Study of the structure of a sensitive Champlain clay and of its evolution during consolidation

TLDR

Scanning electron microscopy and mercury intrusion porosimetry were applied in parallel to characterize the microstructure of medium‑sensitivity Champlain clay across intact, remolded, oven‑dried, and progressively one‑dimensional compressed samples. The combined techniques revealed an aggregated structure with distinct inter‑ and intra‑aggregate porosity, showed that remolding alters inter‑aggregate links while preserving aggregates, and demonstrated a progressive collapse of the structure during compression—largest pores collapse first, smaller pores later, with anisotropy developing as compression increases. Keywords: natural clay, microstructure, freeze‑drying, porosimetry, microscopy, consolidation, aggregate.

Abstract

Scanning electron microscopy and mercury intrusion porosimetry are used in parallel to identify the structure of a medium sensitivity Champlain clay. The clay structure is observed firstly on intact, remolded, and oven-dried soils and secondly on soils consolidated at various levels in one-dimensional compression. Both methods of investigation reveal for the intact soil the existence of an aggregated structure characterized by an interaggregate and an intra-aggregate porosity. Remolding affects interaggregate links but does not destroy aggregates.The observation of clay structure at various levels of one-dimensional compression shows that the collapse of the structure is progressive, the largest interaggregate pores being the first affected. As the consolidation proceeds, smaller and smaller pores are affected. For a given pressure increment, only the largest existing pores are affected. A structure anisotropy has been seen to develop with increasing compression.The scanning electron microscope and the mercury intrusion porosimeter used in conjunction with each other appear as a powerful approach for clay structure observation. Keywords: natural clay, microstructure, freeze-drying, porosimetry, microscopy, consolidation, aggregate.