Infiltration of cement paste in porous media

Abstract

The aim of this study is to analyse the infiltration of a cement paste into a pack of expanded clay beads (Leca). In preliminary experiments, we focused on experimental difficulties such as the wall effect (the packing of beads is naturally lower at the boundaries of the container), the evolution of the behaviour of the slurry containing superplasticizer with time, and the porosity of the Leca beads and their absorption of water. The porosity of the Leca beads can indeed make the infiltration process more challenging, as dry beads may tend to absorb water from the cement slurry, producing a filtration process that could lead to plugging and prevent further penetration of the slurry, similar to issues happening during grouting.Two infiltration setups were designed and built during the course of this master thesis: an infiltration setup using gravity (cement poured from top) and an infiltration setup using a pumpinjecting cement slurry from the bottom. Parameters investigated include the Leca bead size,their saturation with water and the rheological properties of the cement slurry. During the experiments, the infiltration time versus pressure and the change of the properties of the slurry due to the infiltration process were measured. The goal is to provide an understanding of the required properties of a cement paste sought to infiltrate into a porous media.