Etude de la faisabilité d'un composite à matrice cimentaire renforcé de fibres de jute

Le domaine de la construction doit jouer un rôle important dans la résolution des problèmes environnementaux lies au recyclage et l'exploitation de la biomasse. Dans la catégorie des matériaux cimentaires, différents types de déchets et coproduits issus de l'agriculture ont déjà été utilises, soit sous forme de particules, en remplacement total ou partiel des granulats minéraux, soit sous forme de fibres pour renforcement. Dans cette, étude nous nous sommes intéresses au potentiel d'utilisation des fibres de jute comme éléments de renfort pour mortiers. La fibre de jute a été utilisée en substitution partielle du sable à différents taux, le mortier de référence étant sans fibres. Un protocole d'essais expérimentaux à été mène pour étudier les composites a l'état frais et a l'état durci. La compatibilité chimique des fibres de jute avec le ciment à été évaluée a l'aide des tests d'hydratation qui consistent a enregistrer l'élévation de température au cœur du composite lors des réactions exothermiques des composants du ciment avec l'eau de gâchage. Les résultats révèlent un faible indice d'inhibition confirmant la compatibilité de la fibre avec le ciment. Les essais mécaniques montrent une baisse des performances avec l'augmentation du taux de fibres, mais un gain substantiel en poids.Mots clés: Composite cimentaire - Mortier de fibres - Fibres de jute - Compatibilité chimique. Construction field has to play an important role in resolving environmental problems related to recycling and exploitation of the biomass. In the category of cementitious materials, various types of wastes and byproducts derived from agriculture have already been used, either as particles, in total or partial replacement of mineral aggregates, or as fibers for reinforcement. In this study we were interested at the potential use of jute fibers as reinforcing elements for mortars. The jute fiber was used in partial replacement of sand at different rates; the control mortar was without fibers. A Memorandum of experimental tests was conducted in order to study the composite in fresh and hardened state. The chemical compatibility of jute fibers with cement was evaluated using tests of hydration which consist in recording the temperature rise in the heart of the composite during the exothermic reactions between the components of the cement and the mix water. The results of these tests revealed very low index of inhibition confirming the compatibility of the jute fiber with cement. The mechanical tests showed a decrease in performances according to the increase of fiber and a substantial gain weight.Keywords: Cementitious composite - Fiber mortars - Jute fibers - Chemical compatibility

Valorization of mud from Fergoug dam in manufacturing mortars

The production of calcined mud, with pozzolanic properties, from the large quantities of sediments dredged from Algerian dams, could be a good opportunity for the formulation of high performance mortars and pozzolanic concretes, with lower costs and less greenhouse gas (CO2) emissions. The optimal temperatures selected for calcination were 750, 850 and 950 °C. The burning operation was continuous over a period of 3 h. Therefore, a series of physical, chemical, mechanical and microstructural analyses were conducted on sediment samples, collected from the waters of Fergoug dam. The results obtained from the analyses of the calcined mud, from the dam, allowed saying that mortars with different percentages of that mud represent a potential source of high reactivity pozzolanic materials

Valorisation de déchets de caoutchouc dans les matériaux de construction : cas d’un composite cimentaire cellulaire

In this work, the idea is to use rubber waste particles as a raw material, to develop a new lightweight construction materials. The objective of the research reported in this paper is to investigate the physico-mechanical properties of Aerated Cement-Rubber Composites (ACRC), based on rubber particles. The volume content ratio of the rubber particles ranged from 0% to 50%. The aerated composite was produced using a new type of proteinic air-entraining agent, in accordance with a specific aerating process derived in the laboratory. The aerated composite was produced to be used in cellular concrete applications. Results from tests performed on fresh aerated composites have demonstrated many attractive properties, such as improved workability and a high stability of air bubbles within the matrix. A study conducted on hardened composite properties has indicated a significant reduction in sample unit weight, thereby resulting in a level of compressive strength. The composite satisfies the basic requirement of construction materials, and could be used for insulated load-bearing wall this study has also highlighted the effect of the proteinic air-entraining agent on the cementrubber interaction system, as regards the composite’s compressive strength. However, an examination of the composite’s water capillary absorption reveals that the addition of rubber particles tends to restrict water propagation and reduce water absorption; sorptivity values decrease with increasing rubber particles content.Cette étude concerne l’évaluation des propriétés du composite cellulaire ciment-caoutchouc, élaboré à base de poussières de caoutchouc pour des teneurs allant de 0 à 50 %. L’allégement a été effectué suivant un procédé d’allégement par moussage protéinique, mis au point au laboratoire, en vue de l’utilisation du composite dans le domaine d’application des bétons cellulaires. L’étude du composite à l’état frais a montré une amélioration de la maniabilité, avec une bonne stabilité des bulles d’air dans la matrice. L’étude du composite à l’état durci a montré une nette réduction de la masse volumique, avec des propriétés mécaniques compatibles avec l’utilisation en isolant porteur. L’effet de l’agent entraîneur d’air protéinique sur les liaisons matrice/caoutchouc dans la résistance du composite a été mis en évidence. L’étude de l’absorption par capillarité du composite a montré que l’ajout de poussières de caoutchouc réduit la sensibilité à l’eau du composite

