Comparison of Aggregate Pore Characteristics as Measured by Mercury Intrusion Porosimeter and Iowa Pore Index Tests
A. Shakoor and C. F. Scholer
Appears on pages(s):
aggregates; durability; freeze-thaw durability; measurement: porosity; quality control
Freeze-thaw durability of concrete aggregates is strongly influenced by the size, shape, and distribution of their pores. Pore characteristics of 30 aggregate samples were investigated first by mercury intrusion porosimetry and then by Iowa pore index test. Many of these aggregates, when used in Indiana pavements, resulted in extensive pitting and popouts in only one severe winter. A comparison of the results of the two tests with field performance of the aggregates studied shows that the pore index test can be used as a reliable, less expensive, and quicker replacement of mercury intrusion porosimetry for predicting aggregate durability. Also, the test results are more representative of the parent rock because of the large volume of the sample involved. Repetition of the test on the same aggregate sample shows that the test is reproducible and gives consistent results. It is concluded that the Iowa pore index method can be used as a quality control test for production run aggregate of varied composition.