Portail des publications scientifiques IMT Mines Alès
Not a member yet
5198 research outputs found
Sort by
Chapter 8 - Fire performance of hemp concrete
No full textInternational audienceThe construction field is one of the main sources of greenhouse gas emissions on a global scale, therefore, in response, innovative materials with low carbon footprint are being developed for construction. Biobased resources, such as crop straw, hemp shives or rice husks, can be mixed with a mineral binder to produce biobased concretes. They can be used as insulating materials at low density (150–500 kg/m3), or for thermal inertia contribution at intermediate density (500–1200 kg/m3) and high density (1200–1800 kg/m3). The fire performance of these materials deserves further investigations. In this chapter, three main aspects of the fire behavior of a biobased concrete are discussed: the fire reaction, the fire resistance, and the smoldering fire. Briefly, the first one explains how the material directly contributes to the fire development, the second one indicates the ability of a structure to protect people situated in an adjacent room during a given duration from being impacted by the fire (fire resistance) and the last one is the phenomenon of slow and flameless combustion, which is often observed in insulating materials. Finally, some recommendations for future research are proposed
Optimization of interfacial adhesion and mechanical performance of flax fiber-based eco-composites through fiber fluorination treatment
No full textInternational audienceNatural fibers, such as flax, are more and more used as biobased reinforcement for eco-composites manufacturing but their natural polarity makes them incompatible with most polymers (mostly dispersive). Nowadays, treatments such as torrefaction are known to reduce the polarity of natural fibers and thus increase the mechanical performance of the reinforced composites. However, these treatments could harm fibers and limit the gain in performance. Thereby, the use of a controlled fluorination treatment allowed, via the grafting of fluorine on the fiber surface, to decrease the polarity of these fibers while maintaining an equivalent Young's modulus and limiting the reduction of at break performance to just ∼30 %. Therefore, by incorporating these fluorinated reinforcements in an epoxy matrix and by mechanically testing these composites, not only superior mechanical performances to those reinforced by raw fibers, but also superior to torrefied fiber-reinforced composites were measured, e.g.: the flexural modulus increased by 25 % after fluorination vs. 10 % after torrefaction and the flexural strain at break was enhanced by 10 % after fluorination vs. decrease by 35 % after torrefaction)
An Extensive Study of an Eco-Friendly Fireproofing Process of Lignocellulosic Miscanthus × giganteus Particles and Their Application in Flame-Retardant Panels
No full textInternational audienceIncreasing the flame retardancy of lignocellulosic materials such as Miscanthus × giganteus can effectively enable their wide use. This study examines the fireproofing process of Miscanthus particles using an eco-friendly process by grafting phytic acid and urea in aqueous solution. Miscanthus particles underwent a steam explosion step before being grafted. Fireproof binderless particle panels were manufactured from miscanthus particles with or without adding olive pomace by hot-pressing. The effect of the steam explosion and/or the flame-retardant treatment on the morphology, chemical composition and thermal stability of the particles, as well as the thermal stability of the panels, was investigated. The results showed that water impregnation followed by a steam explosion at 210 °C for 8 min resulted in particles that were rich in lignin and more homogeneous in size (length and width). Fireproof particles were produced with relatively low P and N contents. The flame retardancy of the binderless particle panels was significantly improved when using miscanthus particles treated with phytic acid and urea, as shown by a reduced heat release (HRR) and an increased time-to-ignition. However, the presence of olive pomace significantly decreased the flame retardancy of the panels. Binderless particle panels prepared from grafted miscanthus particles showed the best fire properties and are considered fireproof
Phosphoramidate functionalization of hybrid chitosan/SiO2 beads for efficient sorption of ruthenium and application on seawater as a case study
No full textInternational audienceRuthenium removal from complex solutions (highly saline effluents, seawater) is a critical challenge. Herein, the sorption capacity of chitosan/SiO2 composite beads (Ch-Si) for ruthenium nitrosyl is increased three-fold after phosphoramidate grafting (DPA-Ch-Si, 1.6 mmol Ru g−1) at pH 5. Uptake kinetics and sorption isotherms are compared at pH0: 3, 5 and 10; playing with the mode of agitation (mechanical, MA, vs. ultrasonic treatment, UT). The sorbent maintains good sorption capacities at pH 3 and 10. Uptake kinetics modeled by pseudo-first order rate equation is boosted by functionalization. For Ch-Si, sorption isotherms are modeled by the Langmuir or Sips equations (depending on the pH), while for DPA-Ch-Si the best fits depend on pH, temperature and mode of agitation. Ruthenium sorption is spontaneous and endothermic for the two sorbents. For DPA-Ch-Si, the sorption capacity increases from 1.62 to 1.70 mmol Ru g−1 to 2.23–2.32 mmol Ru g−1 (T increasing from 21 to 50 °C). Nitric acid solution (0.3 M) reveals highly efficient for back extraction; ruthenium is completely released in <15 min. The functionalized sorbent can be reused for a minimum of 10 cycles, with limited loss in performance. Phosphoramidation improves sorption selectivity for the treatment of equimolar multicomponent solutions (Na, Ca, Mg, Fe, Al, U, and Nd). The effect of pH on sorption selectivity is evaluated in simple multi-metal solutions and complex environment. In seawater, the selective recovery of ruthenium is favored at pH close to 10. These tests confirm the promising perspectives offered for ruthenium removal from complex environments. Physicochemical characterizations of the sorbent (and their modes of interaction with ruthenium nitrosyl) included SEM, BET, TGA, FTIR, XPS, and elemental analyses
A new ISO standard for the experimental characterization of in-plane permeability of fibrous reinforcements