Freeze/thaw protection of concrete with optimum rubber crumb content

This research looks at utilising an optimum quantity of rubber crumb as an air entraining ad-mixture in concrete, thus providing maximum freeze-thaw protection and maximum strength. Microscopic and chemical analysis was carried out on the rubber sample to investigate how rubber crumb entrains air and reacts with the surrounding concrete. The work contained two pilot studies that informed the main test methodology. The pilot studies examined the air content/compressive strength relationship (1) and freeze/thaw cycle durations (2). Pilot study 1 informed the main test program by identifying an optimum addition of rubber crumb to a concrete mix, which was found to be 0.6% by weight of concrete. The main test investigated the use of rubber crumb in providing freeze-thaw protection of a C40 concrete mix after 3 days of curing. A freeze-thaw test was carried out on three separate batches of concrete containing washed rubber crumb, unwashed rubber crumb and plain concrete respectively. It was found rubber crumb was effective in providing freeze/thaw protection in both cases. This work builds on recent work to identify the best practical solution for reducing waste and providing the maximum freeze/thaw protection for a cleaner production process

A Comparative Study of the Influence of Rubber Particle Size on the Ductility of Cement Concrete Based on Energy's Dissipation Method

International audienceThis research work aims to study the feasibility of a cement concrete incorporating rubber particles while respecting its fundamental properties, namely controlled air entrainment and concrete workability, with mechanical strengths sufficiently high to ensure the bearing capacity of the pavement structure. The main challenge is to combine all these conditions to comply with the technical requirements of pavement structure design, and this without any particular treatment of rubber particles to modify the characteristics of the cement concrete, thus inducing a real gain both on economically and ecologically. To do this, two concrete mixtures were prepared and compared: Concrete with a crumb rubber aggregate (CCRA) and concrete with ground tire rubber (CGTR). The experimentation results showed that CCRA is less efficient than CGTR. Nevertheless, despite a significant reduction in mechanical strength, both materials can satisfy the basic properties required for their use in pavement design. The results also highlighted the positive effect of rubber in improving the ductility of both concretes through an analysis of the hysteresis loops. However, due to its better compactness, CGTR has better mechanical properties than CCRA. \textcopyright International Journal of Sustainable Building Technology and Urban Development

Elaboration and characterization of clay-sand composite based on Juncus acutus fibers

International audienceThe study reported in this paper was undertaken to investigate the feasibility of lightweight construction materials, based on vegetable fibres. This innovative material consisted of mixture of natural clay (60%) and natural sand (40%) reinforced with different levels of fibers extracted from Jancus acutus ``Smar''. The fibers were used as partial replacement of sand in mixture by volume at: 0% (Control Specimen), 5%, 10%, and 20%. The objective of this work is to evaluate the physico-mechanical properties, through the examination of materials lightning, mechanical strengths (compressive and flexural). Due to the high hygroscopic nature of the vegetable fibers, the thermal conductivity of the composite materials was measured at both wet and dry state at different volumes of Juncus fibers replacement. Test-results have shown that the addition of 20% fibers decreased the composite bulk density from 1900 kg/m(3) to 1100 kg/m(3), which results in a high reduction of mechanical performances in terms of compressive and flexural strengths. The experimental investigation of thermal behaviour of this composite has shown that the increase of fibers volume leads to a significant decrease in thermal conductivity. For a composite containing 20% of fibers replacement, the dry thermal conductivity decreased from 0.902 W/m.K for control specimen (without fibers) to a value of 0.327 W/m.K. However, at wet state, the corresponding thermal conductivity decreased from 1.543 W/m.K to 0.361 W/m.K. Despite the decrease in mechanical strengths, the resulting composite can thus be considered as a promising candidate for use in thermal insulation material, because a conductivity of 0.350 W/m.K is generally considered as the worst acceptable value for insulating building material. (C) 2019 Elsevier Ltd. All rights reserved

DURABILITY OF NATURAL POZZOLAN-BASED MORTAR EXPOSED TO SULFATE ATTACK

Cement is a strategic commodity in the civil engineering for the construction of reinforced concrete structures. But its production generates around 5% of toxic gases such as CO2 responsible for environmental degradation. Furthermore, cement industry is a consumer sector of non-renewable energy. The use in the cement of natural additions is a solution to reduce the CO2 gas and the cost of production. The purpose of this work is the study of a sustainable building material: natural pozzolan Beni-saf (PNB) incorporated to mortars exposed to sulfate attack (5% Na2SO4). The loss of mass, monitoring the pH reading of each attack solution as well as specimens dimensions are different tests to study the durability of mortars made with 10, 20 and 30% of natural pozzolan. The result derived from this research is that pozzolan improves mortars resistance to sodium sulfate environment.</p