孔隙水饱和度对混凝土碳化特性的影响

为研究孔隙水饱和度对混凝土碳化特性的影响,提出了孔隙水饱和度预处理方式,设计了孔隙水饱和度为45.8%、58.5%、73.9%、83.8%的四组混凝土快速碳化试验,运用酚酞指示剂法和模拟孔溶液法测试了不同孔隙水饱和度混凝土试件的碳化深度及碳化程度,并建立了基于孔隙水饱和度的混凝土碳化深度影响系数。结果表明,孔隙水饱和度对混凝土的碳化深度具有显著影响,在45%~85%范围内与碳化深度基本成反比关系;对混凝土碳化起决定作用的是孔隙水饱和度,而不是环境的相对湿度,按照《普通混凝土长期性能和耐久性能试验方法标准》进行快速碳化试验时,不宜直接采用外部环境相对湿度表征孔隙水饱和度的影响;孔隙水饱和度对混凝土不同碳化区域碳化程度的影响并不相同,在碳化反应稳定区内碳化反应程度与孔隙水饱和度正相关,而在非稳定区内碳化反应程度与孔隙水饱和度负相关。研究成果为深入分析混凝土碳化特性奠定了基础。

Influence of Pore Water Saturation on Carbonization Characteristics of Concrete

In order to study the influence of pore water saturation on the carbonation characteristics of concrete, the pore water saturation pretreatment method was proposed. The rapid carbonation test of concrete with pore water saturation of 45.8%, 58.5%, 73.9% and 83.8% was designed. The carbonization depth and carbonization degree of concrete samples with different pore water saturation were tested by phenolphthalein indicator method and simulated pore solution method, and the influence coefficient of carbonization depth of concrete based pore water saturation was established. The results show that the pore water saturation has a significant impact on the carbonization depth of concrete, and it is inverse proportional to the depth of carbonization in the range of 45%~85%. It is the pore water saturation instead of the relative humidity of the environment that determines the carbonation of concrete. In accordance with the " standard for test methods of long-term performance and durability of ordinary concrete " for rapid carbonation test, it is not suitable to directly use the relative humidity of external environment to characterize the influence of pore water saturation. The influence of pore water saturation on the degree of carbonization in different carbonation zones is different. The degree of carbonation in the stable zone of carbonation is positive correlated with the pore water saturation, while the degree of carbonation in the unstable zone is negative correlated with the pore water saturation. The research results have laid a foundation for the in-depth analysis of the carbonization characteristics of concrete.