Rheological characterisation of cold bitumen emulsion slurries

The performance of cold bitumen emulsion (CBE) mixtures is strongly linked to an optimised design of the binder blends and mastics. Types and dosages of bitumen, mineral additions and the workability must be characterised and optimised. This study aims at providing an approach for the fundamental characterisation of CBE materials using rotational viscometry. Firstly, a procedure for measuring the viscosity of CBE slurries using the Brookfield viscometer was investigated by comparing results obtained by using a traditional spindle geometry and a novel impeller engineered to avoid phase separation: the dual helical ribbon (DHR). Afterwards, the effect of mineral additions and bitumen emulsions types was measured and modelled, also considering the influence of their concentration. The Krieger-Dougherty model proved to be a powerful tool to fit results and provide fundamental parameters for improved CBE materials engineering characterisation. Overall, the DHR was found a promising tool for CBE slurries rheological characterisation.