Growing environmental concerns are leading the construction industry to look for innovative, reliable and sustainable materials that can replace the synthetic fibers usually used for reinforcement of building materials with natural fibers. Natural fibers are considered as potential alternatives, due to their environmental sustainability and availability. Accordingly, and in order to develop new regional applications based on vegetal fibers, the FIBRABETON project, financed by the ADEME, the Grand-Est region and the FEDER, has been developed. This project associates three partners: the French cement manufacturer VICAT, which offers fluid screed solutions, the company Fibres Recherche Développement (FRD), which prepares vegetal fibers, and the ESTP, which carries out research and works on the characterization of fluid screed formulations. The objective of the thesis is to develop fluid screed formulations by substituting synthetic polypropylene fibers with vegetal fibers, while achieving at least similar performances. This research focused on the use of soft and rigid vegetal fibers (hemp, flax, miscanthus and bamboo) in the formulation of anti-cracking screed (monofibered) and structural screed (bifibered). The four natural fibers are of two sizes, 5 mm and 15 mm, and were used at different contents. An experimental program focused on the characterization of the fibers on the physicochemical level (composition, structure, ...) has been performed. The influence of fiber type, content and size were investigated and their impact on the performance of fiber screeds was determined by workability, air content and bulk density control tests. Heat of hydration parameters, shrinkage free deformations and mechanical properties (flexural and compressive) were also studied. In addition, scanning electron microscopy was used to characterize the surface condition of the soft and rigid fibers and the interface with the cementitious matrix as well as their dispersion. The main results obtained in relation to the length of the fiber and its content on the mechanical performances are in accordance with those of the literature. Namely, the higher the fiber content, the higher the flexural strength but the lower the compressive strength. Overall, the results of flexural strength and compressive strength are better with vegetal fibers than those obtained with synthetic fibers. As regards the fresh state, the spreading is more fluid in the case of rigid fibers than that of soft fibers. This result is to be corroborated with the aspect ratio of the soft fiber, which is higher, inducing more occluded air and therefore less bulk density. In the case of rigid fibers, since the aspect ratio is lower, the flexural strength values obtained are high and this with higher content. In the case of the mono-fibered screed formulation, the optimal content is 1.2 kg/m3 of 5 mm hemp in order to obtain the optimal characteristics in terms of workability and mechanical performance. In the case of the bifibered formulation (soft fibers - rigid fibers), in terms of flexural strength, most of the proposed formulations exceed those based on synthetic fibers. SEM images of the soft fibers show a change in shape when embedded in a cementitious matrix. This change affects the aspect ratio. A linear regression numerical model was developed for the prediction of the mechanical strengths of mono and bi-fibered fluid screed formulations
Authors
- Bibliographic Reference
- Sergio Pons Ribera. Valorisation des fibres végétales dans des matériaux cimentaires : application dans les formulations de chapes fluides. Génie civil. Université Gustave Eiffel, 2022. Français. ⟨NNT : 2022UEFL2040⟩. ⟨tel-04018330⟩
- HAL Collection
- ['STAR - Dépôt national des thèses électroniques', 'Génie Civil']
- HAL Identifier
- 4018330
- Institution
- École Spéciale des Travaux Publics, du Bâtiment et de l'Industrie [Paris]
- Laboratory
- Institut de Recherche en Constructibilité
- Published in
- France
Table of Contents
- CHAPITRE I : 22
- 1. Introduction 23
- 2. Généralités sur les fibres naturelles 24
- 2.1. Structure et morphologie 25
- 2.2. Composition chimique 27
- La cellulose : 29
- La lignine : 30
- La pectine : 32
- 2.3. Méthodes d’extraction 33
- a) Rouissage biologique : 34
- b) Rouissage chimique : 35
- c) Rouissage mécanique : 36
- 2.4. Propriétés physiques et mécaniques 36
- 2.5. Avantages et points de faiblesse des fibres végétales 39
- Avantages : 39
- Points de faiblesse : 40
- 3. Généralités sur les bétons fibrés 41
- 3.1. Introduction 41
- 3.2. Valorisation des fibres naturelles dans les matériaux cimentaires 42
- 3.3. Comportement des fibres naturelles dans une matrice cimentaire 43
- Modification de la matrice : 44
- Processus de détérioration des fibres en milieu alcalin : 45
- Modification des fibres : 47
- 3.4. Propriétés à l’état frais 47
- 3.5. Propriétés mécaniques 49
- 3.6. Propriétés de transfert 50
- 4. Compatibilité à l’interface fibre/matrice cimentaire 52
- 4.1. Préparation et traitement des fibres naturelles 61
- 4.2. Influence du type de fibre 63
- 4.3. Influence de la taille des fibres 66
- 4.4. Influence de la teneur en fibres 67
- CHAPITRE II : 69
- 2. MATERIAUX ET METHODES 70
- 1. Introduction (1) 70
- 2. Les types de fibres utilisés pour la formulation des chapes 70
- 3. Les matériaux utilisés pour la formulation des chapes et leurs dosages 75
- 3.1. Le ciment : 75
- 3.2. L’adjuvant : 76
- 3.3. Filler calcaire : 76
- 3.4. Sable naturel : 77
- 3.5. Dosages de la chape fluide : 80
- 4. Préparation des échantillons (gâchées) 81
- 4.1. Le protocole de malaxage : 81
- 5. Mesure du coefficient d’absorption d’eau des fibres végétales 81
- 6. Caractérisation à l’état frais 83
- 6.1. Essai d’étalement 83
- 6.2. Mesure de la masse volumique (NF-EN 12350-6) 84
- 6.3. Mesure de l’air occlus (NF-EN 12350-7) 84
- 7. Caractérisation à l’état durci 85
- 7.1. Mesure de retrait 85
- 7.2. Essai de flexion 3 points : 86
- 7.3. Essai de compression : 87
- 8. Analyse physico-chimique 88
- 8.1. Diffraction des rayons X 88
- 8.2. Analyse par fluorescence des rayons X (FRX) 89
- 8.3. La spectroscopie infrarouge à transformée de Fourier (FTIR) 90
- 8.4. Analyse thermogravimétrique (ATG) 90
- 8.5. Calorimètre Langavant 91
- 9. Microscopie électronique à balayage (MEB) et microscope optique : 92
- 10. Pycnomètre à gaz hélium : 93
- REFERENCES BIBLIOGRAPHIQUES 181
- Références bibliographiques 182
