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Clay soils consist of fine particles and are generally characterized by low strength. The interactions between clays and water result in high-plasticity clay mixtures that can easily deform or crack. It should be noted that the addition of sand to expansive soils can help to improve their particle size and reduce their plasticity, and consequently augment their strength. The present study aims mainly to develop a model for the prediction of the plasticity index (PI) of soil treated with sand, at various contents using the artificial neural network (ANN) method. It was revealed that the ANN technique ensures good prediction accuracy for a large number of parameters related to geotechnical problems. For the purpose of predicting the plasticity index values of sand-treated soils, the results of experimental tests that were conducted on 38 soil samples were collected and thoroughly analyzed. It was decided to consider three inputs, namely the plastic limit, liquid limit, and sand percentage, while there was only one output, i.e. the plasticity index. The results of the analyses conducted in this study indicated that the artificial neural network (ANN) model might be quite efficient in predicting the plasticity index of soils treated with sand. Afterwards, an experimental investigation was carried out on the clayey soil that was brought from the Wilaya (Province) of Medea in Algeria. This soil was treated with dune sand at different percentages, and the results obtained were compared with those predicted by the artificial neural network (ANN) technique.

This work, which is part of the FIBRABETON project, aims to anti-fissuration screed formulations proposition based on natural fibers and comparing these formulations to a synthetic fiber-screed formulation. Different natural fiber (hemp, flax, miscanthus and bamboo) with contents rangingfrom 0.4% to 0.8% were tested. The spread (slump), the shrinkage and mechanical strength (flexural and compressive) studies were carried out. SEM images of natural fibers and natural fibers screed formulation were analyzed. Overall, it is found that all natural fibers screed formulations tested, have shown better behaviour than the synthetic fibers screed formulation in point of view workability, shrinkage and mechanical properties. The lowest shrinkage value is found in the case of the H5 (5 mm long hemp fibers) screed formulation. Generally speaking, the mechanical strength values (flexural and compressive) are more or less similar between natural soft fibers (hemp and flax) and rigid fibers (miscanthus and bamboo). Taking in account slump, shrinkage and mechanical behavior, the proposed good compromise in this work is the H5 screed formulation.

This paper focuses on the effectiveness in the improvement of clay soils of using geopolymers of fly ash (FA), metakaolin (MK), or blast furnace slag, activated by an alkaline solution of ...

Clayey soils are considered as problematic soils for geotechnical engineering . They are characterized by poor geotechnical properties because of their high plasticity and water absorption properties. The consisting treatment by substituting a fraction of these soils by an inert sand is approached. However, if some conclusions are common to these works, they could not be generalized. Very often, the results obtained depend on the nature and intrinsic properties of the soils considered. The aim of the present study is to investigate clayey soil (from the region of Medea, Algeria) treatment effect by using dune sand on geotechnical, structural and mineralogical properties. Atterberg limits , compaction and unconfined compression tests are performed on clay soil and for mixtures with different dune sand percentages. In addition, triaxial tests and free swelling oedometric tests are carried out on the mixture corresponding to the optimal dune sand content. The mineralogical properties are determined using X-ray diffraction (XRD). X-ray diffraction patterns have showed that the dune sand addition in clay soil introduces only a change in quartz intensity. In addition, it is observed that the treatment provides a substantial improvement in the mechanical properties, especially for the 30% dune sand mixture. Nevertheless, this optimal with 30% dune sand mixture does not solve the problem of swelling, because the latter is important than untreated clay soil.

Recycled concrete aggregates (RCA) originated from old deconstructed concrete may contain considerable amounts of heavy metals like chromium for example. In this work, we study the presence of chromium impact in the cementitious matrix of RCA, cement doped paste (OPC) and mortar with RCA (30% and 100% of RCA) from an environmental point of view. The leaching tests are carried out on monolithic and granular samples, using carbonated and non-carbonated RCA. Cr (VI) pH dependent leaching and Cr (VI) leaching mechanism have been studied. The experimental results has shown that aggregates are inert waste and can be used for road construction as substitution of original aggregates. Moreover, carbonation seems to have a positive effect on the decrease of the release of hexavalent chromium from the cementitious matrix. It was also confirmed that chromium is highly bound in the ettringite structure still present in the RCA matrix.

The aim of this work is to study the heat treatment effect, milling time effect and indirect mechanosynthesis effect on the structure of the mixture limestone/clay (kaolinite). Indirect mechanosynthesis is a process that combines between mechanical activation and heat treatment at 900 &deg, C. XRD, TGA, FTIR and particle size distribution analysis and SEM micrograph are used in order to follow thermal properties and structural modification changes that occur. It is shown that the indirect mechanosynthesis process allows the formation of the equivalent clinker in powder with the main constituents of the clinker (Alite C3S, belite C2S, tricalcium aluminate C3A and tetracalcium aluminoferrite C4AF) at 900 &deg, C, whereas, these constituents in the conventional clinker are obtained at 1450 &deg, C.

