Browsing by Author "Safi, Brahim"

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    Annealing effect on copper-doped sodo-borate glasses (na2o-4b2o3)
    (2023) Aboutaleb, Djamila; Safi, Brahim
    The annealing effect of an alkalino-borate type glass below the softening temperature was investigated accord ing to the Na2O-B2O3 binary system. Doping of the samples was done by the introduction of copper oxide "CuO" according to different levels. The properties of elaborate glasses before and after annealing have been studied. DRX diffraction, optical spectroscopy and infrared analysis were used to complete this study. The obtained results show that the annealing heat treatment affects the structure of these glasses by redistributing the structural units, partially correcting the defects and reinforcing them of the structure. It has been noticed that the BO3 units are reformed again and the BO4 have decreased, which has led to an increase in the coefficient of thermal expansion, a decrease in the diffraction index and optical dispersion, a drop in mechanical prop erties, thermal conductivity and electrical permittivity.
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    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, Wafa
    The 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.
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    Behavior of mortars hydraulic and organic matrix in aggressive environments
    (2013) Saidi, Mohammed; Safi, Brahim; Samar, Mohamed Faouzi; Benmounah, A.; Hamiane, Messaoud
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    Caractérisation rhéologique des fluides de forage à base d’eau, en présence d’un inhibiteur de gonflement
    (2010) Safi, Brahim; Benmounah, A.; Gueciouer, Abderazak; Samar, Mohamed Faouzi
    L’objectif de ce travail sera la mise au point de formulations de fluides de forage à base d’eau, optimisées avec l’ajout d’un inhibiteur de gonflement, destiné pour le forage de la phase 8" 3/8. Pour ce, nous avons d’abord élaboré différents systèmes à base de chlorure de potassium (KCl) et de polymère (PHPA) qui diminueront le gonflement des argiles tout en respectant les exigences environnementales. Ensuite, nous avons étudié le comportement rhéologique (viscosité plastique et yield-value) de chaque élément de la formulation en les soumettant aux effets de la température, de la salinité et de l’alcalinité, avant d’aboutir enfin à la formulation finale qui sera soumise ensuite à des tests standards, selon les normes API. Les résultats obtenus montrent une diminution significative du gonflement et la formulation retenue présente des caractéristiques physico-chimiques satisfaisantes ainsi qu’un comportement rhéologique rhéofluidifiant proche du modèle de Hershel Bulkley
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    Comparative Life Cycle Assessment of Two Types of Truck Bumper Produced in the Algerian Auto Industry
    (Bio One, 2020) Kebbouche, Zahia; Tairi, Abdelaziz; Safi, Brahim
    Currently, the reduction of weight in automotive is a very important topic to reduce the air pollution. In this context, the purpose of the present paper is to analyze a real case study through a comparison of the environmental impacts between a conventional steel bumper and a polyester prototype. In the first part of this work, a door-to-door life-cycle assessment methodology was used throughout the study of the component manufacturing phase. The SIMAPRO7.0 software is used to evaluate the impacts of both bumpers on the environment and health. The second part is devoted to dust analysis from the polyester workshop. The obtained results have allowed us to show the company that its choice of steel substitution by the polyester is advantageous for certain impacts including the impact of climate change, but unfortunately there may be, given the working conditions of the polyester workshop, a transfer of impact, since we will end up with a risk of health (irritations, cancers) for the workers. LCA has proven to be a very useful tool for validating a redesigned automotive component from an environmental point of view; from this case study, several recommendations were made for the company to design environmentally friendly components , and ecodesign should be introduced into the company's procedures
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    Comparative study of biopolymers action on physico-chemical and rheological properties of water-based drilling muds
    (Chemical Publishing, 2014) Bentriou, Abdelhak; Fourar, Karim; Benmounah, Abdelbaki; Safi, Brahim
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    A comparative study of the creep behavior of laminated composites : effect of type of fiber and matrix
    (Academic Journals, 2017) Basaid, D.; Aribi, C.; Kari, J.; Benmounah, A.; Safi, Brahim
    This paper presents the effect of matrix type on creep behavior at 80% loads of ultimate tensile strength of two laminated composites at different fiber and matrix system. For this, two types of laminated composites were manufactured based on two types of fibers (carbon fabric and glass fabric) with different matrix systems EPOCAST 50-A1 (EP50-A), Epoxy STR (STR) and Epoxy INJ812 (INJ). The tensile and creep behavior of each laminated composite was studied in the same test conditions. A microstructural study was also investigated by SEM-microscopy on the morphology of composite specimens after creep rupture failures at 80% of applied load. The obtained results showed clearly the influence of matrix type used on the tensile and creep behavior of studied composites. Indeed, it was noted that no creep rupture failures were observed in short-term (less than 4 h) for INJ/Carbon composite at tensile creep tests at 80% loads of ultimate tensile strength. At the same ultimate tensile strength, EP50/Carbon composite showed a best creep behavior up to 30 h and had a creep modulus higher than other laminated composites. The observation of rupture facets of all composite samples showed clearly that the rupture will take place in the direction of loading, creating voids at the interface resin/fiber. These are observed based on the nature of the matrix used
