Publications Internationales

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    Optimizing Foam Concrete Performance Using Mixed Foaming Method: Impact of Mixing Speed, Mixing Duration, And Foam Dosage
    (South Florida Journal of Development, 2024) Galoul, Riadh; Boumchedda, Khaled; Mebtouche, Farouk
    Foamed concrete has gained significant attention, especially in the field of thermal insulation and acoustic insulation. However, all production methods are based on the pre-foaming method, while the mixed foaming method is an infrequent approach that should be considered and could be challenging. For this reason, this paper attempt to highlight this method and valuate it on par with the pre-foaming method in the production of foamed concrete, both in terms of structure and performance. These performances are directly dependent on the pore structure of this material (pore size, porosity rate, and pore distribution). Therefore, a process has been developed for sample preparation to achieve a final product with a well-controlled size and distribution of porosity, meeting the desired performance criteria. This process involves varying the following parameters: mixing speed (from 400 to 1000 rpm), mixing time (from 2 to 12 minutes), and the dosage of foaming agent (from 0.05 to 0.2%). The effect of mixing speed, mixing duration and the dosage of the foaming agent on the generated foam rate, density, structure at the millimeter scale, structure at the micrometer scale, and thermal conductivity was demonstrated. The obtained results show that with a generated foam rate extending to 79%, a density reaching 428 kg/m3, and a thermal conductivity achieving 0.181 w/k.m, the mixed foaming method becomes an important and competitive approach to the pre- foaming method in the production of foamed concrete.
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    Warping and porosity effects on the mechanical response of FG-Beams on non-homogeneous foundations via a Quasi-3D HSDT
    (Techno-Press, 2024) Nebab, Mokhtar; Atmane, Hassen Ait; Bennai, Riadh; Dahmane, Mouloud
    This paper suggests an analytical approach to investigate the free vibration and stability of functionally graded (FG) beams with both perfect and imperfect characteristics using a quasi-3D higher-order shear deformation theory (HSDT) with stretching effect. The study specifically focuses on FG beams resting on variable elastic foundations. In contrast to other shear deformation theories, this particular theory employs only four unknown functions instead of five. Moreover, this theory satisfies the boundary conditions of zero tension on the beam surfaces and facilitates hyperbolic distributions of transverse shear stresses without the necessity of shear correction factors. The elastic medium in consideration assumes the presence of two parameters, specifically Winkler-Pasternak foundations. The Winkler parameter exhibits variable variations in the longitudinal direction, including linear, parabolic, sinusoidal, cosine, exponential, and uniform, while the Pasternak parameter remains constant. The effective material characteristics of the functionally graded (FG) beam are assumed to follow a straightforward power-law distribution along the thickness direction. Additionally, the investigation of porosity includes the consideration of four different types of porosity distribution patterns, allowing for a comprehensive examination of its influence on the behavior of the beam. Using the virtual work principle, equations of motion are derived and solved analytically using Navier's method for simply supported FG beams. The accuracy is verified through comparisons with literature results. Parametric studies explore the impact of different parameters on free vibration and buckling behavior, demonstrating the theory's correctness and simplicity.
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    Investigation of the behavior of an RC beam strengthened by external bonding of a porous P-FGM and E-FGM plate in terms of interface stresses
    (Techno Press, 2023) Sadoun, Zahira; Bennai, Riadh; Nebab, Mokhtar; Dahmane, Mouloud; Atmane, Hassen Ait
    During the design phase, it is crucial to determine the interface stresses between the reinforcing plate and the concrete base in order to predict plate end separation failures. In this work, a simple theoretical study of interface shear stresses in beams reinforced with P-FGM and E-FGM plates subjected to an arbitrarily positioned point load, or two symmetrical point loads, was presented using the linear elastic theory. The presence of pores in the reinforcing plate distributed in several forms was also taken into account. For this purpose, we analyze the effects of porosity and its distribution shape on the interracial normal and shear stresses of an FGM beam reinforced with an FRP plate under different types of load. Comparisons of the proposed model with existing analytical solutions in the literature confirm the feasibility and accuracy of this new approach. The influence of different parameters on the interfacial behavior of reinforced concrete beams reinforced with functionally graded porous plates is further examined in this parametric study using the proposed model. From the results obtained in this study, we can say that interface stress is significantly affected by several factors, including the pores present in the reinforcing plate and their distribution shape. Additionally, we can conclude from this study that reinforcement systems with composite plates are very effective in improving the flexural response of reinforced RC beams.