This study investigates the durability of fly ash-based geopolymer pastes (FA-GP). Thermal behavior was evaluated by heating the FA-GP pastes at 1000 °C for 2 h (FA-GP-1000 °C). Acid resistance was studied by immersing specimens in a 5% sulfuric acid solution for a period of 4 months (FA-GP-H2SO4). Physicochemical, microstructural and mechanical changes after heat and acid exposure were studied using several analysis methods such as Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM) and compressive strength. The results showed that the visual appearance of fly ash-based geopolymer samples was well preserved after high temperature exposure, and kept about 37% of its initial compressive strength value. SEM micrographs of acid exposed samples showed very porous structure with some micro-cracks, inducing a decrease of the residual compressive strength of about 33.33 %.

This work aims to study the feasibility of preparation of geopolymer pastes, from pre-geopolymer powders obtained by mechanosynthesis and water. These geopolymer pastes (MGP) were compared to the conventional geopolymer pastes (CGP) in terms of structural, microstructural and mechanical properties. CGP were manufactured by the mixture of fly ash as precursor with alkaline activator solution. Pre-geopolymer powders (PGP) were prepared by the high-energy milling of a dry mixture of fly ash and alkaline activators, with different Na2SiO3/NaOH mass ratios (2.5, 4 and 8) and milling times of 5, 10 and 15 min. CGP and MGP pastes were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), particle size distribution analysis, compressive strength tests and in situ attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), in order to highlight structural, microstructural and mechanical changes that could occur, and to follow geopolymerization kinetics respectively. The results pointed out that the MGP structures are mainly amorphous, with appearance of zeolitic crystals, depending of the chosen formula and the milling time. The in situ ATR-FTIR analysis indicated that the fly ash characteristic band (1027 cm−1) shifts towards lower wavenumbers, with a much larger shift for MGP than for CGP. The compressive strength results showed optimum values of 28 MPa for MGP and 15 MPa for CGP, after 7 curing days at 20 °C and 50% of relative humidity.

The effect of the substitution by 5%, 15%, 30% and 45% of cement in mortars by milled kaolinite has been studied. Milled Kaolinite clay is obtained by using planetary ball mill. The influence on the mechanical performance and on the pozzolanic reactions are discussed. For both CEM I and CEM II formulations, after only 7 days of curing, the compression strength of mortars with 5% of milled kaolinite is comparable to the one of reference mortars for milling times of 3 h and above. For CEM I mortar, the results of the compressive strength show that 15% of kaolinite milled for 9 h allows the best compressive gain for 28 curing days and 90 curing days with 18.5% and 25.6%, respectively. For CEM II mortar, 15% of kaolinite milled for 9 h exhibits the best values of compressive gain for 28 curing days and 90 curing days with 9.8% and 9.7% respectively.

In this study, we have modified slag and fly ashes by mechanosynthesis process carried out by high-energy ball milling using a planetary mill. In order to optimize the milling conditions, we have added process control agent (PCA). This PCA affects powders agglomeration phenomena during milling and impacts the milling time for the final product. We have studied the structure and microstructure of coproducts (fly ashes and slag) obtained by mechanical activation. In addition, we have also tested the mechanical performances of samples prepared with the addition of activated coproducts.

Planetary ball mill is used to process kaolinite clay powder under a commercial name of proclay kaolinite. Influence of milling time on structure and thermal behavior of proclay kaolinite are presented and discussed. X-ray powder diffraction shows that peak intensities, at kaolinite characteristic positions, decrease gradually and decay after 3 hours of milling. Amorphous structure of kaolinite forms with a nanocrystalline quartz. The mean crystallite size of nanocrystalline quartz is found to decrease from D = 30 ± 2 nm for unmilled powder to D = 7 ± 1.5 nm after 9 hours of processing. For the same time shift, thermal analysis shows that specific heat capacity of unmilled powder increases from 0.93 J/g.K to 1.65 J/g.K for milled powder.

This work aims at bridging the efficiency of ball milling of granulated blast furnace slag (GBFS) to the structural and mechanical properties of slag cement pastes. Both conventional and high energy milling of GBFS are considered with a milling duration varied between 1 and 10 h. X-ray diffraction, infra-red spectroscopy, granulometry analysis and scanning electron microscopy are used to draw the main lines of structural and Morphological changes occurring during milling. Cement pastes formulated using 45% of GBFS in substitution are Characterized. Workability, X-ray diffraction analysis, differential scanning calorimetry and compressive testing ate performed to analyse main structural changes and reactions driven by the presence of milled GBFS as well as its direct consequence on the mechanical strength of slag cement pastes. Slag milling indicates the superior efficiency of high-energy milling, which allows a maximum slag finesse of 1.79 m(2)/g after 3 h of milling. Major structural changes occur during the first 3 h of high energy milling while conventional milling does not induce any remarkable trend. These changes concern amorphisation of the bulk structure in addition to the fracturing and agglomeration of slag particles. Workability of slag cement pastes is remarkably improved when using 1 h of high-energy slag milling. This result is consistent with slag finesse trend with respect to milling time and with the improvement of GBFS reactivity. The substitution of 45% of cement (CEM I 52.5) by GBFS is only beneficial at the condition of performing high-energy milling for at least 1 h.

