Publications Scientifiques

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Author: search.filters.author.Safi, BrahimSubject: search.filters.subject.Cement

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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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    Physico-mechanical properties and thermal behavior of firebrick-based mortars in superplasticizer presence
    (Elsevier, 2016) Saidi, Mohammed; Safi, Brahim; Benmounah, Abdelbaki; Megdoud, Nadjiba; Radi, Faiza
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    Effects of alkaline and alkaline-earth ions on the rheological behavior and zetametric study of two cement pastes (artificial cement portland-CEMI and cement resistant to the sulfates-CRS) with the polynaphthalene sulfonate (PNS)
    (2012) Kheribet, R.; Samar, M.; Benmounah, A.; Safi, Brahim; Said, M.
    The use of admixtures which tends to be generalized in the formulation of self-compacting concrete (SCC), requires taking into account the chemical co mposition of cement, particularly its content of SO 3 , which can inhibit or restrain the effect of these a dmixtures (superplasticizers). For more information of the compatibility problem of cement-superplasticize r, the rheological tests with a rheometer-AR2000 and measurements of zeta potential with a Zêtasiser -2000 were used in this study. In order to understand this phenomenon due to the presence of S O 3 in cement, we propose to evaluate the action of alkaline and alkaline-earth ions, incorporating different types of additions (K + , Na + , and Ca 2+ ) to the cement pastes. To achieve this, our work will conce rn the study of rheological properties and physical characteristics of the pastes obtained using two ty pes of cement (C1: Cement Resistant to the Sulfates (CRS) and C2: CEMI). This experiment will focus on two reports: Water/Cement ( W/C) = 0.30 for which the polynaphthalene sulfonate (PNS) is used as supe rplasticizer and W/C = 0.50 (without superplasticizer). The results show that the presen ce of sulfate leads to different rheological behavi ors which are function of sulfates and the cements used
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    Effect of the heat curing on strength development of self-compacting mortars containing calcined silt of dams and ground brick waste
    (2013) Safi, Brahim; Ghernouti, Y.; Rabehi, B.; Aboutaleb, Djamila
    The strength development of self-compacting mortars (SCM) containing calcined silt (CS) and ground brick waste (GWB) was investigated. The variables are the nature of addition (CS and GWB) in the binder and the heat curing at different temperatures (20 ºC and 60 ºC) at 7 and 14 days of curing. Two temperatures 20 and 60 ºC were applied to samples with intermediate levels (depending on the drying method applied to precast) for 18 hours in total. In this study, a Portland cement (CEMII), Calcined silt (750 ºC for 5 hours), ground waste brick, were used in the binders of SCM. The results show that the compressive strength to 14 days of mortars, increases with annealing (60 ºC) compared to that measured at 20 ºC. Also, values of compressive strength of mortars at 14 days that are close to those obtained without 28 days curing treatment. Indeed, a strength gain of about 20.5% and 27.3% was obtained respectively for the SCM with GWB and the SCM with CS. However, a small change in mass recorded for both types of mortars
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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