No full textInternational audienceDuring Liquid Composite Molding, a fibrous reinforcement is impregnated with liquid resin. Process design requires knowledge of the reinforcement permeability for fluid flow, but until recently, there has been no standard available for its measurement. In 2023, following decades of benchmarking activities and a standardization project, an ISO standard for the experimental characterization of in-plane permeability of fibrous reinforcements for liquid composite molding was finally published. It focuses on the experimental characterization of unsaturated in-plane permeability and specifies the requirements for test equipment, methods and data analysis. Given the deficiency of standardized procedures within the composites industry, this paper intends to provide an example of the steps towards standardization and summarizes lessons learned. It illustrates the research milestones that led to the establishment of the standard, promotes the standard by detailing its general content and notable features and finally gives explanations and reasoning behind the developed guidelines
Role of ice formation mechanisms occurring inside stylolite on limestone tilestone frost susceptibility
No full textInternational audienceFreeze temperature and ice quantity formed inside porous media has been investigated on limestone tilestone samples by Differential Scanning Calorimetry (DSC) measurements. The aim was to determine the role of these stone frost features on limestone damage to Freeze-Thaw (FT) cycles, in relation to the presence of stylolite inside their structure. In fact, the presence of stylolite inside the structure leads to increase locally the pore rate and size, with connected pores. This implies a local increase of ice quantity formed at the surround of stylolite. Damage is thus associated to a heterogeneous nucleation, a rapid growth and ice-front propagation inside pores induced by the presence of stylolite. Specimens exhibiting an increase of quantity of ice formed inside their stylolite – of more than 30% compared to host rock – were damaged by freeze/thaw cycles. Furthermore, stones with freezing temperature lower than the minimum of FT cycles temperature are frost resistant. Finally, low-temperature calorimetry appears to be a practical and cheap method for quickly assessing frost limestone susceptibility. For example, this method can benefit some modest heritage constructions in UNESCO World Heritage site ‘Causse & Cevennes’, made by craftsmen who need to quickly know the frost resistance of the stones they use
Synergie entre traitement biologique et électro-oxydation pour une approche intégrée du traitement des micropolluants organiques à concentrations traces dans les eaux usées urbaines
No full textThe recent revisions of the European Water Framework Directive highlight the urgent need for wastewater treatment technologies capable of effectively removing both organic matter and micropollutants while ensuring energy viability. In this context, advanced strategies must achieve high removal efficiencies without compromising sustainability. The present study investigates the integration of granular anaerobic membrane bioreactors (GAnMBR) with electrochemical treatment. A comparative assessment was first conducted between a GAnMBR and its electro-assisted configuration (eGAnMBR), focusing on organic matter removal, membrane fouling, biogas production, and energy balances. In a second phase, the permeates from both systems were treated by electro-oxidation on boron-doped diamond electrodes to evaluate the removal of selected micropollutants from different chemical families: carbamazepine, diuron, and PFOS. A design of experiments and ANOVA modeling were applied to identify the operating conditions that optimize contaminant removal and energy efficiency. In parallel, analytical protocols based on solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry were developed and validated for the trace-level quantification of micropollutants and their degradation products in complex aqueous matrices. This work provides new insights into the performance and limitations of coupling anaerobic membrane processes with electrochemical treatment, and contributes to the development of sustainable and energy-efficient wastewater management strategies for the treatment of emerging contaminantsLes récentes révisions de la Directive-Cadre européenne sur l’Eau mettent en évidence la nécessité urgente de technologies de traitement des eaux usées capables d’éliminer efficacement la matière organique et les micropolluants tout en assurant la viabilité énergétique. Dans ce contexte, des stratégies avancées doivent atteindre une forte efficacité d’abattement sans compromettre la durabilité. La présente étude examine l’intégration de bioréacteurs à membrane anaérobie granulaire (GAnMBR) avec un traitement électrochimique. Une évaluation comparative a d’abord été menée entre un GAnMBR et sa configuration électro-assistée (eGAnMBR), en mettant l’accent sur l’élimination de la matière organique, le colmatage membranaire, la production de biogaz et les bilans énergétiques. Dans un second temps, les perméats issus des deux systèmes ont été traités par électro-oxydation sur électrode diamant dopé au bore afin d’évaluer l’élimination de micropolluants ciblés, de différentes familles chimiques : la carbamazépine, le diuron et le PFOS. Un plan d’expériences et une modélisation ANOVA ont été appliqués pour identifier les conditions opératoires optimisant l’abattement des contaminants et l’efficacité énergétique. En parallèle, des protocoles analytiques basés sur l’extraction en phase solide couplée à la chromatographie liquide-spectrométrie de masse en tandem ont été développés et validés pour la quantification à l’état de traces des micropolluants et de leurs produits de dégradation dans des matrices aqueuses complexes. Ce travail apporte de nouvelles connaissances sur les performances et les limites du couplage entre procédés membranaires anaérobies et traitement électrochimique, et contribue au développement de stratégies de gestion des eaux usées durables et économes en énergie pour le traitement des contaminants émergents
Niovelius : un jeu hybride d’enquête pour former à la gestion des pollutions maritimes accidentelles par produits chimiques
No full textNational audiencePour former à la gestion des pollutions maritimes, une équipe pluridisciplinaire d’IMT Mines Alès et de l’Université Lyon 2 a créé Niovelius, un jeu hybride mêlant enquête, manipulation d’objets et application numérique. En observant les joueurs progresser, coopérer et raisonner, les concepteurs montrent comment le ludique devient un levier pour aborder des situations complexes — et pourquoi le numérique seul ne suffit pas
