早龄期受硫酸盐侵蚀下的混凝土分层腐蚀模型

The Layered Corrosion Model of Concrete under Sulfate Attack at Early Age

为研究早龄期受硫酸盐侵蚀下混凝土的损伤劣化规律,采用压汞法(mercury intrusion porosimetry, MIP)测定了清水环境和硫酸盐环境下不同腐蚀龄期混凝土试样的孔隙率,利用分光光度法测定了混凝土中硫酸根离子的分布,并测试了不同腐蚀龄期混凝土的超声波声速值。结果表明:清水组中混凝土的孔隙率先降低后逐渐趋于一个定值,硫酸钠溶液中混凝土的孔隙率则先降低后增加;混凝土超声波声速值的变化规律与孔隙率的变化规律呈负相关性。最后,结合硫酸根离子的分布规律和Fick第二定律,建立了腐蚀混凝土分层理论计算模型,并利用混凝土密实速率系数评估了混凝土的损伤劣化进程。

In order to study the damage and deterioration of concrete under sulfate attack at early age,the porosity of concrete samples with different corrosion ages in clear water environment and sulfate environment was measured by the mercury intrusion porosimetry(MIP)test.Then the distribution of sulfate ions in the concrete was measured by the spectrophotometric method.The ultrasonic velocity of concrete with different corrosion ages was measured.The results show that the porosity of concrete in clear water group firstly decreases and then gradually tendes to a fixed value,and the porosity of concrete in sodium sulfate solution firstly decreases and then increases.The variation law of the ultrasonic velocity of concrete is negatively correlated with the variation law of porosity.At last,combined with the distribution law of sulfate ion and Fick s second law,a Stratified-Theoretical model of corroded concrete is established.Then the coefficient of concrete compaction rate of corrosion layer is calculated and the results are consistent with the deterioration process of concrete.