Mechanical performance of modified mortar using hemp fibres is studied following various processing conditions. Hemp fibres combined with carbon nanotubes (CNT) are introduced in mortar and their effect is studied as function of curing time. The cement phase is replaced by different percentages of dry or wet hemp fibres ranging from 1.1 wt% up to 3.1 wt% whereas carbon nanotubes are dispersed in the aqueous solution. Our experimental results show that compressive and flexural strengths of wet fibres modified mortar are higher than those for dry hemp-mortar material. The achieved optimal percentage of wet hemp fibres is 2.1 wt% allowing a flexural strength higher than that of reference mortar. The addition of an optimal CNT concentration (0.01 wt%) combined with wet hemp has a reinforcing effect which turns to be related to an improvement of compressive and flexural strengths by 10% and 24%, respectively, in comparison with reference condition.

Risk studies are very important to avoid human and economic losses. However the study cost becomes very expensive in some case when the site scale is very large. That's why; using a numerical simulation with a small-scale model is considered as a suitable solution. In order to have accurate results on which we can rely to assess the risk, it is necessary to use sophisticated means to simulate with a high efficiency the study area. One of the very accurate means able to do that is based on laser scanning techniques. This article describes how a 3D laser scanning can provide quickly and accurately a 3D model of the study area reduced model for the risk simulation step. Moreover, the necessary processing steps in the laser software named Geomagic v12, are highlighted to achieve a neat 3-D model. The article also describes the preparation of the model for the numerical simulation step.

The consideration of planetary ball mill processing is attempted to obtain modified fly ashes powders that are used as substitutes in a cement paste. Ball milling conditions are related to structural modifications of processed powders. These modifications are retrieved from X-ray diffraction, infrared spectroscopy, powder granulometry, and scanning electron microscopy. As an industrial application, the milled fly ashes are substituted to two different cements to show possible effect on compressive strength of cement pastes. Structural analysis of milled fly ashes show loss of crystallinity of the magnetite phase, nanosizing trend of quartz and mullite phases with some straining that takes place after only 1 h of milling. The drop of particle size of the milled fly ashes is also evidenced but with tendency to agglomeration and particle shape modification from spherical to irregular forms.Mechanical performance results related to modified cement pastes indicate successful substitution of cements by milled fly ashes up to 50%. Substitution results in levels of compressive strength as large as 70 MPa for particular combination of milling time, fly ash content and curing time. Keywords: Ball milling, Fly ash substitution, Structural analysis, Compressive strength, Cement paste

Date palm residues capabilities in civil engineering are evaluated by combining numerical and experimental approaches. Date palm spikelet originated from Elghers variety is added to mortar as a raw material or after chemical modification. Evaluation of reinforcement effect is performed using mechanical testing. Finite element modelling is considered to predict the interfacial behaviour and mechanical performance under various structural and mechanical hypotheses. Experimental results show limited effect of untreated spikelet on mortar performance for volume reinforcement of 1%. Larger contents result in severe degradation of mechanical performance compared to reference mortar. The addition of carbon nanotubes improves slightly the performance. Chemical treatment using both NaOH and CaO results in reinforced effect of spikelet. Numerical predictions show limited load transfer across the matrix/untreated spikelet interface and large interface stiffness for those formulations including small spikelet, CNT and chemical treatment.

The substitutional doping of Mn in Mg2Ni phase and the electronic structure of Mg3MnNi2 phase have been investigated by first principles density functional theory calculations. The calculation of enthalpy of formation shows that among the four different lattice sites of Mg(6f), Mg(6i), Ni(3b) and Ni(3d) in Mg2Ni unit cell, the most preferable site of substitution of Mn in Mg2Ni lattice has been confirmed to be Mg(6i) lattice site. The constructed Mg9Mn3Mg(6i)Ni6 structure by replacing 3 Mg atoms at Mg(6i) lattice sites with 3 Mn atoms in the Mg2Ni unit cell is less stable. In contrast, the cubic Mg3MnNi2 phase that has the same composition as that of Mg9Mn3Mg(6i)Ni6 structure possesses good stability. Analysis of density of states (DOS) indicates that there is a strong hybridization between Mg s, Mg p and Ni d electrons, which is dominant in controlling the structural stability of pure and Mn-doped Mg2Ni phases. The Mn-substitution in Mg2Ni unit cell weakens the interaction between Mg s, Mg p and Ni d electrons, especially for Mg9Mn3Mg(6i)Ni6 phase. The cubic Mg3MnNi2 phase possesses a strong hybridization between Mn and Mg, Ni atomic orbits under simultaneously retaining the strong bonding among Mg s, Mg p and Ni d electrons. Based on the calculated results, the stability of phases gradually decreases along the sequence pure Mg2Ni phase > Mg3MnNi2 phase > Mn-substitution doped Mg2Ni phase.

In this paper a numerical study of urban flooding caused by dam break has been undertaken. Problem state- ment: This study illustrated the influence of the different versions of K-epsilon turbulence model on the water flow behav- ior, predicted by Computational Fluid Dynamic (CFD) and validated through experiment. Approach: The water velocity, free surface profile and also secondary circulation flow along with the pressure through the city are simulated and proved. Results: Results are obtained with numerical simulation using standard k-epsilon, are relatively good agreement with the experimental results. Conclusion/Recommendations: In the present study, the velocity and the water depth are investi- gated to check the real capabilities of a 3D numerical code ANSYS-CFX and especially to define the optimal parameters (Mesh, boundary conditions, turbulence model,) able to simulate the flow behavior through the complex urban area, with the best accuracy.

