Freeze-thaw durability of high-performance concrete masonry units

A high-performance concrete masonry unit (CMU) was developed at the University of Nebraska's Center for Infrastructure Research to replace the standard 38-lb unit used in modern construction. High-performance units were produced from several different trial mixes. This paper presents the results of tests performed to determine the durability of the units as compared to standard normal-weight concrete masonry units. The units were tested for absorption under ASTM C 140 and for freeze-thaw durability by a test adapted from the ASTM C 666 standard for cast-in-place concrete. High-performance units that were made with normal-weight aggregates had somewhat lower absorption rates than standard units, but the freeze-thaw durability was reduced. High-performance units produced with lightweight aggregates had absorption results comparable to standard normal-weight units. The freeze-thaw durability of these units was varied, and for some of the units it was superior to that of standard normal-weight units. Admixtures were used in some mixes to increase durability and lower absorption. A lightweight mix that used a waterproofing admixture to precoat the aggregate before mixing resulted in the most durable units under freeze-thaw testing. These units also had very low absorption rates.