In this talk, we report experimental data on shear stress-controlled rheology of concentrated aqueous suspensions of isometric (polyhedral shaped) calcium carbonate (CaCO3) microparticles with an adsorbed comb polymer layer (polymethacrylate backbone with side polyethylene oxide chains) with and without addition of uncoated micron-sized polyamide fibers. Independently of the presence of fibers, the suspensions undergo a discontinuous shear thickening (DST) at the CaCO3 particle volume fraction above 64% (the particle size distribution being polydisperse) and exhibit a stick-slip instability above some critical shear stress likely because of periodic collapse and restitution of the adsorbed polymer layer leading to periodic formation and failure of percolated network of frictional interparticle contacts. Addition of long (aspect ratio r=50) and relatively AERC Abstract Update-View Paper https://www.rheology.org/aercabst/ViewPaper.aspx 1 sur 2 12/11/2018 à 13:52