This paper is dedicated to the optimization of magnetic properties of iron based magnetic materials with regard to milling and coating process conditions using artificial neural network methodology. Fe–20 wt.% Ni and Fe–6.5 wt.% Si, alloys were obtained using two high-energy ball milling technologies, namely a planetary ball mill P4 vario ball mill from Fritsch and planetary ball mill from Retch. Further processing of Fe–Si powder allowed the spraying of the feedstock material using high-velocity oxy-fuel (HVOF) process to obtain a relatively dense coating. Input parameters were the disc Ω and vial ω speed rotations for the milling technique, and spray distance and oxygen flow rate in the case of coating process. Two main magnetic parameters are optimized namely the saturation magnetization and the coercivity. Predicted results depict clearly coupled effects of input parameters to vary magnetic parameters. In particular, the increase of saturation magnetization is correlated to the increase of the product Ωω (shock power) and the product of spray parameters. Largest coercivity values are correlated to the increase of the ratio Ω/ω (shock mode process) and the increase of the product of spray parameters.

In this study, we focus on the determination of the heat transfer properties in Tungsten-Inert-Gas welding (TIG) problem combining an experimental and a three-dimensional simulation approaches. Optimal conditions are used to weld stainless steel (304L) sheets in butt configuration. Both instrumental monitoring and metallographic investigation of the welded material are carried out. The modelling of the heat source is performed by a mobile Gaussian surface source exhibiting a bi-elliptical shape. This source is implemented in a three-dimensional finite element model to compute heat flux and temperature fields. The comparison between the experimental and numerical thermal cycles shows a fair agreement. Predicted temperature fields and heat flux distributions are discussed. Conversion of isotherms into microstructural information shows that the size of the fusion zone is four times smaller than the heat affected zone dimension. The metallographic analysis confirms the expected microstructural evolutions but highlights differences between observed and predicted extents of the heat affected zone.

In this work, we investigate the effect of hemp fibre and shive addition on modified mortars microstructure and mechanical performance. The mortar formulation is adjusted with different percentages and lengths of either hemp fibres or shives. Workability of fresh modified mortars is carried out using two main techniques including maniabilimeter and flow table experiments. Microstructural effects are revealed using X-ray μ-tomography where the pore content and 3D spatial arrangement and content of hemp are all investigated. Mechanical performance is derived from bending and compression testing at different curing times. Results show the potential of using natural fibres as substitutes leading, in this study, to improvement of mechanical strength but deterioration of stiffness. Superior mechanical performance with compression full strengths as large as 66 MPa is achieved using high-energy ball milling process of fly ashes that are added to unmodified mortar. Results show also that optimal formulations need to involve both hemp fillers and milled fly ashes. These formulations reveal superior mechanical performance compared to all tested conditions after only 7 curing days. Keywords: Hemp fibres, Hemp shives, Modified mortar, Milled fly ashes, Mechanical performance, X-ray μ-tomography

In the present work, solidification/stabilization (S/S) of nickel contaminated soil using Ordinary Portland CementOPC and commercial was carried out. Effects of different binder combinations of OPC and commercial stabilizer wt% in the S/S mix designs and physical and chemical characteristics of the treated samples were investigated. The mechanical property studied was unconfined compressive strength-UCS while chemical characterization of the samples was focused on the leachability of nickel. Results indicated that the optimum mix design, in terms of mechanical efficiency, was 10% OPC wt% and 4.2 wt% commercial stabilizer while in terms of chemical efficiency 10% OPC wt% and 1.4 wt% commercial stabilizer.

Fe–20 wt.% Ni alloys were prepared using a planetary ball mill PM 400 from Retsch (with different milling times for Ω = 400 rpm, ω = 800 rpm) and P4 vario ball mill from Fritsch (with different milling conditions ( Ω / ω ), Ω and ω being the disc and the vial rotation speeds, respectively). The bcc-Fe(Ni) phase formation is identified by X-ray diffraction. The higher the shock power and the higher milling time are, the larger the bcc lattice parameter and the lower the grain size. The highest value of the coercive field is 1420 A/m for Fe–20 wt.% Ni (with shock mode (424 rpm/100 rpm) after 36 h of milling), while the lowest value is 110 A/m for (400 rpm/800 rpm) after 96 h of milling. The milling performed in the friction mode favors the formation of alloys exhibiting a soft magnetic behavior for Fe–20 wt.% Ni alloys. The Mossbauer spectra of the alloys recorded at 77 and at 300 K differ according to the milling conditions and give relevant information on the local structure environment in relation with the nature of the mode used (friction or shock mode).

The so called “vario mill” (P4 Fritsch) planetary ball mill has been used to prepare nanocrystalline Fe-10 wt% Ni and Fe-20 wt% Ni alloys from powder mixtures. For both studied alloys, a disordered body cubic centered (BCC) solid solution has been formed after 36 h of milling. The higher the shock power, the larger the lattice parameter of the investigated systems. It has been found that in friction mode process (FMP), the lower the crystallite size, the lower the lattice strain of the prepared alloy. In shock mode process (SMP), the lower the crystallite size, the higher the lattice strain. FMP has been found to induce a soft magnetic behavior for Fe-10% Ni and F-20% Ni alloys. The highest values of coercivity have been found in materials prepared by SMP.

