摘要
对膨胀剂掺量(质量分数)为4%,8%和12%的3种钢管混凝土(CFST,concrete filled steel tube)在含钢率(面积分数,钢管与混凝土的截面面积比)为3.8%,4.1%,6.6%,9.2%和10.8%的5种情况下进行了徐变性能试验.结果表明:膨胀剂掺量为4%时钢管混凝土徐变度最大,掺量为8%时徐变度次之,掺量为12%时徐变度最小;膨胀剂掺量12%相比膨胀剂掺量8%时的钢管混凝土徐变度下降并不显著;含钢率的增加有效分担了钢管混凝土的外部荷载,使其徐变度有所减小.应用扫描电镜(SEM)观测及能谱仪(EDS)分析得出膨胀剂的作用机理:膨胀剂反应生成钙矾石,一方面通过钙矾石的微膨胀补偿了收缩;另一方面钙矾石填充在结构孔隙中,使水泥石更加密实.分析含钢率对钢管混凝土徐变性能的影响机理后认为混凝土应力随着含钢率的增加而减小,原因是含钢率的增加使得钢管对混凝土的约束也有所增加,由此限制了混凝土的变形.
Experiments with expanding agent proportion（by mass） of 4 %, 8% and 12 % were carried out re spectively in order to clarify the effects of expanding agent proportion and steel ratio on concrete filled steel tube（CFST）＇s creep characteristics. The results show that 4% of expansive agent additive affects the creep degree most, the 8 % of expanding agent additive does less, and the t 2 % of expansive agent additive does the least. When addition of expanding agent was decreased from 12 % to 8 %, the creep degree of concrete filled steel tube was slightly decreased. By means of SEM and EDS the action mechanism of expanding agent was clarified. The analysis revealed that expanding agent reacts with concrete to produce ettringite. On the one hand it may compensate shrinkage by slight expansion. On the other hand it may fill in pores and made dense for hardened cement. The concrete filled steel tube with tube wall thickness of 3.8%, 4.1%, 6.6 %, 9.2 and 10.8 % were prepared. It is shown that the exterior loads are shared with the increase of steel ratio. The creep degree is decreased. The steel ratio affects CFST creep mechanism on the same loading condition. The study concludes that the stress in concrete decreases along with increasing steel ratio. With the increase of wall thickness, steel would be binding the concrete and limiting the deformation of concrete.
出处
《建筑材料学报》
EI
CAS
CSCD
北大核心
2015年第5期749-756,共8页
Journal of Building Materials
基金
国家自然科学基金资助项目(51268032)
长江学者和创新团队发展计划(IRT1139)
兰州交通大学青年科技基金资助项目(2012026
2012028)
关键词
钢管混凝土
膨胀剂
含钢率
徐变
机理
concrete filled steel tube（CFST）
expanding agent
steel ratio
creep
mechanism
