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Approche couplée expérimentation – modélisation multi-échelle pour la détermination du comportement mécanique des graves routières traitées aux liants. Application à la valorisation des Mâchefers d’Incinération de Déchets Non Dangereux.

In this work, the feasibility of a valorisation in road engineering of non-hazardous waste incineration bottom ash aggregates (NHWI) is investigated. This study is first based on an experimental determination of the elastic properties of the bottom ash particles. These properties serve as input data for a hierarchical multi-scale modelling developed to study the mechanical behaviour of aggregates treated with binders (cement and bitumen). The original experimental campaign on the bottom ash particles allowed them to be mapped to the Scanning Electron Microscope (SEM). For these particles, a mean reduced modulus of elasticity in between 15 and 68 GPa was found by means of indentation tests and applying the "Olivier and Pharr" method. The chemical analysis of the aggregates was obtained using qualitative point chemical analyzes (DHS). Based on a 0/25 particle size distribution of NHWI, which was the subject of an experimental study (Becquart F., 2007), we have implemented two 3D models of road materials treated with binders in Representative Elementary Volumes (REV). These models are based on a hierarchical multi-scale modelling strategy. Two types of binder are studied: cement CEM I 42.5 R and bitumen of (Nguyen H.N., 2008). For both types of binder, the treated aggregates were divided into two REV, at respectively the sub-mesoscale (0/6 mm) and the mesoscale (6/25 mm). An application to the valorisation of NHWI bottom ashes in road engineering is studied in both cases. With a 3% cement treatment, a numerical simulation campaign "Virtual Laboratory" was conducted. At the sub-mesoscale, the input parameters for the Concrete Damaged Plasticity Model used at the mesoscale are determined. At the mesoscale, the mechanical characteristics of the road materials usually determined through experiments have been found. The developed simulation strategy has been validated by comparing our numerical results and some experimental results of (Becquart F., 2007). With a 5% bitumen treatment, stress relaxation tests carried out at the two scales enable one to obtain the thermo-rheological properties of the Bitumen-Bound Gravel. These properties are the Prony series at a reference temperature of 0 °C and the Williams–Landel–Ferry (WLF) law constants. Prony series are obtained by means of standardized elastic moduli. The obtained WLF law constants are C1 = 20 °C-1 and C2 = 130 °C. The numerical simulations have been validated by comparing the responses of heterogeneous and corresponding homogeneous materials.

Auteur(s) : Libasse SOW
Année de publication : 2018
Revue :
Type : These
Mise en ligne par : SOW Libasse