Publications Scientifiques
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Item Synthesis of resin from Alfa stem to applied as an adhesive corrosion-resistant coating(Springer Nature link, 2025) Toubal, Sara; Aribi, Chouaib; Chentir, Imen; Safi, Brahim; Bouaissi, Aissa; Saidi, MohammedThe demand for eco-friendly alternatives to petrochemical-based phenolic resins has risen due to increasing concerns about climate change, environmental impact, and manufacturing costs. This study introduces a sustainable approach by partially replacing phenol with lignin, a natural polymer rich in phenolic groups, extracted from Alfa stems. Using the alkaline method, 50% of phenol was substituted with lignin to synthesize phenol–formaldehyde (PF) resins. The synthesized lignin–phenol– formaldehyde (LPF) resin was characterized to verify its chemical structure and physical properties. The resin demonstrated significant antioxidant and antibacterial activity, particularly against E. coli and P. aeruginosa gram-negative bacteria at a concentration of 20 mg/ml. Additionally, the lignin substitution provided notable advantages over conventional industrial resin formulations. The lignin’s properties closely influenced the formulation of the LPF resin, making it similar to the reference CPF resin. However, the lower intensity observed in the LPF resin suggests potential limitations in the methylol group formation compared to the CPF resin. The antioxidant activity of LPF resin has been effectiveness in preventing cor- rosion on steel surfaces. When applied as an anti-corrosion coating and compared to industrially used CPF resins, LPF resin demonstrates its efficacy in such applications. Also, it should be noted that the impedance modulus of the elaborated resin coating remained consistently low throughout the entire immersion period, indicating its stable performance.Item Mechanical characterization and impact resistance of a novel hybrid composite based on salvadora persica roots and glass fibers(University of Zielona Gora, 2024) Chetouh, Samir; Ameur, Toufik; Bouakba, Mustapha; Gaagaia, Djamel Edinne; Khalfi, M.; Safi, BrahimThe observation of fibers in salvadora persica roots inspired us to consider the idea of using them as reinforcement to create an innovative composite. The current work focuses on the volumetric mass density, extraction, molding, and mechanical testing of composites and hybrid composites made from salvadora persica roots and glass fibers reinforced with two types of polyester matrix, chosen due their characteristics suitable for use in different orientations. Various extraction and combination methods have been used to identify an optimal approach for obtaining fibers from salvadora persica roots, considering its chemical composition (hemicellulose, pectin, and lignin). In this investigation, the hand lay-up method was used to mold specimens with different geometries. The composite and hybrid composite were combined with a polyester matrix and subjected to various mechanical tests namely; tensile, impact resistance, and water absorption. The results indicate that reinforcing polyester resins with SP fibers, whether long or short, enhances the overall mechanical properties of the composite. Additionally, improved adhesion between salvadora persica roots fibers and resin was observed.Item Evaluation of Viscoelastic Performance and Molecular Structures of Natural Rubber/NBR Blends Reinforced by Carbon Black and Nano-Silica(Periodica Polytechnica, 2024) Chelli, Amel; Mechakra, Hamza; Chellil, Ahmed; Tria, Djalel Eddine; Bessa, Wissam; Ikkache, Kamel; Safi, BrahimThis study focuses on the evaluation of the dynamic mechanical properties, molecular structure, density, hardness, swelling behavior of natural rubber blends (NR) and nitrile rubber (NBR) reinforced with carbon black and/or nano-silica. An experimental work has been conducted to study of the effects of increasing NR content and incorporating nano-silica on the mechanical properties and molecular structure were studied using dynamic mechanical analysis (DMA) and Fourier transform infrared (FTIR) spectroscopy. The results show that increasing the NR content and/or incorporating nano-silica into the elastomer leads to a higher storage modulus with no significant change in the glass transition temperature. FTIR analysis indicates the compatibility of the polyblends and the presence of oxidation of the main polymer chain generated during the grinding of the rubber. Additionally, the results of the swelling study demonstrate that stronger molecular interactions occur on the surface of the nano-silica between the nitrile radicals in the NBR and the silanol (Si-OH) radicals. These findings suggest that blending NR and NBR with carbon black and/or nano-silica can improve the mechanical properties and compatibility of the resulting polyblends, with potential applications in the development of advanced elastomeric materials.Item RHEOLOGICAL AND MECHANICAL BEHAVIOR STUDY OF ECO-FRIENDLY CEMENT MORTAR MADE WITH MARBLE POWDER(University of Zielona Gora, 2024) Chahour, Kahina; Mechakra, Hamza; Safi, Brahim; Dehbi, Nacera-Melissa; Chaibet, CyliaThe work aim is to investigate the rheological and mechanical