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    Comparison of the properties of two types of concretes by non-destructive tests: influence of the geometry of the specimens
    (2019) Daoui, Abdelhakim; Safi, Brahim
    Most concrete properties are affected by cement and mechanical properties, and some of the durability properties of cement are determined by cement mortars. However, the applications of ultrasound (non-destructive testing) on the determination of the properties of cement mortars are quite limited whatever the method used. Therefore, the required dimensions of the samples as well as the different types of specimens and concrete have not yet been established for special concretes such as self-placing concretes. In this study, non-destructive testing by determination of ultrasonic pulse velocity (UPV) and destructive testing of two types of concretes (regular concrete and self-placing concretes) were determined with different different frequency transducers for different sample sizes and shapes and the relationships between UPV and various concrete properties were studied. As part of the experimental program, three different ultrasonic frequencies (54, 82 and 150 kHz) were used. To this end, mortar mixtures have been prepared with various water / cement ratios having a constant cement content of 450 kg / m3. Cubic, cylindrical and prismatic samples of different sizes were prepared from each mixture of the concretes studied. Keywords: Concretes, SCC, Scale effect; specimen geometry, Compression stress; crushing test; ultrasound
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    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 bearing
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    Development and structural study of cements containing additions of industrial waste
    (2010) Saidi, M.; Hamiane, M.; Safi, Brahim; Benmounah, A.
    Certain mineral additions exploit a very significant role the behavior and the ageing of the works in the corrosive conditions and one can use them like barriers against the aggressiveness and the phenomenon of corrosion of the concretes. Cements made up of additions can be recommended especially in massive works, the stoppings, maritime and underground constructions and in the cementing of the oil wells. The use of the adequate additions ensures the long-term stability and durability of the concretes of the underground, maritime works and the cementing of the oil wells… etc. To this end, within the framework of valorization of these additions (active and inert), in this study we were interested only in the study of the influence of incorporation of limestone, pozzolana, slag, tuff and dust electrostatic precipitator (crushed finely) like active addition in the matric E of cement, its effect on the behavior and ageing of cement S made up and on the microstructure of the concrete by a structural characterization by XRD
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    An ecological water‑based drilling mud (WBM) with low cost: substitution of polymers by wood wastes
    (Springer, 2019) Haider, Soumia; Messaoud‑Boureghda, Mohamed‑Zine; Aknouche, Hamid; Akkouche, Ali; Hammadi, Larbi; Safi, Brahim
    An ecologically friendly water-based drilling mud (WBM) was designed by using wood wastes (WP: wood powder) in order to substitute the organic polymers which are very expensive and often make the higher cost of the oil well drilling. This present work is dedicated on studying the rheological behavior and main rheological properties of WBM containing the wood powder at different contents and sizes by substitution of usually used polymers. The effect of wood powder on the drilling fluid filtrate was also analyzed. The drilling fluid that was developed has better rheological properties and fluid loss control which are required for a good functioning of oil well drilling. By a total substitution of polymers, the wood powder (300 μm at 850 kg/m3) can be used as a filtrate reducer of mud because the WBM filtrate obtained exhibits a minimum and having requested values for such formation
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    Effect of calcined silt on the rheological behavior of cement pastes of the self compacting concrete SCC
    (European Journals Inc, 2010) Safi, Brahim; Benmounah, Abdelbaki; Saidi, Mohammad Said; Aboutaleb, Djamila
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    Effect of Fiber Distribution on the Mechanical Behavior in Bending of Self-Compacting Mortars
    (Sciendo, 2020) Kheddache, Lynda; Chahour, Kahina; Safi, Brahim
