Movement of air voids in lightweight concrete mixtures during vibration compaction

The article investigates the process of vibrational compaction of polystyrene concrete mixture under the influence of combined harmonic excitation. The relevance of the study is due to the need to improve the structural uniformity and reduce the porosity of lightweight concrete products by optimizing compaction regimes. The study addresses the specific problem of inefficient air inclusion removal in mixtures with a high content of deformable polystyrene aggregates. The aim is to develop a dynamic model of the "platform – concrete mixture – mold" system and to determine optimal vibration parameters that ensure effective expulsion of air bubbles. The research methodology includes analytical modeling of dynamic pressure fields, numerical estimation of air bubble drift velocity using modified Stokes law, and evaluation of pressure gradients during vertical, horizontal, and combined excitation modes. The results demonstrate that combined excitation significantly enhances the upward migration of air inclusions due to spiral drift and pressure wave interaction. The highest compaction efficiency is achieved near the resonance frequency of the system. The findings can be applied to improve the technological parameters of vibrational compaction in the production of polystyrene concrete elements.