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    The significant effect of K+ counterion in the enhancement of physicochemical and structural properties of amorphous aluminosilicates xerogels used as catalysts in the transesterification of waste frying oils
    (Taylor & Francis, 2023) Boufellah, Nassima; Aksas, Hammouche
    With the aim of better directing the polycondensation of oligomers during the synthesis of amorphous aluminosilicate xerogels by the sol-gel process using Na2SiO3, we reinforced the sols with Kþ counterion and studied its effect on the physicochemical and structural properties of the xerogels using XRD, FTIR, N2 physisorption, SEM, EDX, and TGA techniques as well as quantitative analysis of the acid sites by N-butylamine adsorption followed by potentiometric titration. Based on the results, the introduction of Kþ generated xerogels with good porosity and conferred resist- ance to matrix cracking. The amorphous character of the xerogels did not change after adding Kþ. FTIR spectra showed that the composition of the xerogels was improved after the addition of Kþ. Cation exchange and sulfur removal were much more efficient in the presence of Kþ which improved the acidity of the xerogels. The best percentages of Si and Al were observed at the Naþ/Kþ ratios of 4 and 1.The enhanced xerogel prepared with Naþ/Kþ ratio of 1 gave a biodiesel yield of 80.44% at the optimum parameters and was used for three reaction cycles without signifi- cant loss of biodiesel yield.
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    Carbonate reservoir quality variations in basins with a variable sediment influx : a case study from the balkassar oil field, potwar, Pakistan
    (American Chemical Society, 2022) Muhammad Raiees, Amjad; Muhsan, Ehsan; Muyyassar, Hussain; Al-Ansari, Nadhir; Abdul, Rehman; Zohaib, Naseer; Muhammad Nauman, Ejaz; Baouche, Rafik; Elbeltagi, Ahmed
    The carbonate reservoir quality is strongly reliant on the compaction process during sediment burial and other processes such as cementation and dissolution. Porosity and pore pressure are the two main factors directly affected by mechanical and chemical compactions. Porosity reduction in these carbonates is critically dependent on the overburden stress and subsidence rate. A variable sediment influx in younger basins may lead to changes in the reservoir quality in response to increasing lithostatic pressure. Deposition of molasse sediments as a result of the Himalayan orogeny caused variations in the sedimentation influx in the Potwar Basin of Pakistan throughout the Neogene times. The basic idea of this study is to analyze the carbonate reservoir quality variations induced by the compaction and variable sediment influx. The Sakesar Limestone of the Eocene age, one of the proven carbonate reservoirs in the Potwar Basin, shows significant changes in the reservoir quality, specifically in terms of porosity and pressure. A 3D seismic cube (10 km2) and three wells of the Balkassar field are used for this analysis. To determine the vertical and lateral changes of porosity in the Balkassar area, porosity is computed from both the log and seismic data. The results of both the data sets indicate 2-4% porosities in the Sakesar Limestone. The porosity reduction rate with respect to the lithostatic pressure computed with the help of geohistory analysis represents a sharp decrease in porosity values during the Miocene times. Pore pressure predictions in the Balkassar OXY 01 well indicate underpressure conditions in the Sakesar Limestone. The Eocene limestones deposited before the collision of the Indian plate had enough time for fluid expulsion and show underpressure conditions with high porosities
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    Study of vibratory behavior of interconnected porous PZT by impulse method
    (2010) Boumchedda, K.; Ayadi, A.; Aouaroun, T.; Fantozzi, G.
    Performances in ultrasonic active transducers of interconnected porous lead zirconate titanate (PZT) piezoelectric disks with a porosity ranging from 30 to 70%, and polarized along their axial axis, are investigated. The characterization method used is based on the measurement of the voltage, which appears between the two faces of the piezoelectric element when it is excited by a current impulse. The device used, allows the acquisition of axial and radial vibrations of the transducer, and from these data, electromechanical and acoustic parameters are deduced. One observes that interconnected porosity causes the disappearance of the radial vibrations, and for large porosities the disk vibrates exclusively according to the axial mode. kt is increased, the acoustic impedance is reduced, and the axial propagation velocity reaches ∼2500 m s−1 for 30% of porosity. These results show that interconnected porous PZT are suitable for making ultrasonic active transducer, such as biomedical imaging devices
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    Properties of a hydrophone produced with porous PZT ceramic
    (2007) Boumchedda, K.; Hamadi, M.; Fantozzi, G.
    Interconnected piezoelectric porous ceramics PZT have been tested for possible use in hydrophone applications. These materials consisted of: (1) ceramics with fine porosity having pores from 50 to 100 μm and (2) cellular ceramics having cavities of the order of the millimeters. Porous ceramics are coated with flexible polymer standard polyurethane for the hydrostatics tests. The effect of the size of the pores and porous volume on the sensitivity of the sensor is studied and the performances of the hydrophones devices are presented