The mechanical alloying technique has been used to prepare nanocrystalline Fe–10 and Fe–20 wt.% Ni alloys from powder mixtures. The structure and magnetic properties were studied by using X-ray diffraction and hysteresis measurements, respectively. For both alloys studied, a disordered body centered cubic solid solution forms after 24 h milling time. The higher the milling time, the larger the lattice parameter. The steady-state grain size is ≈10 nm. The reduction of the grain size increases the saturation magnetization and decreases the coercivity. Nanocrystalline Fe–10 and Fe–20 wt.% Ni have been shown to exhibit a soft magnetic behavior.

Our previous studies relating to the effect of ball milling (BM) parameters on the microstructure and, consequently, on the magnetic properties have shown that the combination of low values of the plateau rotation Ω and the high vial velocities ω can enhance the cubic phase formation and consequently the coercivity. However, the most relevant parameter remained the ball milling time. Indeed, coercivity and crystallite size exhibit both a regular and similar decrease when mechanical alloying time is increasing. In the case of Co–Ni alloy, a slight increase occurred after 72 h milling. The soft magnetic properties of the alloys (low values of both the squareness ratio M r / M s and the coercivity) indicate that small magnetic particles are typically single domain.

Version Number : 1.0; In this article, we present an identification procedure that allows the determination of the viscoelasticity behavior of different grades of pure bitumen (bitumen 35/50 and bitumen 10/20). The procedure required in the first stage a mechanical response based on macroindentation experiments with a cylindrical indenter. A finite element simulation was performed in the second stage to compute the mechanical response corresponding to a viscoelasticity model described by three mechanical parameters. The comparison between the experimental and numerical responses showed a perfect matching. In addition, the identification procedure helped to discriminate between different bitumens characterized by different asphaltene and maltene contents. Finally, the developed procedure could be used as an efficient tool to characterize the mechanical behavior of the viscoelastic materials, thanks to the quantified relationship between the viscoleastic parameters and the force-penetration response. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3440-3450, 2013

International audience; Planetary ball mill PM 400 from Retsch (with different milling times for X = 400 rpm, x = 800 rpm) and P4 vario ball mill from Fritsch (with different milling conditions (X/x), X and x being the disc and the vial rotation speeds, respectively) are used for obtaining nanocrystalline Fe-10wt% Ni. The structure and magnetic properties are studied by using X-ray diffraction, SEM and hysteresis measurements, respectively. The bcc-Fe(Ni) phase formation is identified by X-ray diffraction. The higher the shock power and the higher milling time are, the larger the bcc lattice parameter and the lower the grain size. The highest value of the coercivity is 1600 A/m for Fe-10 wt.%Ni (with shock mode (424 rpm/100 rpm) after 36 h of milling), while the lowest value is 189 A/m for (400 rpm/800 rpm) after 72 h of milling. The milling performed in the friction mode has been found to lead the formation of alloys exhibiting a soft magnetic behavior for nanocrystalline Fe-10%Ni.

International audience; Physical properties of pure bitumen 35/50 and polymer-modified bitumen 13/40 are studied using needle penetration test and differential scanning calorimetry (DSC). In particular, the mechanical response under indentation conditions is achieved as a function of different loads and temperatures. Our results show that lower temperature susceptibility is associated to larger loads but its change is rather small for the tested bitumens. A pure bitumen 35/50 exhibits a single glass transition temperature for different heating rate whereas modified bitumen 13/40 presents two T-g for different heating rate.

International audience; The mechanical properties and microstructure of modified mortar and concrete using Carbon NanoTubes (CNT) are experimentally studied at 7, 14, 28 and 90 curing days. Part of the formulation, CNT are dispersed in a liquid solution. Different concentrations ranging from 0.01% to 0.06% and 0.003% up to 0.01% are used for mortar and concrete, respectively. Mechanical testing of the modified materials reveals that maximum compressive strength is obtained for CNT concentrations close to 0.01%wt and 0.003%wt for mortar and concrete, respectively. The microstructural characterisation of the modified materials suggests that CNT act as bridges between pores and cracks leading to a reduction in porosity and in turn an increase of compressive strength.

International audience; Urban flooding due to climate changes, dam breaking and drainage systems being overwhelmed by rainfall causes a huge loss to mankind civilization every year all over the world. This work aims to minimize the flooding damage by optimally design the building location and interspace. The velocity, water pressure and the height of water are considered as the main factors to reduce the flooding damage. The multi-objective optimization is implemented by combing several techniques, including Design of Experiment (DOE), Response Surface Method (RSM) and the Genetic Algorithm (GA). The proposed methodology is validated with a case study on the topography of ESTP Cachan.

International audience; Binary 50Ni–50Ti mixture was prepared by mechanical alloying from elemental powders. After 48 h of milling, the nanocrystalline B2-NiTi powder was produced. Then, this as-milled powder was deposited by cold spraying in order to produce a target which can be used to create thin films by magnetron sputtering technique. The objective is to improve the electrical characterizations of the NiTi/SiO2/Si M.O.S structures. Themorphology evolution of the powder particles, the phase identification and the alloying evolution process as function of milling time were studied using scanning electron microscopy, X-ray diffraction and transmission electron microscopy. In addition, the target was also characterized using X-ray diffraction, Scanning electron microscopy, and microhardness measurements. The milling of powders leads to the formation of disorderednanocrystalline B2-NiTi with a crystallite size of about 12 nm and a microstrain of level 2.10%, after 48 h of milling. The microstructure, the composition and grain size of the milled powders for 24 h and 48 h characterized by TEM are heterogeneous. The as-deposited intermetallic NiTi can be retained in the coating with a lattice parameter of 0.3 nm, crystallite size of 14 nm, microstrain and high microhardness of 2% and 694Hv0.25, respectively.

