ANTI-BACTERIAL EFFECTS OF GLYCOSIDES EXTRACT OF GLYCYRRHIZA GLABRA L. FROM THE REGION OF DJAMÂA (SOUTH-EAST OF ALGERIA)

The natural extracts of plants contain a variety of biologically active molecules. In this context, we attempted to evaluate the antimicrobial activity of some extracts prepared from the root of Glycyrrhiza glabra L., which grows in the region of Djamâa (south of Algeria). The qualitative analysis of these extracts revealed the presence of plant glycosides, which is confirmed by a quantitative analysis based on the detection test of glycosides, who demonstrated that the extracts are rich in these molecules, where the content of glycoside reached (10 %) for the ethanol extraction. The evaluation of the glycoside extract antimicrobial activity revealed a strong effect of inhibition on different strain of bacteria, when it was responsible for a large zone of inhibition of the bacterial strain Pseudomonas aeruginosa, compared to Escherichia coli and staphylococcus aureus. From these results, we can say that the glycoside extracts have different antibacterial effects depending on the species

EFFET DE LA TENEUR EN FIBRES DE PALMIER DATTIER ET DE LA CONTRAINTE DE COMPACTAGE SUR LES PROPRIÉTÉS DES BLOCS DE TERRE COMPRIMÉE

Afin de valoriser les matériaux locaux, de contribuer à la réduction des coûts de construction et de l’énergie consommée pour le chauffage ou la climatisation, des fibres de surface du palmier dattier mâle (FSPDM) ont été utilisées pour stabiliser les blocs de terre comprimée (BTC). L'objectif principal de ce travail est l'étude de l'effet de la teneur en fibres de palmier dattier et de la contrainte de compactage sur les propriétés mécaniques du BTC renforcée par ces fibres. L'étude s’est focalisée aussi sur sa sensibilité à l'eau, en étudiant son absorption totale. Dans ce cadre, on a utilisé trois teneurs en ciments (5, 6.5 et 8 %), quatre teneurs en fibres (0.05, 0.1, 0.15 et 0.2 %) du poids du mélange sec et trois contraintes de compactage (1.5, 5 et 10 MPa). Les résultats indiquent qu’il y a une amélioration de la résistance à la compression sèche des blocs avec 0,05% en fibres, 8 % en ciment et une contrainte de compactage de 10 MPa. Mais pour le reste des cas étudiés, l'ajout de fibres a un effet négatif sur les propriétés du BTC. Cette étude a montré aussi que l’augmentation de la contrainte de compactage conduit à l’amélioration de la résistance à la compression sèche In order to valorise locals materials, to contribute to the reduction of construction costs and energy consumed for heating or conditioning, the male date palm surface fibers (MDPSF) have been used to stabilize the compressed earth blocks (CEB). The main objective of this work is the study of the effect of date palm fibers content and compaction pressure on the mechanical properties of CEB reinforced with this fibers. The study also focused on its sensitivity to water, by studying its total absorption. In this framework, three cement contents (5%, 6.5% and 8%), four fibres contents (0.05%, 0.10%, 0.15% and 0.20%) of the weight of the dry mixture are used, and compacted the soil with a static loading by applying three compacting stresses (1.50 MPa,5 MPa and 10 MPa). The results indicate that, an improvement in dry compressive strength of the blocks with 0.05% fibres content and 8% cement content and compacted at 10MPa pressure, is recorded. But for the remaining cases studied, the addition of fibers has an adverse effect on the properties of CEB. This study also showed that the increase in compaction stress leads to the improvement of dry compressive strengt

Bamboo reinforced concrete: a critical review

© 2018, The Author(s). The use of small diameter whole-culm (bars) and/or split bamboo (a.k.a. splints or round strips) has often been proposed as an alternative to relatively expensive reinforcing steel in reinforced concrete. The motivation for such replacement is typically cost—bamboo is readily available in many tropical and sub-tropical locations, whereas steel reinforcement is relatively more expensive—and more recently, the drive to find more sustainable alternatives in the construction industry. This review addresses such ‘bamboo-reinforced concrete’ and assesses its structural and environmental performance as an alternative to steel reinforced concrete. A prototype three bay portal frame, that would not be uncommon in regions of the world where bamboo-reinforced concrete may be considered, is used to illustrate bamboo reinforced concrete design and as a basis for a life cycle assessment of the same. The authors conclude that, although bamboo is a material with extraordinary mechanical properties, its use in bamboo-reinforced concrete is an ill-considered concept, having significant durability, strength and stiffness issues, and does not meet the environmentally friendly credentials often attributed to it

Characterization of Date Palm Wood Used as Composites Reinforcement

This work reports the results of an experimental investigation on physical and mechanical properties of Algerian date palm tree residues in order to optimize their performances when used as reinforcement. The results have shown that all the samples are characterized by porous and fibrous structure with irregular surface, which contains a large number of uncompleted grown fibers (expected to be residual lignin). Concerning the mechanical properties of date palm fibers (DPF), the results show that they are comparable to those reported for coir and are lower than those reported for other natural fibers. However with regard to the specific mechanical properties, date palm fibers show higher values than those of other natural fibers. This is due to the low values of bulk density of date palm wood, especially of that of Petiole

Modèle analytique pour les assemblages mixtes soumis à moment positif

Nowadays, modern codes and standards such as the (Eurocode 4, 2004) deal with the characterisation of steel–concrete composite joints in building structures, mainly under hogging bending moments in the beam. However, in sway composite frames or when the composite structure is subjected to an accidental/exceptional event such as earthquake or column loss, the beam-to-column joint may be subjected to sagging bending moment, a loading situation which is not yet covered by the codes. This paper deals with the behaviour of composite beam-to-column external joints under sagging bending moments, mainly focusing on the specific joint component “concrete slab in compression”. Indeed, if reference is made to Eurocodes, the method recommended to characterise structural joints is the component method and the “concrete slab in compression” component has been identified as the missing component to be able to apply this method to composite joints subjected to sagging bending moment. In this article, the finite element method is used to model the slab using VecTor 2 software. Through the performed numerical simulations, the behaviour of the slab is studied in detail and an analytical model is proposed. With the proposed model, it is possible to characterise the concrete slab in compression component and so, to apply the component method to predict the mechanical properties of composite joints subjected to sagging bending moment