Fabrice Toussaint

Holcim · Concrete & Aggregates

During cement hydration, solid, fluid, and total volumes vary as water is consumed by chemical reactions. Those volume variations lead to pore water pressure decrease during the first hours of hydration. The deformations induced by early hydration are quantified in order to understand their consequences on the internal stress state within the harde...

In a slipforming process, concrete is continuously poured and the formwork simultaneously raised so that the older concrete on the bottom supports the fresher on the top after a few hours of hydration. The objective of the present study is to examine the evolution of the concrete/formwork interface at very early age. An experimental device was desi...

For concrete and other cement-based materials, cement hydration induces Le Chatelier contraction. This phenomenon creates negative pore water pressure, which increases the bulk and interfacial granular stresses and affects both the interfacial and bulk rheological behavior of the dense mineral suspension. An original device was developed to assess...

In a slipforming process, concrete is continuously poured and the formwork simultaneously raised so that the older concrete at the bottom supports the fresher at the top after a few hours of hydration. Such a complex process has to be industrially optimized to ensure the quality surface of concrete. The objective of the present work is to study the...

This study focus on the early age properties of two mortar formulations designed for a 3D printing extrusion process. They follow a new design and process strategy, which consists in formulating a mortar to be self-levelling, to optimize pumpability, and then incorporating an additive in the extrusion nozzle to modify rheology properties and settin...

We experimentally study the behavior of suspensions of silica particles in aqueous solution. Despite many studies on these materials, the dependence of the overall rheological properties of the suspension on particle size, solid volume fraction, ionic strength, and strain history remains debated. In this paper, we manage to manufacture materials an...

The objective of this study was to test the capability of numerical tools to predict the orientation of fibres in various configurations of casting Ductal ®. A strong industrial challenge is to find the best casting configuration of very big windmill elements. Fourdifferent configurations were experimentally casted and tested in a reduced scale. Ma...

Measurement artifacts in concrete or mortar rheometers often prevent the user from having access to absolute correct values of the rheological parameters of the tested material. As there does not exist any rheometer giving access to the “correct” or “real” values of these parameters, it is even not possible to estimate the order of magnitude of the...

Rheological measurements were made on concrete and mortars to characterize the shear thickening behavior of certain concrete mix designs. Shear thickening reduction levers were found by selecting and designing admixtures. Since the shear-thickening phenomena occur at the scale of the finest particles, industrial limestone fillers were studied that...

Disordered assemblies with maximum packing fraction are studied by discrete element numerical simulation for monodisperse or bidisperse spherical particles, the diameter ratio being set at three. A maximum packing fraction value corresponds to an equilibrium state under isotropic loading of rigid frictionless particles. A statistical study of size...

Ce travail propose une approche multi-domaine pour modéliser l'écoulement d'un fluide complexe (un fluide de Bingham). Une attention plus particulière est portée à l'interface liquide-air et à l'orientation des fibres. Les applications concernent l'ajout de tiges de métal au béton liquide afin d'améliorer les propriétés mécaniques des poutrelles. L...

Disordered assemblies with maximum packing fraction are studied by discrete element numerical simulation for monodisperse or bidisperse spherical particles, the diameter ratio being set at three. A maximum packing fraction value corresponds to an equilibrium state under isotropic loading of rigid frictionless particles. A statistical study of size...

The aim of this paper is to propose a multi‐domain approach to model the flow motion of concrete flow. We mainly deal with free surfaces, material interfaces and fiber orientation. The main application behind this paper is related with the addition of rigid long metal pieces to fresh concrete in order to improve the final mechanical properties of c...

The aim of this paper is to propose a multi-domain approach to model the flow motion of concrete flow. We mainly deal with free surfaces, material interfaces and fiber orientation. The main application behind this paper is related with the addition of rigid long metal pieces to fresh concrete in order to improve the final mechanical properties of c...

In the present work, the effects of pressure on the viscosity and flow stability of four commercial grade polyethylenes (PEs) have been studied: linear-low-density polyethylene copolymer, high-density polyethylene, metallocene polyethylenes with short-chain branches (mPE-SCB), and metallocene polyethylenes with long chain branching (mPE-LCB). The r...

During the extrusion of polymers the extrudate leaving the die is smooth and transparent when the flow rate is low enough, and may be very swollen. As the flow regime progressively increases, and irrespective of the polymer used in this study, scratches, i.e. small amplitude local cracks, appear on the surface of the extrudate, situated in longitud...

An overview is given of extrudate distortions, flow fields and flow curves observed for flexible polymer melts, when they are extruded using axisymmetric or two-dimensional dies. Die walls with high surface energy and low-energy slippery surfaces are considered, as well as the influence of wall roughness. The connection between flow curves and th...