Papers by Author: Martijn Stroeven

Abstract: Fresh model cement mixtures, with the same w/c ratio and particle size distribution, were simulated by the SPACE system that is based on a dynamic mixing algorithm. Thereupon, they were hydrated by the HYMOSTRUC 3D system. Boundary conditions were varied, rendering possible assessment of their influence on percolation of capillary porosity by serial sectioning and using the overlap of slices. Simulation results revealed increases in total porosity and in connected fraction of capillary pores due to the existence of aggregate. The de-percolation threshold of capillary porosity was found not only related to total porosity and image resolution, but also governed by the spatial distribution of capillary pores.

Abstract: The computer simulation study of Portland cement blending confirmed the major mechanism to be size segregation in the Interfacial Transition Zones around the aggregate particles. Fine particles tend to move through the skeleton of larger particles towards the surface of the aggregate grains, improving local density. But the most interesting feature is a disproportionately larger internal bond capacity (based on van der Waals forces between nearby particles). In this contribution, we have isolated the mechanism of internal diffusion capacity of particles, on which blending efficiency relies, for a simulation study on the migration of fine sand articles into the network of coarse aggregate grains. The influences of technical parameters (including gap in size between fine sand and coarse aggregate, as well as the workability conditions) have been investigated on the migration capacity of fine sand particles. This paper will report briefly the outcomes of this computer simulation study on aggregate mix systems.