复合超细粉煤灰混凝土的徐变性能

CREEP CHARACTERISTICS OF CONCRETE WITH COMPOUND ULTRA-FINE FLY ASH

用对比实验方法系统研究了原材料组成、养护制度以及加载龄期等因素对强度等级为C50的复合超细粉煤灰(compound ultra fine fly ash,CUFA)混凝土和C50普通混凝土徐变的影响规律,并分析了相应的影响机理。结果表明:相同条件下,CUFA混凝土徐变比普通混凝土的显著降低;与碎卵石相比,用碎石能够降低CUFA混凝土的徐变度,但骨料品种对普通混凝土的徐变度影响不明显。养护制度对CUFA混凝土的徐变度有较大影响,蒸汽养护条件下CUFA混凝土的徐变度显著降低。适量CUFA的掺入对蒸汽养护混凝土微观结构的改善作用较标准条件养护的混凝土更加显著,较大幅度地降低了混凝土的干燥徐变。CUFA混凝土的徐变度无论是在10d还是28d加载,其徐变度约在持荷60～90d后趋于稳定。

In order to understand the factors influencing the creeping of concrete with compound ultra-fine fly ash （CUFA）, the creep behavior of C50 concrete with CUFA and C50 ordinary portland concrete were tested by parallel experimental methods. The influence of composition, curing system and loading age on creep behavior were investigated, and the corresponding mechanism was discussed. The results indicate that the creeping of concrete with CUFA is lower than that of ordinary portland concrete in the same conditions. Compared with crushed pebbles, crushed stones can better reduce the specific creep of concrete with CUFA, but the type of aggregate did not appear to influence the specific creep of ordinary portland concrete. The curing system has a great influence on the specific creep of concrete with CUFA. Under steam curing conditions, the specific creep of concrete with CUFA is lower than that under moist curing conditions. The addition of CUFA into concrete can remarkably improve the microstructure and reduce dry creep. The specific creep of C50 concrete with CUFA becomes stable after 60-90 days＇ loading, whether the loading age is 10 d or 28 d.