Microstructural interpretation of compression behaviour of compacted kaolin clay

Clay particle aggregation controls the mechanical behaviour of clayey soils. An aggregated structure is generally associated with a bi-modal pore size distribution (e.g. soils compacted dry of optimum or at optimum water content) whereas a non-aggregated structure is generally associated with a mono-modal pore-size distribution (laboratory-reconstituted and natural sedimentary soils). Aggregation occurs as consequence of interaction of particles or clusters of particles. At this level electro-chemical forces may play an important role by i) controlling the interaction between aggregates and ii) the size and nature of the aggregates themselves in soils under both saturated and unsaturated conditions. A deeper understanding of the mechanisms and the factors controlling aggregation is therefore fundamental to predict and/or "engineer" the mechanical behaviour of clay. The paper presents a microstructural interpretation of compression behaviour of compacted kaolin clay.