摘要
通过静力弯曲荷载作用下的混凝土的快速碳化试验,研究了混凝土碳化深度和p H值的时变特征。通过微观测试方法X射线衍射仪(XRD)和压汞仪(MIP),表征了混凝土在静力弯曲荷载和碳化耦合作用下的固相组成和孔结构变化规律,利用孔表面积分形维数定量表征混凝土孔结构的微观特征。研究结果表明:拉、压应力分别增大和减少了混凝土的碳化深度,且应力越大,碳化深度的改变越大;碳化反应后,氢氧化钙的量明显减少,碳酸钙的量明显增加,其中以方解石形式的增加量最为显著;与未加载混凝土相比,碳化反应前后加载混凝土试件孔隙率均变大,孔表面积分形维数减小,二氧化碳气体的传输系数增加。
Based on accelerated carbonation test of concrete under static bending loads, the time-varying characteristics of concrete car- bonation depth and pH were studied.The solid phase composition and variation of pore structure of concrete under the couple effect of stat- ic bending load and carbonation were characterized by XRD and MIP and the integral pore surface fractal dimension was calculated to quantitatively represent microscopic features.The results show that the tensile stress and compressive stress are able tO increase and de- crease the concrete carbonation depth, respectively, and the larger the changes in stresses, the larger the changes in carbonation depth.After carbonation reaction, the amount of calcium hydroxide decreases while the amount of calcium carbonate increases,specially, the calcite, gains the most significant increment.Compared to unloaded concrete, loading concrete porosity increases and pore surface fractal dimen- sion decreases, which contributes to increasing the transmission coefficient of carbon dioxide gas before and after carbonation reaction.
出处
《混凝土》
CAS
北大核心
2017年第10期45-51,共7页
Concrete
基金
国家重点基础研究发展计划(973计划)(2011CB013800)
国家自然科学基金(51308290)
教育部博士点基金(20133221120004)
江苏省自然科学基金(BK20130947)
江苏省高校自然科学基金(14KJB560008)
江苏省高校自然科学研究重大项目(14KJA560001)
江苏省产学研联合创新资金-前瞻性联合研究项目(BY2014005-05)
关键词
混凝土
碳化
静力荷载
微观结构
试验研究
concrete
carbonation
static load
microstructure
experimental study