behavior of an eco-friendly mortar made with marble powder. Marble is have used as sand (total substitution of natural sand) and as an additional material (partial substitution of cement). Firstly, rheological tests were carried out on the cement pastes in order to study the effect of cement substitution by marble powder on the rheological behavior. Secondly, our study is devoted to evaluate the mechanical performances (flexural strength, compressive strength, mechanical behavior and ultrasonic pulse velocity) of a fluid mortar such as the case of the self-compacting mortars elaborated with the marble powder as an addition a material and as sand. The mechanical test results show that compressive strength and mechanical behavior of an ecological cement mortar made with marble waste as natural sand improved significantly. However, marble-based mortars with 100% of marble sand have given a mechanical strength similar to that obtained by control cement mortar (100% natural sand). It was also noted that it an ecological cement mortar made with 30% of marble powder as an addition a supplementary material can be obtained. This leads to a reduction in cement consumption and a reduction in CO2 gas emissions caused by cement production.Item Assessing the Utilization of Sawdust in Water-Based Drilling Fluid for Managing Fluid Loss and Enhancing Viscosity(Taylor & Francis, 2024) Ysbaa, Saadia; Safi, Brahim; Sid, Asma Nour El Houda; Mhadhbi, Mohsen; Essafi, WafaThe evaluation of the use of sawdust in drilling fluid formulation is covered in this study. The investigation focused on the physicochemical and rheological properties of water-based mud (WBM) drilling fluids that included four different dosages of sawdust. These properties included yield stress, plastic viscosity, rheological behavior, gel strength, filtration test (API filtrate; American Petroleum Institute), and pH. The sawdust was employed as a substitute for the polymers commonly used in water-based muds (WBMs) to serve either as a viscosifier or as a fluid loss controller. The current study set out to evaluate how sawdust (diameter ≤630 µm) affected the primary characteristics of the drilling muds. Sawdust was utilized in place of carboxymethyl cellulose polymer (CMC) as a viscosifier and polyanionic cellulose polymer (PAC) as a filtrate reducer at several dosages (0, 10, 20, 50, and 100 g/L). It was found that the sawdust dosage and its role had a significant impact on the rheological characteristics of the drilling fluids. At amounts between 20 and 50 g/L, the sawdust was added as a viscosifier to the drilling fluids under study, resulting in a significant improvement in their physicochemical and rheological parameters (yield stress, plastic viscosity, and gel strength). However, the drilling fluids showed extremely high rheological properties and a viscosity that can slow down fluid circulation in the well when 100 g/L of sawdust were used, totally substituting for the polymers.Item Experimental and numerical investigation of impact behavior in honeycomb sandwich composites(SAGE, 2024) Djellab, Amira; Chellil, Ahmed; Lecheb, Samir; Safi, Brahim; Mechakra, Hamza; Houari, Amin; Kebir, Hocine; Madani, KouiderThis paper presents an experimental and numerical study on the low-energy impact fatigue and bending behavior of sandwich panels reinforced with composite laminate glass and carbon fabric facesheets, supported by a honeycomb core made of Nomex. The crushing behavior of honeycomb sandwich specimens subjected to the impact test was compared and discussed. Our results indicate that the carbon composite facesheets have a significant effect on the impact, resulting in an increase in impact resistance and a 157.14% increase in crack depth in the elastic region compared to glass facesheets reinforcement. This increase serves as an indicator of the laminate's ability to resist damage initiation and impact fracture mechanisms. Also, an increasing in flexural strength about 45.72% was observed in carbon facesheets honeycomb specimens compared to glass facesheets reinforcement. Microscopic illustration of the damaged honeycomb sandwich specimens was conducted to evaluate the interfacial characteristics and describe the damage mechanics of the composite facesheets and core adhesion under the impact test. The numerical approach proves to be efficient in terms of accuracy and simplicity compared to existing methods for predicting the damage mechanisms of honeycomb sandwich structures. It was noted that results of numerical study show best agreements with experiment results and the model can be used to predict the low-energy impact fatigue.Item Physico-mechanical characterization of an ecological marble based- mortar(STEF92 Technology, 2023) Chahour, Kahina; Safi, BrahimDisposal of waste generated by the industries remains one of the major challenges to preserve the environment. Indeed, the use of industrial waste and by-products in construction is an important advantage to conserve natural resources. For this reason, several studies have focused on the use of marble waste in construction as recycled aggregate or fine powder. The work aim is to investigate the physical properties and mechanical behavior of eco-friendly