基于快速碳化试验的混凝土箱梁碳化分析

Analyses on the Carbonation of Concrete Box Girder Based on Accelerated Carbonation Experiment

为研究混凝土箱梁在不同CO_2浓度和反应时间作用下的碳化问题,制作了一组混凝土箱梁模型,将10%、20%两种浓度和14 d、28 d碳化时间组合出4种工况进行了快速碳化试验研究。结果表明,外角部的反应速率与一维碳化的速率比值约为1.56,略高于理论值。通过比较各工况下的碳化程度得出,当CO_2浓度从10%增大20%时,碳化深度增长倍数约为1.2;反应时间从14 d增大到28 d时,碳化深度增长倍数约为1.32,表明在快速碳化试验中,时间对碳化深度的影响大于浓度的影响。随着反应时间的增加,各测点碳化系数均有所下降,表明碳化速率随着反应的进行而减小;随着CO_2浓度的升高,碳化系数趋于稳定。

To study the carbonation problem of concrete box girder under different CO 2 concentrations and reaction times,a set of concrete box girder model were made.The accelerated carbonation experiment was carried out with 4 kinds of working conditions composed by two kinds of concentration(10%,20%),and two phase of carbonization time(14 d,28 d).The results show that the ratio of reaction rate of outer angle part and one-dimensional part is about 1.56,which was slightly higher than the theoretical value.By comparing the carbonization degree under different working conditions,it is concluded that when the concentration of CO 2 increases from 10%to 20%,the carbonation depth growth rate is about 1.2.When the reaction time increases from 14 d to 28 d,the carbonation depth growth rate is about 1.32.It is indicated that the effect of time on carbonization depth is greater than that of concentration in the accelerated carbonation experiment.With the increase of reaction time,each measuring point carbonation coefficient decreased,it s showed that the carbonation rate decreases with the advance of reaction.With the increase of CO 2 concentration,the carbonation coefficient tends to be stable.