Sandwich composites impact and indentation behaviour study

In order to better exploit the natural cork available in Algeria, an experimental characterisation of a jute/epoxy–cork sandwich material to impact and indentation was undertaken. The aim of this work is to evaluate the impact energy and cork density influence over the sandwich plate damage behaviours by instrumented static and dynamic tests. The results show that the onset damage force, the maximum force and the damage size are influenced by the cork density and the impact energy. The sandwich material, with the heavy agglomerated cork having a density of 310 kg/m3 is characterised by a weaker energy dissipation capacity, by about 3.72% for impact test and 3.29% for indentation one, than the sandwich with lighter cork (160 kg/m3). This difference is an infusion process consequence. The infiltrated resin into the agglomerated cork pores changes the material local rigidity. Also, under impact loading the sandwich laminates dissipate 11% more energy than with the quasi-static indentation test

Air Pollution from Diesel Particles and Chronic Obstruction Pulmonary Disease - CT Scan Study

Health problems have been observed in rabbits at low DEP concentration. The subject (animal) showed signs of chronic obstruction pulmonary disease (COPD). CT scan of the biopsy reveals significant emphysematous lesions. DEP grain causes inflammation of lung tissues around sites of deposition. Observations of tissue after formalin fixation reveal brown spots around the points of impact. It also reveals the double organic and inorganic aspect of DEPs. The organic compounds dissolve through slow diffusion in the lung physiological fluid while the inorganic part is partly handled by macrophages (phagocytosis)

Evolution of durability and mechanical properties of ordinary portland cement concretes in sulphates attack

Concrete in sulphates environments often undergoes significant alterations that often have significant adverse results on its engineering properties. However, the choice of cement type is a very important factor for concrete exposed in aggressive environment. This research presents the effect of two types of cement on the mechanical and microstructure properties of ordinary concretes exposed in aggressive solution dosed with 5% of gypsum (Ca2SO4.2H2O). The tests studied in this experimental part were the compressive strength, flexural strength, thermogravimetry, mercury intrusion porosimetry and mass variations of the concrete. The results clearly show that the CEM I 42.5 is suitable for the formulation of concretes exposed to sulphate attack and their properties are better compared with the CEM II/A 42.5

IVème Séminaire National Matériaux, Procédés et Environnement FSI, Boumerdès 15 & 16 Mai 2012

195 p. ; ill. ; 25 c

Flexural fatigue failure of concrete reinforced with smooth and mixing hooked-end steel fibers

This paper presents an experimental study on flexural fatigue dynamic behavior of reinforced concrete. Steel fiber is used for the retrofitting and strengthening flexural members, by mixing short smooth steel fiber and hooked-end fiber. By using Vibrophore HFP 150, dynamic loading was scanned at a resonance frequency of 100 Hz. Our objective is to examine the behavior of a specimen of 7 × 7 × 28 by a three-point bending test under high-level stress until it fails. Important research has been conducted to investigate the static and fatigue behavior of reinforcement. It was strengthened initially using one fiber, then using other additives. However, this research is not adequate to examine the flexural fatigue behavior of specimens by mixing different shaped fibers at different percentages. A further improvement in composite concrete performance is observed by mixing two steel fibers under high-level stress. The results are in alignment with the fatigue life data using Weibull distribution

Complex di-hydrate calcium phosphate - glutaraldehyde : formulation mechanism

The di-hydrate calcium phosphate CaHPO4, H2O (DCPD) reacts with glutaraldehyde OCH – (CH2)3 – CHO (GL) in an aqueous solution to give the complex OCH – (CH2)3 – CH(OH) – O – PO3Ca (DCPD-GL). In the solution, the complex appears in the form of hydrates (enolic stabilized by intramolecular isomery d, e, f and as the corresponding carboxylic acid g). In the solid state it is the enolic form wich dominates (cis and trans

Élaboration et caractérisation mécanique d'un stratifié renforcé par des fibres naturelles (lin, sisal)

International audienc