Creep and Shrinkage of Lightweight Concrete

In 1989-1990 a study was conducted at North Carolina State University to determine the shrinkage and creep potential of concrete made with expanded slate aggregate [10]. As part of this study, elastic modulus and other standard plastic concrete characteristics were also determined. Four separate concrete mixes were produced for this study. One mix was a conventional concrete using normal weight coarse aggregate for comparison, two mixes were “standard lightweight” mixes and the fourth mix was a relatively high strength mix. 

The author (Leming) noted that values of creep and shrinkage strain for these lightweight concretes were low compared to national (United States) averages. He also noted that values of the elastic modulus were significantly higher than predicted by the American Concrete Institute equations based on compressive strength and unit weight. He noted that “this is almost certainly due to the superior stiffness of the expanded slate aggregate compared to many other commercially available lightweight aggregates.” The table on the next slide summarizes the test results.