摘要
自收缩是引起低水胶比高性能混凝土早期开裂的主要原因。通过不同掺量粉煤灰混凝土自收缩的测定，研究粉煤灰对高性能混凝土自收缩的抑制作用。通过水化结合水和内部孔含量的测定以及微观结构形貌分析，研究粉煤灰抑制自收缩的作用机理。研究表明：粉煤灰通过改变胶凝材料体系水化速度、徐变系数、弹性模量，可以有效抑制早期混凝土的自收缩。粉煤灰掺量在0～20％范围内，混凝土自收缩随着粉煤灰掺量的增加而减少，但粉煤灰惨量超过20％后自收缩减少的幅度变小。粉煤灰抑制自收缩的作用在初凝至1d龄期内非常突出。
Autogenous shrinkage is the main reason that makes high performance concrete （HPC） with a low water-binder ratio crack at early age. Through measuring autogenous shrinkage of HPC with different content of fly ash, fly ash restraints on autogenous shrinkage were studied by experiments in this paper. In the meanwhile the mechanism was studied by measuring hydrated water and pores inside and analysis of micro-structure. The research shows that fly ash could restrain early autogenous shrinkage by changing the parameter of binder, such as hydrated velocity, creep coefficient, elastic modulus and so on. In the range of 0-20% contents, the more the addition of the fly ash is, the less the autogenous shrinkage would be, although shrinkage decrease becomes slowly when fly ash content is more than 20 %. The effect is very clear especially from initial setting to 1 d age.
出处
《中国铁道科学》
EI
CAS
CSCD
北大核心
2006年第4期27-31,共5页
China Railway Science
基金
国家自然科学基金资助项目(10102002)
关键词
高性能混凝土
自收缩
粉煤灰
抑制
机理
High performance concrete
Autogenous shrinkage
Fly ash
Restraint
Mechanism
