Recycling of rubber waste in sand concrete

The large development in the consumption of rubber is observed in the recent years, which leads to an increase of the production of rubber related waste. Rubbers are not hazardous waste, but they constitute a hazard for both environment and health, in case of fire in storage sites. So, recycling appears as one of the best solutions for disposing of rubber waste.This paper presents an experimental investigation dealing with the valorisation of rubber waste, specifically rubber obtained from old shoes sole waste. The waste rubbers are used form (0/5 mm) to mixes as addition at percentage (10%, 20%, 30% and 40%) in sand concrete. The physical (workability, bulk density), mechanical (compressive and flexural strength) and thermal properties are studied and analysed.The results indicate that the incorporation of rubber waste particles in sand concrete contributes to increase the workability and reduce the bulk density of all studied sand concrete. The obtained results show that mechanical performance (compressive and flexural strength) decreases when the rubber content increases. Nevertheless, the presence of rubber aggregate leads to a significant reduction in thermal conductivity, which improves the thermal insulation performances of sand concrete. This study insures that reusing of recycled rubber waste in sand concrete gives a positive approach to reduce the cost of materials and solve some environmental problems

Interféromètre de type Mach-Zehnder en silicium poreux : application aux biocapteurs

International audienceDans cette étude est présentée la réalisation et la caractérisation d'un guide d'ondes optique enterré et anti-résonant à base de silicium poreux. Ce guide d'ondes est intégré dans une structure interférométrique de type Mach-Zehnder qui sera utilisée pour une application de biodétection. Les simulations et les caractérisations optiques montrent clairement le guidage monomode ainsi que le caractère anti-résonant des guides d'ondes enterrés

Functionalization control of porous silicon optical structures using reflectance spectra modeling for biosensing applications

International audienceModeling and experimental reflectance spectra of porous silicon single layers at different steps of functionalization and protein grafting process are adjusted in order to determine the volume fraction of the biomolecules attached to the internal pore surface. This method is applied in order to control the efficiency of the chemical functionalization process of porous silicon single layers. Using results from single porous silicon layer study, theoretical microcavity is simulated at each step of the functionalization process. The calculated reflectance spectrum is in good agreement to the experimental one. Therefore the single layers study can be applied to multilayer structures and can be adapted for other optical structures such as waveguides, interferometers for biosensing applications

Mechanical Response of Thin Composite Beams Made of Functionally Graded Material Using Finite Element Method

Functionally Graded Material (FGM) is a new generation of composite materials, it can be used for different engineering fields according to the loading environment, but the study of its mechanical behavior requires sophisticated numerical and analytical models. Several investigations in these models are available in the literature, however, most of those investigations are based on simplifying assumptions. In this paper, we present a three-dimensional finite element modeling of functionally graded material (FGM) beams subjected to static loading. Material properties are assumed to vary continuously along the beam thickness according to the power-law distribution with linear elastic behavior. The FGM beams are discretized by hexahedral finite elements type C3D20R (continuum stress/displacement, three-dimensional 20-node, reduced integration). We studied several numerical examples of FGM beams and compare the obtained numerical results with those of analytical models in the literature

Analysis of FGM Cantilever Beams under Bending-torsional Behavior Using a Refined 1D Beam Theory

The static bending-torsion problem of functionally graded cantilever beams is studied using a refined 1D/3D beam theory (Refined beam theory RBT and Refined beam theory with distortion modes RBT*) built on the 3D Saint-Venant (SV) solution. In these theories, the displacement models include Poisson's effects, out-of-plane deformations and distortions. For a given section, the sectional displacement modes are derived from the computation of the particular 3D Saint-Venant’s solution. These modes, which reflect the mechanical behavior of the cross-section, lead to a beam theory that actually corresponds to the cross-section type in terms of shape and material. In addition, the models take into account edge effects to predict a 3D solution in a larger internal region to better describe the overall behavior of FGM beams. The models examined are implemented on the CSB (Cross-Section and Beam Analysis) tool. It is based on the RBT/SV (Refined Beam Theory based on the 3D SV’s solution) theory of FGM beams. The mechanical and physical characteristics of the FGM beams vary continuously, according to a power-law distribution, through the thickness of the beams. The numerical and 3D results obtained with homogeneous and FGM beams are systematically compared with other models in the literature and those provided by the full Saint-Venant beam theory (SVBT) calculations

Buried Anti Resonant Reflecting Optical Waveguide based on porous silicon material for an integrated Mach Zehnder structure

International audienceA buried Anti Resonant Reflecting Optical Waveguide for an integrated Mach Zehnder structure based on porous silicon material is achieved using a classical photolithography process. Three distinct porous silicon layers are then elaborated in a single step, by varying the porosity (thus the refractive index) and the thickness while respecting the anti-resonance conditions. Simulations and experimental results clearly show the antiresonant character of the buried waveguides. Significant variation of the reflectance and light propagation with different behavior depending on the polarization and the Mach Zehnder dimensions is obtained. Finally, we confirm the feasibility of this structure for sensing applications

Towards a biosensor based on Anti Resonant Reflecting Optical Waveguide fabricated from porous silicon.

International audienceRecently, we demonstrated that Anti Resonant Reflecting Optical Waveguide (ARROW) based on porous silicon (PS) material can be used as a transducer for the development of a new optical biosensor. Compared to a conventional biosensor waveguide based on evanescent waves, the ARROW structure is designed to allow a better overlap between the propagated optical field and the molecules infiltrated in the porous core layer and so to provide better molecular interactions sensitivity. The aim of this work is to investigate the operating mode of an optical biosensor using the ARROW structure. We reported here an extensive study where the antiresonance conditions were adjusted just before the grafting of the studied molecules for a given refractive index range. The interesting feature of the studied ARROW structure is that it is elaborated from the same material which is the porous silicon obtained via a single electrochemical anodization process. After oxidation and preparation of the inner surface of porous silicon by a chemical functionalization process, bovine serum albumin (BSA) molecules, were attached essentially in the upper layer. Simulation study indicates that the proposed sensor works at the refractive index values ranging from 1.3560 to 1.3655. The experimental optical detection of the biomolecules was obtained through the modification of the propagated optical field and losses. The results indicated that the optical attenuation decreases after biomolecules attachment, corresponding to a refractive index change Δnc of the core. This reduction was of about 2 dB/cm and 3 dB/cm for Transverse Electric (TE) and Transverse Magnetic (TM) polarizations respectively. Moreover, at the detection step, the optical field was almost located inside the core layer. This result was in good agreement with the simulated near field profiles

The Effect of Ceramic Wastes on Physical and Mechanical Properties of Eco-Friendly Flowable Sand Concrete

This work aims to study the valorization and recycling of ceramic wastes (wall tiles) as a fine aggregate instead of sand in the manufacturing of flowable sand concrete (FSC). For this, the sand is substituted with the ceramic wastes at different dosages (0, 5, 10, 15, 20, and 25% by volume of the sand). The influence of the ceramic wastes addition on the physical (workability, density) and mechanical (compressive, flexural and elastic modulus) properties of FSC was studied. The results show that the use of ceramic waste as partial replacement of sand contributes to reduce the workability, bulk density and improves the mechanical strengths of FSC according to the use of 25% of wall tiles waste