Effect of particle morphological parameters on sand grains packing properties and rheology of model mortars

• We measure aspect ratio, circularity and convexity of various sands using image analysis.
• We measure the packing properties of the various sands.
• We use magnetic resonance imaging to assess the rheological behavior of suspensions of sands in a model yield stress fluid.
• We analyze the correlations between elongation, circularity, convexity, packing and rheological properties.
• We show that variations in yield stress and in viscosity with volume fraction are correlated.

In this paper, we study the rheological behavior of mixtures of various sand particles suspended in model laboratory yield stress fluids. Using image analysis, we assess the morphology of the studied sand particles. We then measure the packing properties of these particles and show that, as a first approximation, the overall shape of the particles (i.e. the aspect ratio) is the dominant morphological parameter conditioning packing. We finally use magnetic resonance imaging (MRI) to assess the rheological behavior of suspensions of these sands in a water-in-oil emulsion and show that both the yield stress and consistency diverge for the same critical volume fraction, which seems to be fully correlated to both the random dense packing fraction and loose packing fraction of the grains. We finally suggest that there exists a correlation between a variation in yield stress and a variation in viscosity due to a change in the particle morphology.