mortar made with marble powder. The experimental study consists in studying the effect of cement substitution by marble powder (0%, 5% 10% and 20% wt.) on the fluidity and mechanical properties (Flexural strength, compressive strength and mechanical behavior) of elaborated mortars. The results show that it is possible to manufacture an ecological mortar having the good mechanical characteristics with marble powder and with local materials with the same basic components as a normal mortar and thus obtaining the same characteristics as those known internationally. The content amount of the marble powder as an addition to the cement is satisfactory to produce an ecological mortar with good resistance and better cement economy.Item Effect of nanosilica-doped superplasticizer on the properties of cement mortars(STEF92 Technology, 2023) Safi, Brahim; Mechakra, Hamza; Saidi, Mohammed; Lecheb, SamirRecently, nanotechnology has attracted a considerable scientific interest due the potential new uses of non-particles, which can improve the properties of cement mortars or concretes, such as Nanosilica. Nanoparticles, like those of nanosilica, have been shown to have unique physical and chemical properties different from those of conventional cement additions. Nanosilica was used either to replace part of the cements or as an addition to improve the performance of the cement such as accelerating the hydration of the cement phases. This work investigates the effect of nanosilica adding to superplasticizer on fresh and hardened properties of cement mortars. For this, three superplasticizer types of three different firms doped with nanosilica (NS) at 1.5% wt. of superplasticizer (SP) to estimate the effect of nanosilica-based superplasticizer on the properties of cement mortars in the fresh and hardened state. An experimental study was conducted to evaluate the three SP based on NS on fresh and hardened properties. Our results show that nanosilica is compatible with the three superplasticizer, what is remarkable on the mortars in the fresh state, with a good workability which is between (24cm and 28cm) and a total absence of segregation which acts on the mechanical properties of the self-consolidating mortar in (3,7 and 28 days).Item Crack growth diagnostic of ball bearing using vibration analysis(Sciendo, 2022) Belaid, S.; Lecheb, Samir; Chelil, A.; Mechakra, H.; Safi, Brahim; Kebir, H.It is known that supported ball bearings have great effects on the vibrations of the gear transmission system, above in all the presence of local faults as well as the crack growths. For this purpose, this paper focuses on shock and vibration crack growth diagnostic of ball bearing using vibration analysis. Our work is devoted first to a study the static behaviour of the ball bearing by determining the stress, strain and displacement, then its dynamic behaviour by determining the first four natural frequencies. Secondly, a dynamic analysis study of the bearing was carried with defects as a function of crack size and location. The obtained results clearly show that the natural frequencies decrease in a non-linear way with the growth of the length of the crack, on the other hand the stress increases with the presence of the singular points of the crack. Finally, this residual decrease in natural frequencies can be used as an indicator of the state of failure, as well as a parameter used for the diagnosis and screening, and to highlight the fatigue life of the bearingItem Rheological and Physic-mechanical study of metallurgical cements based on Nano-silica combined with blast furnace slag(Matrix Rom, 2020) Bouali, Khaled; Daoui, Hakim Mohammed; Safi, BrahimAceastă lucrare tratează comportamentul reologic și mecanic al cimenturilor metalurgice bazate pe nano-silice (NS) combinate cu zgură de furnal (GBFS). Un studiu experimental a fost realizat cu un raport constant de apă / liant (A / L) de 0,5 utilizat pentru toate mortarele studiate. Pentru a utiliza maximul GBFS și a scădea consumul de ciment, diferitele conținuturi (36% și 66% .wt) GBFS și 3% .wt de NS au fost alese și adăugate la Portland Cement (PC). Au fost efectuate teste reologice pe paste cimentate și au fost efectuate teste mecanice pe mortare elaborate cu ciment metalurgic studiat. Rezultatele obținute arată că pastele de ciment cu 3% NS fără GBFS au fost cele mai puțin vâscoase și au un efort de forfecare mai scăzut, cu o workabilitate acceptabilă în comparație cu alte paste de ciment. Cu toate acestea, în prezența GBFS, pastele de ciment devin mai vâscoase, ceea ce face ca debitul să fie mai dificil, cu o forță de forfecare mai mare la debit. De asemenea, rezultatele au arătat, în comparație cu mortarele de control GBFS, că încorporarea unei mici cantități de NS în ciment în prezența GBFS crește în mod remarcabil rezistența la compresiune la 28 și 90 de zile. Incorporarea a 3% în greutate NS în pastele de ciment cu un conținut de GBFS de 36% și 66% în greutate a dat valori ale rezistenței la compresie de foarte mare 90 zile (71,70 și 56,30 MPa). NS și LHF pot reduce în mod remarcabil porozitatea matricei de ciment și cresc densitatea acestuia, ceea ce explică de asemenea rezistența ridicată la rezistența la compresiune.