Mg 2 Ni 1− x Mn x ( x = 0, 0.125, 0.25, 0.375) electrode alloys are prepared by mechanical alloying (MA) under argon atmosphere at room temperature using a planetary high-energy ball mill. The microstructures are characterized by XRD and SEM. XRD analysis results indicate that the substitution of Mn for Ni could inhibit the formation of MgNi 2 phase with the increases of x from 0 to 0.375. Replacing Ni with Mn can also promote the formation of the amorphous phase when x increases from 0 to 0.25 for the MA alloys milled for 48 h. The new phase Mg 3 MnNi 2 is formed only when x = 0.375 after 48 h of milling. This new phase belongs to the face-centered cubic lattice ( Fd-3m ) with the lattice constant a being 1.1484 nm. Estimated from the peaks broadening, the crystallite size and lattice strain of Mg 3 MnNi 2 phase are 15.6 ± 3.6 nm and 1.09 ± 0.34%, respectively. Curve fit of XRD shows that amorphous and nanocrystalline Mg 2 Ni coexist in the Mg 2 Ni 1− x Mn x ( x = 0, 0.125, 0.25) alloys milled for 48 h. The SEM observation reveals that all the MA alloys particles are mainly flaky and show cleavage fracture morphology and these particles are agglomerates of many smaller particles, namely subparticles. Electrochemical measurements indicate that all MA alloys have excellent activation properties. The discharge capacities of MA alloys increase with the prolongation of milling time. For 16 h of milling, with the increase of Mn content, the discharge capacities of Mg 2 Ni 1− x Mn x ( x = 0, 0.125, 0.25, 0.375) MA alloys monotonously decrease. For 24 h of milling, the discharge capacities of the Mg 2 Ni 1− x Mn x ( x = 0, 0.125, 0.25, 0.375) alloys also show a rough tendency to decrease with the increase of Mn content except Mg 2 Ni 0.875 Mn 0.125 MA alloy. On the other hand, for 48 h of milling, as the rise of Mn content from x = 0.125 to 0.375, the discharge capacities increase. Mg(OH) 2 is formed during charge/discharge cycles in the KOH solution for all MA alloys. After 48 h of milling, the substitution of Mn for Ni for x = 0.25 improves the cycle stability at the expense of decreasing the discharge capacity. In contrast, Mg 3 MnNi 2 phase is relatively stable during charge/discharge cycles and therefore can significantly enhance the cycle stability under simultaneously maintaining a high discharge capacity.

International audience; Abstract. In this paper, the FeSiBNbCu and FeSiBNbCu-Al coatings were synthesized using cold spray technique in order to produce ferromagnetic materials. Ultra-fine grain coatings are obtained using FINEMET nanostructured powders mixed with Aluminum. Various percentages of Aluminum characterized by its low hardness were taken in account. The obtaining coatings were formed of Aluminum matrix and randomly distribution of FINEMET particles. Indeed, magnetic measurements revealed a soft magnetic character for all the powders and the coatings. 25% of Al was considered as ideal to produce a homogenous coating with good soft magnetic properties.

International audience; The aim of this paper is to study the corrosion resistance of industrial coatings of metallic alloys including certain amount of process-induced porosity. Surface damages during a simulated corrosion process are investigated using Monte Carlo simulation technique and compared to corrosion response (dissolution currents). In this simulation, a 3D grid of the coating is subject to an electrolyte attack under potentiostatic conditions. The surface damages are related to a controlled dissolution process governed by dissolution probability, roughness, porosity size and fraction. In order to validate the model results, theoretical I-fit) curves are compared to corrosion behaviour of Fe-40A1 samples pointing out critical parameters affecting current density and exposed area. Predictions relating the porosity level to corrosion behaviour are established and discussed. The main conclusions focus on a primary effect of pore size and connectivity and a secondary effect of porosity leve! l in the considered process window (porosity levels between 5.8% and 7.8%). The experimental work shows that the porosity effect could not explain all observed trends and a deeper examination of the microstructure reveals another candidate (unmolten particles) which is expected to vary both pore connectivity and dissolution events

Fe–10 wt% Ni and Fe–20 wt% Ni nanostructured alloys were prepared using a planetary ball mill P 4 vario mill from Fritsch. The Fe (Ni) BCC solid solution was identified by X-ray diffraction, allowing also to follow the size and shape of crystalline grains. The higher the shock power, the smaller the grain size. The Mossbauer spectra of the nanostructured powders recorded at 77 and 300 K differ according to the shock power and the friction energy component while the hyperfine structure gives relevant information on the local structure environment of Fe atoms in relation with the milling mode process (shock or friction mode).