    The purpose of this work is to assess the steel fiber distribution effect on physical and mechanical properties of self-compacting mortar. An experimental study was conducted to see the fiber distribution during the implementation of self-compacting mortars that are fluid and on mechanical behavior in bending tensile strength. A method of placing self-compacting mortar in the molds has been developed to highlight the distribution of fibers in the cementitious matrix. The mortars are placed in prismatic molds in three layers. The amount of steel fibers differs from one layer to another. A total quantity of 90 kg /m3 was distributed in prismatic molds of dimensions 40x40x160 mm3. Straight and hooked ends steel fibers were used. The characteristics of mortars containing both types of fibers in the fresh and hardened state were measured and compared to those of self-compacting mortar without fibers. The pouring by layer allowed us to deduce that the distribution of metallic fibers has a significant effect on the hardened properties of the mortar. Indeed, the mechanical strength of the fiber-reinforced mortar depends on the nature and distribution of fibers in the cementitious matrix (mortar). A gain in bending tensile strength of 71.83% was recorded for self-compacting mortars elaborated with hooked end fibers and 52.11% for those containing straight steel fibers. Indeed, mortars containing entirely the same dosage of steel fibers (90 kg/m3) have a bending tensile strength that varies according to the fibers dosage by layers. Mortar samples with higher fiber content in the lower layer have a higher bending tensile strength than other samples with a higher fiber layer in the middle or layer above. However, it should be noted that steel fibers with hooks are much more effective than those without hooks. Indeed, the effect of fiber distribution is more significant for fibers without hooks because the hooks can slow down the movement of the fibers during the pouring of the mortar. The variation of the dosages per layer generated a difference in the deflection values for the mortars. The deflection is much higher for fiber-reinforced mortars (with hooks) compared to fiber-reinforced mortars without hooks
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    Effect of isothermal heat treatment time on structural transformation and crystallization of B2O3-PbO glass
    (2008) Aboutaleb, Djamila; Iratni, A.; Safi, Brahim
    Lead borate glass was prepared by the quench method, followed by treatment at its isothermal temperature at different time periods. When the sample was rapidly cooled from the melt, it showed two distinguished opalescent layers. The SEM analysis and XRD pattern provide characteristics of glass without XRD peaks and their morphology show the aggregated spherical particles in the phase separated glass. This data show that phase separation occurred even when the melts were rapidly cooled, however, the sample shows a Ostwald ripen with increasing time of heat treatment, which implies that the size of particles increases and their number decreases. When changing the sample's composition by adding lead oxide (PbO), the sample crystallizes directly upon heat treatment. The infrared absorption spectra show shift edge for sample glass with heat treatment, which indicates a change of structural configuration, i.e. conversion of tetrahedral boron on triangular boron coordination
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    Effect of metakaolin as partially cement replacement on the compressive strength of standard mortars
    (2021) Amrane, Belaid; Souici, Khaled; Hami, Brahim; Kennouche, Salim; Safi, Brahim
    This study presents the effect of incorporating synthesized metakaolin on the compressive strength of standard mortars for a constant water/binder ratio of 0.5. Synthesized metakaolin mixtures with cement replacement of 5, 10, 15 and 20% were tested. From the results, it was observed that 15 % replacement level was the optimum level in terms of compressive strength. Beyond 15 % replacement levels, the strength was decreased but remained higher than the control mixture. Compressive strength of 52 MPa was achieved at 15 % replacement. This investigation has shown that it is possible to produce high strength mortars using local kaolin.
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    Effect of nanosilica-doped superplasticizer on the properties of cement mortars
    (STEF92 Technology, 2023) Safi, Brahim; Mechakra, Hamza; Saidi, Mohammed; Lecheb, Samir
    Recently, 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).
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    Effect of size and stacking of glass fibers on the mechanical properties of the fiber-reinforced-mortars (FRMs)
    (2011) Saidi, M.; Safi, Brahim; Benmounah, A.; Aribi, C.
    In modern day construction practice, repair and rehabilitation of structures have taken a prominent role. Indeed, the recent trend of rehabilitating and strengthening unreinforced masonry reinforced with glass fibers. In this paper, the use of fiber-reinforced-mortars (FRMs) is proposed for construction rehabilitation and reconstruction applications. A single type of fiber (glass fiber) with different length is considered; short, long and mixed. Several specimens mortars reinforced with fibers are tested in compression and flexure. Also, the stack and the microstructure of the interface glass fibers-matrix cementitious of the reinforced specimen, was examined. The results showed a remarkable increase in the mechanical resistances (50%), an important reduction of the brittleness of the reinforced mortars (lengthening higher than 40%) and a good ductility. That made it possible to increase considerably the safety of our constructions with a better esthetic aspect