ENVIRONMENTAL FACTORS INFLUENCING THE DURABILITY OF CONCRETE STRUCTURES IN FROST ENVIRONMENTS

摘要

The present study concerns the quantification of the environmental factors influencing the durability of concrete structures under on-site frost environments, including the number of freeze-thaw cycles, average freezing rate and time proportional coefficient of water saturation in concrete. A statistical method is put forward to get the on-site freeze-thaw cycles by using the average annual number of negative-temperature days as an index. In addition, a practical formula is obtained to predict the natural freeze-thaw cycles accordingly. Then, a conceptual approach considering the time proportion of concrete in saturated condition is proposed for general atmospheric environment. According to the average freezing rate in the freezing and thawing, the proportional coefficient of concrete damage in different freezethaw environments is obtained. Based on the aforementioned factors, relationship between different freeze-thaw environmental conditions is established. As an example, procedure of predicting the equivalent number of laboratory freeze-thaw cycles from on-site freeze-thaw cycles is given. Thus, the relationship between on-site environment and indoor experiment is established.