An artificial neural network (ANN) methodology was applied to relate the powder-milling process parameters to the magnetic properties of Fe–10%Ni and Fe–20%Ni alloy materials. An optimization procedure based on ANN training and testing steps has been developed to predict magnetic properties over a large range of process parameters. A good agreement was found between experimental and predicted results with an average standard deviation between experimental and predicted values less than 6%. The following features have been anticipated: (i) the higher disc rotation speed and the lower the vial rotation speed, the higher the coercivity; (ii) the lower the disc rotation speed and the higher the vial rotation speed, the lower the coercivity.

Construction materials are an essential need for humans. After Water, concrete is the most widely used material in the world and cement production is constantly increasing due to the increase in the world population. In 2010, the annual cement production reached 3.3 billion tonnes. An increase of +6.9% was recorded in 2015 for a production that reached 4.6 billion tonnes.Studies conducted on the environmental impact of the clinker manufacturing process have revealed that for a production of one tonne of clinker, a quantity of 0.7 to 0.8 tonnes of CO2 is released into the atmosphere or an annual emission of 2.8 billion tonnes of CO2. These greenhouse gas emissions are responsible for 5% of global emissions. In order to reduce this impact, solutions already proposed such as the use of alternative fuels for clinker manufacture, the partial substitution of cement by industrial co-products or carbon capture and storage.This thesis is part of a desire to reduce the carbon impact in the manufacture of construction materials by introducing the mechanosynthesis process into the production process of clinker and cement as well as geopolymers.The thesis work has been divided into 3 main parts:The first part concerns the mechanosynthesis process optimization by adding process control agents (PCAs). The use of these agents for the grinding of fly ash and blast furnace slag has reduced the milling time to 15 minutes, whereas without PCA, 1 hour milling time is required, or even 3 hours for optimal milling. Cement pastes which we have substituted up to 50% clinker with industrial co-products activated by mechanosynthesis with PCAs (we have used alcohol and water) have shown higher mechanical performance than those prepared with 100% Portland cement.Cement pastes prepared with a substitution of 50% milled slag 15 min + 4% alcohol has shown an improvement in mechanical performance (compression) of + 10%, + 15% and + 40% compared to a reference cement paste for 7, 28 and 90 days respectively.The second part aims to propose a clinkerization process by indirect mechanosynthesis. We have used limestone and clay (traditional products for clinker manufacturing) to produce an equivalent clinker. To achieve our objective, we have used indirect mechanosynthesis, which consists of coupling a mechanical activation with short milling time and a heat treatment not exceeding 900°C. This technique has allowed us to produce the essential compounds of clinker, C3S alite (Ca3SiO5), β-C2S belite (Ca2SiO4) and C3A aluminates.The last part is focused on the direct mechanosynthesis process used for the production of a ready-to-use geopolymer powder only by adding water. This process consists of mixingaluminosilicates such as slag, fly ash or metakaolin with chemical activators by grinding to obtain a final geopolymer product.Geopolymer paste formulations have been made and encouraging results in terms of compressive strength have been obtained., Les matériaux de construction constituent un besoin indispensable pour les êtres humains. Le béton est, après l’eau, le matériau le plus utilisé dans le monde et la production de ciment est en perpétuelle augmentation du fait de l’accroissement de la population mondiale. En 2010 la production annuelle de ciment a atteint les 3,3 milliards de tonnes, une progression de +6,9% a été constatée en 2015 pour une production de ciment qui a atteint 4,6 milliards de tonnes.Des études menées sur l’impact environnemental du procédé de fabrication du clinker ont révélé que pour une production d’une tonne de clinker, une quantité de l’ordre de 0,7 à 0,8 tonne de CO2 est rejetée dans l’atmosphère, soit une émission annuelle de 2,8 milliards de tonnes de CO2. Ces rejets de gaz à effet de serre sont responsables de 5% des émissions mondiales. Afin de réduire cet impact, des solutions ont déjà été proposées telles que l’utilisation de combustibles alternatifs pour la fabrication du clinker, la substitution partielle du ciment par des coproduits industriels ou le captage et stockage du carbone.Cette thèse s’inscrit dans une volonté de réduire l’impact carbone dans la fabrication des matériaux de construction et cela par l’introduction du procédé de mécanosynthèse dans le processus de production du clinker et du ciment ainsi que des géopolymères.Le travail de thèse a été divisé en 3 grandes parties :La première concerne l’optimisation du procédé de mécanosynthèse par l’ajout d’agents de contrôle (process control agents) « PCA ». L’utilisation de ces agents pour le broyage de cendres volantes et de laitiers de hauts fourneaux a permis de réduire la durée du broyage à 15 minutes, alors que sans PCA un broyage de 1h est nécessaire, voire 3h pour un broyage optimal. Les pâtes cimentaires pour lesquelles nous avons substitué jusqu’à 50% de clinker par des coproduits industriels activés par mécanosynthèse avec des PCA (nous avons utilisé de l’alcool et l’eau) ont montré des performances mécaniques supérieures à celles préparées avec 100% de ciment Portland.Les pâtes cimentaires préparées avec une substitution de 50% de laitier broyé 15 min + 4% d’alcool ont montré une amélioration des performances mécaniques (compression) de + 10%, + 15% et + 40% par rapport à une pâte de ciment référence respectivement pour 7, 28 et 90 jours.La deuxième partie vise à proposer un procédé de clinkérisation par mécanosynthèse indirecte. Dans cette partie nous avons utilisé dans un premier temps du calcaire et de l’argile (produits classiques pour la fabrication du clinker) pour la production d’un clinker équivalent. Pour atteindre notre objectif nous avons utilisé la mécanosynthèse indirecte qui consiste à coupler une activation mécanique de courte durée et un traitement thermique ne dépassant pas les 900°C. Cette techniquenous a permis de produire les composés indispensables au clinker, l’alite C3S (Ca3SiO5), la belite β-C2S (Ca2SiO4) et les aluminates C3A.La dernière partie avait pour but d’utiliser le procédé de mécanosynthèse directe pour la production d’une poudre géopolymère prête à l’emploi seulement par addition d’eau. Ce procédé consiste à mélanger des aluminosilicates tels que des laitiers, des cendres volantes ou du métakaolin avec des activateurs chimiques par broyage pour l’obtention d’un produit géopolymère final.Des formulations de pâtes géopolymères ont été faites et des résultats encourageants en termes de résistance à la compression ont été obtenus.

