摘要
进行4组对比试验,研究密闭与非密闭条件下超高性能混凝土（Ultra-high performance concrete,UHPC）的收缩性能差异,分析不同钢纤维掺量、水胶比及粉煤灰掺量对密闭条件下UHPC自收缩和抗压强度的影响.研究结果表明,UHPC的自收缩和干燥收缩在早龄期阶段发展迅速,14d的自收缩值为114d自收缩值的80%-90%,6d后干燥收缩值不再增长;密闭条件下自收缩值占非密闭条件下总收缩值的82.8%,远大于干燥收缩值;随钢纤维掺量的增加,自收缩值随龄期的变化规律无显著变化,早龄期的自收缩值略微减小,抗压强度呈现先增大后减小的现象;增加粉煤灰掺量或水胶比可以减小自收缩值,但对抗压强度会产生削弱作用;粉煤灰的掺入改变了自收缩值随龄期的变化规律,并产生＂滞后效应＂;基于试验结果对现有的UHPC自收缩预测模型进行了修正,修正后的预测模型可为工程设计提供参考.
This paper investigates the shrinkage behavior of ultra-high performance concrete（ UHPC）. The test parameters are：（ i） curing condition（ sealed or unsealed）,（ ii） steel fiber volume（ 0%,1%,2%,3%,4% and 5%）,（ iii） water-to-binder ratio（ 0. 16,0. 18,0. 20 and0. 22）,and（ iv） fly ash content（ 0%,15%,30%,45% and 60%）. Results from the test indicate that：（ 1） Both the autogenous shrinkage and drying shrinkage of UHPC develop rapidly at early ages. The autogenous shrinkage at 14 days is 80% to 90% of that at 114 days,while the drying shrinkage remains approximately constant after 6 days.（ 2） The effect of curing condition is more significant or autogenous shrinkage（ the autogenous shrinkage under the sealed condition is 82. 8% of that under unsealed condition）.（ 3） The steel fiber volume has no obvious effect on the autogenous shrinkage,but influences the compressive strength of UHPC.（ 4） Increasing the water-to-binder ratio or fly ash content results in the decrease of concrete compressive strength. And（ 5） The fly ash changes the shrinkage responses and results in ＂lag effect＂. The test results are used to modify existing models for predicting the autogenous shrinkage of UHPC. The modified model provides a valuable reference for design.
作者
罗霞
韦建刚
李聪
董锐
陈宝春
LUO Xia;WEI Jiangang;LI Cong;DONG Rui;CHEN Baochun(School of Civil Engineering,Fuzhou University,Fuzhou 350108,China)
出处
《应用基础与工程科学学报》
EI
CSCD
北大核心
2018年第4期830-842,共13页
Journal of Basic Science and Engineering
基金
国家自然科学基金项目(U1305245)
福建省对外合作项目(2015I0012)
关键词
UHPC
抗压强度
自收缩
干燥收缩
密闭
非密闭
模型
UHPC
compressive strength
autogenous shrinkage
drying shrinkage
sealed
unsealed
model
