric flux by 72.3% and 89.1% at curing age of 84 d respectively.