摘要
为研究粉煤灰掺量对钢-聚丙烯纤维混凝土抗冻性能的影响,设计并制备6种粉煤灰替代率的混杂纤维混凝土,对其进行冻融循环及盐冻循环试验,测试其质量损失、相对动弹模量及弯曲韧性。基于热力学模型计算冻融前后混凝土孔结构分形维数,建立分形维数与混凝土弯曲韧性之间的关系。结果表明:当粉煤灰质量掺量为5%~15%时,随粉煤灰掺量增多,混杂纤维混凝土的抗冻性能明显提升;继续增加粉煤灰掺量至20%,混杂纤维混凝土的弯曲韧性开始降低。混杂纤维混凝土内部孔具有明显的分形特征,分形维数与无害、少害孔总孔隙占比及多害孔孔隙占比均有良好的线性相关性。同时,混杂纤维混凝土孔分形维数与峰值荷载、能量吸收值呈正相关,分形维数越大,混凝土所能承受的峰值荷载越高、能量吸收值越大。
In order to study the influence of fly ash content on the frost resistance of steel-polypropylene reinforced concrete,five kinds of hybrid fiber concrete with fly ash replacement rate were designed and prepared.The freeze-thaw cycle and salt-freeze cycle tests of concrete were carried out,the law of mass loss,dynamic modulus and bending toughness of the concrete as freeze-thaw cycles increase had been analyzed.Based on the thermo-dynamic model,the pore structure fractal dimension of concrete before and after freeze-thaw was calculated,and the relationship between fractal dimension and concrete bending toughness was established.The results show that when the fly ash content ranges from 5%to 15%,with the increase of fly ash content,the frost resistance of hybrid fiber concrete is improved obviously.With the increase of fly ash content to 20%,the residual flexural toughness of hybrid fiber concrete begins to decrease.The internal pores of hybrid fiber concrete have obvious fractal characteristics,and the fractal dimension has good linear correlation with the total pore proportion of harmless and less harmful pores and the pore proportion of more harmful pores.At the same time,the fractal dimension of the fiber reinforced concrete is positively correlated with the peak load and energy absorption value.The larger the fractal dimension is,the higher the peak load and energy absorption value the concrete can bear will be.
作者
王春晓
董建明
李得胜
WANG Chunxiao;DONG Jianming;LI Desheng(China Highway Engineering Consultants Group Co.,Ltd.,Beijing 100089,China;Key Laboratory for Special Region Highway Engineering of Ministry of Education,Chang’an University,Xi’an 710064,China)
出处
《硅酸盐通报》
CAS
北大核心
2021年第11期3608-3616,共9页
Bulletin of the Chinese Ceramic Society
关键词
混凝土
混杂纤维
粉煤灰
冻融循环
分形维数
弯曲韧性
concrete
hybrid fiber
fly ash
freeze-thaw cycle
fractal dimension
bending toughness
