Correlation Between Pore Size Distribution and Freeze Thaw Durability of Coarse Aggregate in Concrete.

摘要

Studies have shown that the pore characteristics of coarse aggregates have an important role in the freeze-thaw durability of concrete. This study was designed to seek a correlation between pore-size distribution of an aggregate measured by mercury intrusion and the freeze-thaw durability of concrete made with the aggregate. Fourteen aggregates with a variety of pore-size distributions were studied. The rapid freeze-thaw (ASTM C 666A) and a modified critical dilation test were conducted. The absorption and the PCA absorption-adsorption tests were also conducted. A good correlation between the pore-size distribution of an aggregate and its normalized durability factor obtained from the rapid freeze-thaw test was found. The equation relates the expected durability factor to the total pore volume and the median pore size. Larger pore volumes and smaller pore sizes make for poor durability. Aggregates from pavement concrete with varying degrees of D-Cracking were run and,on the basis of the results,tentative expected durability factors were set up to distinguish between potentially good and potentially poor aggregates. Absorption values and the absorption-adsorption test were not as good indicators of performance.