Mesostructure of Foamed Cement Paste and Its Influence on Macromechanical Behavior

Abstract

Foamed cement paste has been used increasingly as a backfill material in geotechnical engineering applications, such as embankments, tunnels, and retaining walls. However, limited studies have focused on the influence of void structures of the foamed cement paste on its macromechanical behavior. This study used X-ray computed tomography (X-CT) to investigate the void structures of foamed cement paste and their influence on the macromechanical properties (strength and modulus). The test results showed that the void volumes had a unimodal distribution. The reduction in the density of the specimen indicated more large voids and a wider distribution of void sizes; however, surrounded-type voids were dominant in terms of percentage of total volume. The sphericity of the voids ranged from 0.1 to 0.6, indicating their highly irregular shapes. Sensitivity analysis showed that the volume of the surrounded-type voids played a primary role in the compressive behavior of the foamed cement paste, the void shape was the secondary influence factor, and the void size was the tertiary influence factor.