Browsing by Author "Ghernouti, Y."

Now showing 1 - 13 of 13

Comparative behavior under compression of concrete columns repaired by fiber reinforced polymer (FRP) jacketing and ultra high-performance fiber reinforced concrete (UHPFRC)
(Taylor & Francis, 2014) Rabehi, B.; Ghernouti, Y.; Li, Alex; Boumchedda, K.
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
Effectiveness of repair on damaged concrete columns by using fiber-reinforced polymer composite and increasing concrete section
(Sage, 2012) Ghernouti, Y.; Li, Alex; Rabehi, B.
This research is a contribution to work on strengthening and repair of reinforced concrete structures, it presents a comparative study between two methods of repairing damaged concrete with an experimental investigation on the behavior of specimens initially pre-damaged up to intense cracking, repaired by increased concrete section and by bonding a carbon fiber reinforced polymer. In our study, the concrete columns with square sections of (15 × 15) cm2 and a height of 30 cm are tested under uniaxial compression loading up the damage, these columns have been repaired, using both methods, they are tested again and their behavior has been studied. Based on the criterion of Mohr–Coulomb failure, a model was developed for each method to validate the different results obtained experimentally. The experimental results show that the method to repair damaged concrete by carbon fiber reinforced polymer has a good substrate adhesion, which offered a great improvement in strength and ductility compared to the method by increased concrete section. The experimental results have been compared with the theoretical models, a good correlation was obtained
Fresh and hardened properties of self-compacting concrete containing plastic bag waste fibers (WFSCC)
(Elsevier Ltd, 2015) Ghernouti, Y.; Rabehi, B.; Bouziani, T.; Ghezraoui, H.; Makhloufi, A.
This paper presents the fresh and hardened properties of self-compacting concrete (SCC) containing plastic bag waste fibers (PBWF). Fibers were prepared by recycling waste material such as, plastic bag. Fourteen mixtures of SCC with 0.40 of water/cement ratio were studied, twelve SCC mixtures with plastic bag waste fiber (WFSCC) by varying the length of fibers (2, 4 and 6 cm) with different levels of incorporation (1, 3, 5 and 7 kg/m3) and two other mixtures, one with 1 kg/m3 of polypropylene fibers (PFSCC) and another without fiber as reference (RSCC). Slump flow, L-box, and sieve stability were performed to assess the fresh properties of the prepared mixtures. Compressive strength, splitting tensile strength and flexural strength of the concrete were determined for the hardened properties Test results show that mixtures based on PBWF with a length of 2 cm, met the criteria of self-compactability (evaluated by slump flow diameter, L-box and sieve stability test) regardless of the fibers content. The obtained results are very interesting, suggesting a possible use of PBWF for structural reinforcement of SCC, the presence of this fibers in concrete delaying the location of microcracks. Although, the incorporation of PBWF has not a significant effect on the compressive and flexural strengths, it has a important effect on the split tensile strength value at 28 days. The improvement varies from 4% to 74%, it depends on the amount of fibers, and it is not affected by the length of PBWF
FRP-confined short concrete columns under compressive loading : experimental and modeling investigation
(Sage, 2011) Ghernouti, Y.; Rabehi, B.
This study introduces the results of an experimental investigation on the behavior of the circular columns of concrete under a load of axial compression, confined by an envelope of composite materials (carbon fiber and glass fiber). The composite used is a FRP glued in surface with epoxy resin. The specific objectives of this study are: verifying the applicability of this method of reinforcement of the columns to improve the behavior of concrete from the point of view strength and ductility, seeing the influence of composite materials type used, and confronting the experimental results acquired with different models developed on one hand and on the other hand with empirical formulas developed by other researches. Two models were developed to represent the structural behavior of the tested samples based on the calibration of the experimental results and criterion of Mohr—Coulomb failure. The validity of the results acquired numerically is based on a comparison with experimental results as well as with empirical formulas developed
Multiple confinements of concrete columns by various embedded composite grids
(2008) Ghernouti, Y.; Ait Tahar, K.
This study exhibits the experimental results of axial compression tests on concrete cylinders, circumferentially confined by the set-up of the composite grids arranged inside the cylinder, according to several combinations of circumscribed grids. The main aim is to verify the applicability of this method and then to quantify the contribution to strength improvement due to confinement as well as its influence on the rupture mode under axial compression. The test results of loading carried out on cylindrical concrete specimens, confined by alveolus composite grids arranged inside the section, show that it is possible to substantially increase the ductility of the columns, and in certain cases, their strength. It is also noted that the rupture of confined concrete is highly influenced by the presence of the grids depending on the configuration and the shape of the cells (rhombus or hexagonal) constituting the composite grid. The experimental results are compared with the theoretical model data
Recycling of brick and demolition concrete aggregates wastes in the self compacting concrete
(2017) Ghernouti, Y.; Rabehi, B.; Ziani, Nesrine; Tamazirt, S.
Strength and compressive behaviour of ultra high-performance fibre-reinforced concrete (UHPFRC) incorporating algerian calcined clays as pozzolanic materials and silica fume
(Taylor & Francis, 2013) Rabehi, B.; Ghernouti, Y.; Boumchedda, K.
