Fig. 3: Material parameters that non-dimensionalize flow curves.

The different colors correspond to the respective relative clay fraction ξ: 0.2 (red), 0.4 (violet), 0.6 (blue), 0.8 (peach), and 1.0 (green). For better visualization of the trends, data are classified into three distinct types: sand-rich (lower triangles; ξ = 0.20 and ξ = 0.40), clay-rich (upper triangles; ξ = 0.8 and ξ = 1.0), and intermediate (ξ = 0.6). a Variation in fit values of the yield stress τ_y with increasing volume fraction ϕ, for various values of ξ. Trend lines for each ξ are shown to guide the eye. The sand-rich mixtures (red and violet) follow a steady trend of increasing τ_y with increasing ϕ, as reported in the literature^14,42. Clay-rich mixtures show a drop off in yield stress below a critical value ϕ_c, and a critical scaling of the form \({\tau }_{{\rm {y}}} \sim {({\phi }_{{\rm {c}}}-\phi )}^{k}\), which is associated with the minimal kaolin gel network required to bear the shear stress^41,42. b The change in microscopic rearrangement time (t_μ) with increasing ϕ across ξ values. The dark stars indicate the ϕ values (jamming distance, ϕ_m−ϕ = 0.03) chosen to perform transient rheology in Fig. 4b. Timescale decreases monotonically with increasing ϕ for clay-rich suspensions, but plateaus at a constant value for sand-rich suspensions. c Empirically determined microscopic timescale (t_μ), used to collapse the curves in Fig. 2f, scales with the estimated rearrangement timescale of a yield stress fluid (η(Δϕ)/τ_y). Source data are provided as a Source Data file.