Contribution for the structural characterization of the particles of light weight expanded clay aggregates

Abstract

The use of light weight expanded clay aggregates to built road embankments is nowadays a common practice mainly when very soft soil foundations are present. There are good reasons to think that the knowledge of the nature of the structure of the material is an important contribution to the establishment of appropriate constitutive relationships. These relationships are necessary to settlement evaluation that may have a negative impact on road performance during exploration. Another practical aspect is concerned with the construction techniques to be used. This study is inserted in a more general research carried out by the Laboratório Nacional de Engenharia Civil and the Instituto Superior Técnico, funded by Saint Gobain, concerning the mechanical behaviour of embankments of this manufactured material. The study presented was focused on better understanding the material structure and the role of suction (of the water, in a more broad sense) on the embankment mechanical behaviour. Laboratorial tests were performed including oedometric tests in aggregates for the cases dry and submerged. Crushing strength for different water contents and the water retention curves of single particles of light weight expanded clay composing the aggregate were also measured. The results found in the study of the aggregate were related, when possible, with the results found for the particle. In a first analysis, it was found that the particles are almost insensitive to water. Nevertheless, the crushing strength of the particles seams to depend on their water content. The aim of this work is to clarify this matter through a deeper experimental investigation.