This paper presents results of an experimental study which investigates the effect of four pozzolan additions made from various by-product materials on physical and mechanical properties of ultra-high performance fibre-reinforced concrete (UHPFRC) compared with the silica fume (SF): waste bricks (WB) and three types of metakaolin (MK) as calcined clays at 750 °C: calcined clay of Djbel Debbagh quality 3 (DD), calcined sludge incineration at the manufacture of paper (PS) and calcined silt of dams (SD) having median particle sizes less than 45 μm are used as addition. For each addition, five percentages of steel fibres (1, 1.5, 2, 2.5 and 3%) were used to improve the performance of concrete. The results suggest that the use of WB, PS and SD has no significant effect on the compressive strength as compared with SF concretes. Calcined clay DD can be used as pozzolanic materials in making UHPFRC. This MK competes with the SF, after 28 days of curing, the concrete containing 25% of DD and 2.5% steel fibre presents a compressive strength of 179 MPa compared with the concrete containing 25% of SF and 2.5% steel fibre, which presents strength of 183 MPa
Strength and durability of mortar made with plastics bag waste (MPBW)
(Springer, 2012) Ghernouti, Y.; Rabehi, B.
The aim of this study is to explore the possibility of re-cycling a waste material that is now produced in large quantities, while achieving an improvement of the mechanical properties and durability of the mortar. This study examines the mechanical properties and the durability parameters of mortars incorporating plastics bag wastes (PBW) as fine aggregate by substitution of a variable percentage of sand (10, 20, 30 and 40 %). The influence of the PBW on the, compressive and flexural strength, drying shrinkage, fire resistance, sulfuric acid attack and chloride diffusion coefficient of the different mortars, has been investigated and analyzed in comparison to the control mortar. The results showed that the use of PBW enabled to reduce by 18–23 % the compressive strength of mortars containing 10 and 20 % of waste respectively, which remains always close to the reference mortar (made without waste). The replacement of sand by PBW in mortar slows down the penetration of chloride ions, improves the behavior of mortars in acidic medium and improves the sensitivity to cracking. The results of this investigation consolidate the idea of the use of PBW in the field of construction
Study of calcined halloysite clay as pozzolanic material and its potential use in mortars
(2012) Rabehi, B.; Boumchedda, K.; Ghernouti, Y.
In this research, we will try to understand the mechanisms involved in the introduction of calcined clays in substitution for a portion of cement in the manufacture of mortars. This experimental work focuses on the recovery of a clay type haloysite quality three, from eastern Algeria. This clay comes from a region called Djbel Debbagh hence its name (DD3). The main objective of this study is to see the influence of the activated clay by calcination with different percentages of 5, 10, 15 and 20% in substitution of cement, on the physical-mechanical properties and behaviour of mortars towards chemical attacks. The study of pozzolanic activity allows to optimize a calcinations temperature of about 750°C, the study of its mechanical performance has shown an improvement of strength. Finaly the results of the durability test showed a good performance in different environments
Study of the acoustical and thermo-mechanical properties of dune and river sand concretes containing recycled plastic aggregates
(Elsevier Ltd, 2020) Boucedra, A.; Bederina, M.; Ghernouti, Y.
The main objective of this work is the development of a new sand concrete whose aggregates consist only of river (0/4 mm) or dune (0/63 mm) sand and recycled plastic aggregates (0/3.15 mm). The work has both ecological and economical interest, without forgetting the technological interest which can certain materials provide. Indeed, what is new in our case is the addition of plastic aggregates to sand concrete as well as the study of the acoustic properties of this material. Different compositions have been studied by replacing (in volume) the mineral sand with plastic aggregates. The envisaged proportions are: 0%, 25%, 50% and 75%. The work focused mainly on the study of the effect of the addition of plastic aggregates on the properties of the river sand concrete and dune sand concrete, such as the thermo-mechanical properties and microstructure, with particular emphasis on studying the acoustic properties. The results obtained showed that, although the compressive strength of the studied composites is slightly reduced, their qualities in thermal insulation and acoustics absorption are significantly improved. For substitutions of up 75%, the sound absorption coefficient and the noise reduction coefficient (NRCs) ranged between 0.15 and 0.6 and between 0.28 and 0.39 respectively. Based on the obtained results, the final product is a lightweight concrete which can be classified, according to ISO 11654, into the sound absorption classes D and E. It is able to integrate among the new building materials and to contribute to sustainable development, particularly in local construction (arid regions). In conclusion, the recycled plastic waste and the dune sand can be a suitable alternative to the classic building materials
Using the ground brik waste and the silt of dams in self-compacting concrete : effect on the physical and mechnical properties
(2013) Safi, Brahim; Aboutaleb, Djamila; Ghernouti, Y.; Rabehi, B.
Valorization of calcined kaolinitic clay used in high performance mortar
(Université Omar Telidji de Laghouat, 2020) Mansour, S. M.; Ghernouti, Y.; Chaid, R.
In this work, an experimental investigation was carried out to evaluate the potential of an industrial pozzolan, the metakaolin, on the behavior of mortar. The aim is to use metakaolin as a 10% partial replacement of cement. Its effect on the physico-mechanical properties of the mortar has been analyzed. The results show that the incorporation of metakaolin decreases the density of the dried mortar and increases that of the wet mortar but these remain lower than those of the control mortar. Moreover, thermal analysis ATD / ATG shows that in the heat flow curve appears two endothermic peaks which correspond to the loss of mass of the cement pastes. Heat flux of these pastes increases when metakaolin is used into the cement. In addition, metakaolin increases the compressive and flexural strengths of wet and dry mortars by approaching without exceeding those of the control mortar. The use of metakaolin as a cement substitution has shown its potential to be a pozzolanic material that can offer economic, environmental and technical benefits.