In France, it has been numerated more than 340 Million Tons of deconstruction wastes in the field of civil and public works.Among of these wastes, which are prone to be recycled if they are inert, are old aggregates concretes, especially which were produced in the 1960’s. The manufacturing process of cement on an industrial scale was similar to what is done today. Where, it cannot be excluded that these concretes may contain hexavalent chromium. However, the directive 2003/CE/53 concerning the production of cement limits the content of hexavalent chromium to 2 mg per kg of dry matter. Therefore, it is essential to study, before any upgrading project, the atmospheric interactions with the cement matrix and the degradation by rainwater during their landfill or during their life cycle.The thesis work takes part of a feasibility study on the recycling of waste deconstruction containing Cr (VI) and having undergone different types of natural degradations, including atmospheric carbonation. An environmental impact study has been performed on the basis of leaching tests on monolithic and granular materials. In addition, pH impact study on release conditions was also performed. The interpretation of the experimental results is based on the use of kinetic models, in particular the model of Côte & Constable (1985), as well as the solutions of interpretations graphs of the known different standards.The experimental campaign is focused on mortars confectioned from aggregates recycled at 30% and 100% substitution rates as well as recycled aggregates in the gross state. The obtained results are shown that the materials studied (mortars or aggregates alone) are inert with respect to the release of hexavalent chromium. t has been shown, independently from the origin of the recycled aggregates, their chemical composition, their mineralogy and their substitution rate in mortars, that the release of chromium hexavalent remains negligible. Similarly, an in-depth study was conducted on the chromium structure within the cementitious matrix under these two stable forms, trivalent and hexavalent. The results showed that chromium tends to stabilize in ettringite, with structure called Cr-ettringite in the case of Cr (VI) and in bentorite structure in the case of Cr (III).Finally, it has been shown that the cement matrix carbonation has an aptitude to trap and immobilize Cr (VI)., En France, on compte plus de 340 millions de tonnes de déchets de déconstruction dans le secteur du bâtiment et des travaux publics. Parmi ces déchets, susceptibles d’être valorisés à condition qu’ils soient inertes, on trouve les granulats issus de vieux bétons et notamment des bétons produits dans les années 1960. Le processus de fabrication du ciment à l’échelle industrielle était tel qu’aujourd’hui, on ne peut pas exclure que ces bétons puissent contenir du chrome hexavalent. Mais la directive 2003/CE/53 concernant la production du ciment limite la teneur en chrome hexavalent à 2mg par kg de matière sèche. Il est par conséquent indispensable d’étudier, avant tout projet de valorisation, les interactions atmosphériques avec la matrice cimentaire et les dégradations par les eaux de pluie lors de leur mise en décharge ou durant leur cycle de vie.Le travail de cette thèse s’inscrit dans une étude de faisabilité du recyclage des déchets de déconstruction contenant du Cr (VI) et ayant subi différents types de dégradations naturelles, notamment la carbonatation atmosphérique. Une étude d’impact environnemental a été effectuée sur la base d’essais de lixiviation sur des matériaux de types monolithique et granulaire. Une étude de l’impact du pH sur les conditions de relargage a également été réalisée. L’interprétation des résultats expérimentaux utilise des modèles cinétiques, en particulier le modèle de Côte et Constable (1985), ainsi que les solutions d’interprétations graphiques des différentes normes utilisées.La campagne expérimentale a porté sur des mortiers confectionnés à base de granulats recyclés à des taux de 30% et 100% de substitution ainsi que sur des granulats recyclés à l’état brut. Les résultats obtenus ont montré que les matériaux étudiés (mortiers ou granulats seuls) sont inertes vis à vis du relargage du chrome hexavalent. Il a été démontré également, indépendamment de l’origine des granulats recyclés, de leur composition chimique et minéralogique et de leur taux de substitution dans les mortiers, que le relargage du chrome hexavalent reste négligeable. De même, une étude approfondie a été menée sur la structure du chrome au sein de la matrice cimentaire sous ces deux formes stables, trivalente et hexavalente. Les résultats obtenus ont montré que le chrome a tendance à se stabiliser dans l’ettringite, appelé Cr-ettringite dans le cas du Cr (VI) et dans la bentorite dans le cas du Cr (III).Enfin, il a été mis en évidence que la matrice cimentaire carbonatée a une aptitude à immobiliser le Cr (VI).