混凝土成熟度和氯离子扩散系数的相关性及在某工程中的应用

Correlation of chloride diffusion coefficient and concrete maturity value and its application in marine engineering

采用化学结合水法、氯离子快速测定法(RCM法)和混凝土成熟度测定法研究了56 d龄期内混凝土氯离子扩散系数和混凝土成熟度的关系。结果表明:混凝土氯离子扩散系数不仅随养护龄期的延长而降低,还随养护温度的升高而降低,延长养护龄期或提高养护温度均可提高胶凝材料的水化程度;室内养护混凝土试件的氯离子扩散系数与混凝土成熟度值之间呈幂函数关系,二者具有很好的相关性(R^2=0.976),利用室外养护混凝土试件的数据进行验证计算,其理论计算值与实测值具有较好的吻合性,可根据混凝土成熟度实测值预测出混凝土的氯离子扩散系数;在本工程中,沉管隧道接触海水时混凝土成熟度的推荐值为21 064℃·h,控制边界值为13 926℃·h,考虑外部养护温度和水化热对混凝土成熟度产生影响时,可对混凝土接触海水的龄期通过后计算进行适当的调整。

The correlation of chloride diffusion coefficient and concrete maturity value within 56 days of curing was investigated by the chemically combined water content method, rapid chloride migration（RCM） test and concrete maturity test, respectively. The experimental results showed the chloride diffusion coefficient of concretes decreased with increasing curing ages and curing temperature, which can promote the hydration degree of cementious. There was a significant correlation between the chloride diffusion coefficient of indoor curing specimens and the concrete maturity value when expressed as a power function （R2=0.976）, and the calculated values of concrete maturity for outdoor specimens which obtained by using the power function agrees well with the measured values, then it can use the measured concrete maturity value to predict the chloride diffusion coefficient of concrete. The recommended value and the control value of concrete maturity was 21 064 ℃·h and 13 926℃·h, when the immersed tube tunnels were placed in seawater. Furthermore, the ages of the tunnels placed in seawater can be appropriately adjusted by calculation when considering the external curing temperature and heat of hydration of cementious.