Joseph J. Biernacki

Tennessee Tech University

Particle Size Distribution Models

It is unanimously agreed upon by researchers working on cement hydration that the cement particle size distribution (PSD) must be accounted for when predicting dynamice hydration behavior.  This page illustrates one simple way to incoporate particle size disbribution into a kinetic model and outlines the assumptions implied.  Models utilizing particle distribution are also posted here to illustrate the practice.

Particle distribution applet: UNDER CONSTRUCTION

Knudsen applet: Likely the most well known model that incoporates particle size distribution is that of Knudsen.  Frequently referred to as “Knudsen’s Disperions Equation” there term “dispersion” referres the the distribution (dispersion) in partile size.  While the model is elegant, it ustilizes heuristic forms for the chemical kinetics and size distribution.  Nonetheless, it has been widely applied and cited in the cement’s hydration literature.

Pommersheim with PSD applet: After developing his mass continuity-based reaction-diffusion model, Pommersheim implemented Knudsen’s integral appraoch to include a particle size distribution.  This applet includes the option to add a particle size distribution to our baselline Pommersheim applet.

Bishnoi with PSD applet: Bishnoi and Scrivener’s single particle model is embeded within a simulation environment called mic which permits the modeling of thousands of particle simultaneously.  Here we use a simler apprach wherein we include a particle size distribution by applying Knudsen’s integral method.  This approach does not permit the explicit calculation of particle-to-particle interactions as is done using mic, but does illustrate the effect that a distribution of particle sizes has on this model.

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