摘要
为分析长期荷载作用下粉煤灰混凝土抗碳化性能的尺寸效应,在相对湿度为(70±5)%,CO2体积分数浓度为(20±3)%,温度为(20±2)℃环境中,研究了粉煤灰等质量替代水泥为0、30%、60%,水胶比为0.45,40 mm×40 mm×160 mm(以下称为小试件)、70.7 mm×70.7 mm×212.1 mm(以下称为中试件)、100 mm×100 mm×400 mm(以下称为大试件)的混凝土试件经标准养护28 d后,在相对湿度(60±5)%,温度(20±2)℃(以下称为干养护)条件下,放置3 a的空载试件、加载试件(压应力水平为33%)的快速碳化情况,基于粉煤灰混凝土的工作性能分析了其在3 a压应力作用下抗碳化性的尺寸效应。结果表明:长期压应力作用可减缓粉煤灰混凝土的碳化进程,对于小试件影响较为明显,而对于大试件则不显著,中试件介于大小试件之间;对于不掺粉煤灰的混凝土试件,3 a压应力作用下混凝土抗碳化性能的尺寸效应与3 a龄期空载混凝土相差不大;对于粉煤灰混凝土,3 a龄期压应力作用及3 a龄期空载条件下粉煤灰混凝土抗碳化性能的尺寸效应系数(L值)随着粉煤灰掺量的增加而降低,但两者L值的比值基本保持不变,这表明在研究荷载作用对粉煤灰混凝土抗碳化性能的影响时可以用小试件模拟大试件进行试验,但应注意尺寸效应系数的影响。
In order to analyze the size effect of anti-carbonization performance of fly ash concrete under long-term load,the paper studies the quality replacement cement of fly ash in the environment of relative humidity(70±5)%,CO2 volume fraction concentration(20±3)%,temperature(20±2)℃,the quality replacement cement such as fly ash is 0,30%,60%,water cement ratio is 0.45.After the concrete specimens with 40 mm×40 mm×160 mm(hereinafter referred to as small test piece),70.7 mm×70.7 mm×212.1 mm(hereinafter referred to as the pilot piece),100 mm×100 mm×400 mm(hereinafter referred to as large specimens)are cured for 28 days,the dimension effect of carbonation resistance under the action of 3 a compressive stress is analyzed based on the working performance of fly ash concrete.The results show that long-term compressive stress can slow down the carbonation process of fly ash concrete,and it has obvious influence on small specimens,but not for large specimens,and the medium-sized specimens are between large and small ones;For concrete specimens without fly ash,the size effect of carbonation resistance of concrete under 3 a compressive stress is not different from that of 3 a-year-old concrete;For fly ash concrete,the size effect coefficient(L value)of the carbonation resistance of the fly ash concrete decreases with the increase of the fly ash content,but the ratio of the L value of the two is basically unchanged.This shows that small specimens can be used to simulate large specimens when studying the influence of load on the carbonation resistance of fly ash concrete,but the effect of size effect coefficient should be taken into account.
作者
安赛
何小军
张立娟
AN Sai;HE Xiao-jun;ZHANG Li-juan(Hebei Normal University of Science & Technology,Qinhuangdao,Hebei 066004;Shijiazhuang Institution of Railway Technology,Shijiazhuang,Hebei 050041;Hebei Institute of Architecture and Civil Engineering,Zhangjiakou,Hebei 075000)
出处
《河北建筑工程学院学报》
CAS
2021年第1期86-91,共6页
Journal of Hebei Institute of Architecture and Civil Engineering
基金
河北省高等学校科学技术研究青年基金项目(QN2020204)
河北科技师范学院海洋学科专项资助项目(2018HY015)
河北科技师范学院教学研究项目(JYZL201902)。
关键词
粉煤灰混凝土
3
a龄期
压应力
尺寸效应
碳化
fly ash concrete
3 a age
Compressive stress
Size effect
carbonization
