Stability of fresh lightweight aggregate concrete under vibration

Abstract

The effects of rheological parameters and density differences between lightweight coarse aggregates (LWA) and mortar matrix on the stability of fresh lightweight aggregate concrete (LWAC) under vibration were studied. The stability of fresh concrete decreased with its yield stress or plastic viscosity. Tests using LWA of three different densities showed that a LWAC with a smaller density difference between the LWA and mortar matrix had better stability. Air entrainment in concrete reduced the density difference between a given LWA and the mortar matrix, and also reduced the plastic viscosity and the LWA content for a fixed material proportion. The former tends to increase stability, and the latter tends to reduce stability. The results showed that the stability of concrete was reduced with an increase in entrained air content. This indicated that the latter had a more significant effect on the stability of concrete. Copyright © 2005, American Concrete Institute. All rights reserved.