Polyéthylène de masse molaire très élevée

Résumé

Le polyéthylène de masse molaire très élevée (UHMPE) est un polyéthylène haute densité (PE-HD) caractérisé par une excellente tenue à l'abrasion. En raison de sa très forte masse molaire, ce polyéthylène linéaire présente un indice de fluidité très faible, sa mise en forme est donc difficile. Des fibres de module très élevé peuvent être obtenues après étirage. Synonymes UHMWPE pour en (parfois abrégé en UHMW), également connu sous le nom de polyéthylène à haut module (HMPE, en) ou de polyéthylène haute performance (HPPE, en). Présentation Les chaines du UHMPE sont extrêmement longues, de l'ordre de plusieurs centaines de milliers d'unités monomères. La plus longue chaîne sert à transférer la charge plus efficacement à la chaîne principale du polymère par un renforcement des forces intermoléculaires. Il en résulte un matériau très résistant, avec actuellement la plus grande résistance aux chocs de tous les composés thermoplastiques. Il est très résistant aux pro

Source officielle

https://fr.wikipedia.org/wiki/Poly%C3%A9thyl%C3%A8ne_de_masse_molaire_tr%C3%A8s_%C3%A9lev%C3%A9e

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Ultra-high performance fiber reinforced concretes (UHPFRC) have demonstrated their potential to contain the explosion of maintenance costs (Economy and Environment) for civil engineering structures, due to their extremely low permeability associated with the outstanding mechanical properties. Substitution of embodied-energy (EE)-costly components of UHPFRC such as clinker and steel fibers, is the next step towards sustainability, to make it even more efficient and more environment-friendly. In this study, a strain hardening UHPFRC mix with two main modifications has been developed in which (1) 75% of steel fibers have been replaced by ultra-high molecular weight polyethylene (UHMWPE, henceforth referred to as PE) fibers and (2) 50% volume of cement type CEM I have been replaced with limestone filler. The effect of the fiber orientation and the specimen thickness on the mechanical properties of such mixes have been investigated. The mechanical properties have been investigated using direct tensile test, and 4-point bending test. Finally, the dramatic effect of fiber orientation on the ultimate strength and deformability has been demonstrated. Moreover, the results confirm that the specimen thickness affects the deformation capacity of the specimens. Finally, improvements in terms of reduction of EE of the proposed mixes, are highlighted.

SPRINGER2018

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Next generation UHPFRC for sustainable structural applications

Emmanuel Denarié, Amir Hajiesmaeili

Over the last few decades, ever-increasing demands of society to the built environment have continually increased consumption of energy and materials for the construction and maintenance of structures. Meanwhile, Strain Hardening Ultra High-Performance Fiber Reinforced Concrete (SH-UHPFRC) have the potential to be one of the solutions to contain the explosion of maintenance costs (Economy and Environment), considering their extremely low permeability associated to outstanding mechanical properties and load bearing efficiency compared to deadweight. The objective of this research is to further improve the already established concept of UHPFRC application for rehabilitation. This paper reports firstly on the development and validation of new low Embodied Energy (EE) SH-UHPFRC mixes with 50 % clinker replacement by Supplementary Cementitious Materials and replacement of steel fibers by ultra-high molecular weight polyethylene (UHMW-PE) ones. In a second step, the mechanical and protective properties of the mixes are investigated with a special emphasis on their quasi-static tensile response, and transport properties. Finally, the dramatic improvement in terms of reduction of EE and deadweight of the proposed mixes is demonstrated.

2018

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Ultra-High Performance Fiber Reinforced Concretes (UHPFRC) have demonstrated their potential to contain the explosion of maintenance costs (Economy and Environment) for civil engineering structures, due to their extremely low permeability associated with the outstanding mechanical properties. Substitution of Embodied- Energy (EE)-costly components of UHPFRC such as clinker and steel fibers, is the next step towards sustainability, to make it even more efficient and more environment- friendly. In this study, a strain hardening UHPFRC mix with two main modifications has been developed in which (1) 75% of steel fibers have been replaced by ultra-high molecular weight polyethylene (UHMWPE, henceforth referred to as PE) fibers and (2) 50% volume of cement type CEM I have been replaced with limestone filler. The effect of the fiber orientation and the specimen thickness on the mechanical properties of such mixes have been investigated. The mechanical properties have been investigated using direct tensile test, and 4-point bending test. Finally, the dramatic effect of fiber orientation on the ultimate strength and deformability has been demonstrated. Moreover, the results confirm that the specimen thickness affects the deformation capacity of the specimens. Finally, improvements in terms of reduction of EE of the proposed mixes are highlighted.

Springer Netherlands2017

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