Mechanical behaviour of bimodal kaolin clay with aggregates

Soil structure has been recognised as a key feature in the understanding of soil's mechanical behaviour, and research efforts have been made trying to relate them. However, the main difficulties encountered are that numerous factors can simultaneously affect the mechanical behaviour of soils. Among these factors, the presence of aggregates is decisive for the fabric configuration of bimodal soils. The aim of this paper is to evaluate the effect of aggregates on the mechanical behaviour of bimodal soils with no mineralogical variability. For this purpose, aggregates of Kaolin Clay were obtained by compaction at high stresses and bimodal samples with different aggregates content were produced. All samples were subjected to unidimensional consolidation and direct shear tests. Results showed that the increase in aggregates content and the presence of macro-pores affected compressibility, decreasing pre-consolidation stresses and altering compressibility coefficients. The increase in interaction between aggregates generated an increase in friction angles in samples with aggregates, which also impacted their volumetric behaviour during shearing. Thus, the present work contributes to a better understanding of the mechanical behaviour of bimodal soils influenced exclusively by the presence of aggregates.