Browsing by Author "Chaid, Rabah"

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    Assessment of the aggressive agents' penetration into concrete by non-destructive techniques
    (Emerald Publishing Limited, 2022) Khial, Nassima; Chaid, Rabah
    Purpose: Around the world, many structures are affected by pathological reactions between the concrete and the surrounding environment in which these structures are designed, these pathologies lead to compromise their serviceability. In this context, this paper aims to study the durability of concrete in different environments with non-destructive techniques, by studying its contamination by the aggressive agents’ penetration. And this, by evaluation of the influence of the durability indicator that is the absorption by immersion, on the mechanical properties (compressive strength, modulus of elasticity and damage), of specimens having undergone immersion/drying cycles, in different aggressive media (water, seawater and acids: sulfuric and acetic with a concentration of 5%). Design/methodology/approach: Concrete specimens were manufactured in the laboratory, and then underwent immersion/drying cycles, in parallel, the weight gain of the specimens was carried out in the wet state after immersion and in the dry state after drying, and the ultrasonic speeds were also taken in a dry state. The results showed a decrease in the mechanical properties studied, namely, the compressive strength as well as the elastic properties (modulus of elasticity, damage) as a function of the increase in absorption, and that the weakest properties are those of test specimens submerged in water. Findings: Non-destructive tests have shown that the parameters examined increase with the immersion/drying cycles, up to the fourth cycle. Beyond that, they drop gradually, and this is valid for four environments. This decline is due to the degradation of cement pastes exposed to water, seawater and acid attacks. This is explained by the greater or lesser dissolution of all the major elements making up the cementitious matrix (CSH, Ca(OH)2, CaO, SiO2, C3S, C2S, C3A, C2S) depending on the nature and concentration of the chemical substances evacuated. The results showed that the highest absorption rate and damage are those recorded for the specimen immersed in water, followed by that of the specimens immersed in acids, followed by that of the specimen immersed in sea water. The highest compressive strength and stiffness are those of the specimen immersed in sea water, followed by that immersed in acids, then in water. Originality/value: The work developed aimed to study the durability of concrete, by addressing the study of the coupling absorption – mechanical characteristics of concrete, in different aggressive media (water, seawater and acids), to seek a relationship between these parameters. The tests provided are non-destructive tests, which consist of taking measures that do not damage the concrete. They allow indirect measurements of the mechanical properties of concrete as well as the monitoring of their evolution over time. They also allow having certain accuracy, because the measurements are taken at the same place
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    Characterisation and microstructure of high-performance concretes reinforced with metal fibres ripened in seawater
    (Taylor & Francis, 2019) Boutiba, Aldjia; Chaid, Rabah; Molez, Laurent
    High-performance concretes reinforced with metal fibres (SFRHPC) have multiple advantages when they are used in the marine environment. These materials provide high strengths at the young age that permit faster formwork stripping, resistance to hydrostatic thrusts due to the tides, structural elements sections’ reduction, as well as weight reduction of the structure, and the increase of the abrasion resistance to sand or gravel. The maritime works are exposed to specific seawater aggressions. Seawater contains aggressive salts, which damage the concrete and the steel that it may contain. These salts are mainly chlorides and sulphates. This study investigated the ripening of steel fibre-reinforced high-performance concrete, with 15% substitution of cement by blast furnace slag, in Rance (France’s seawater). This experimental study analysed the effect of 6 and 24 months of ripening of the sample, in aggressive water, on the characterisation of the concrete and the microstructure of the cement’s matrix and its fibres. Also, in this study, after two years of concrete conservation, we carried out the chemical and mineralogical composition of the seawater. The results showed that there is no significant alteration of concrete kept in seawater and the steel fibres were not altered. In other words, it stayed passivated even after two years of ripening
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    Durability of high performance concrete in an aggressive environment
    (Trans Tech Publications, 2014) Merida, Ahcene; Kharchi, Fattoum; Chaid, Rabah
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    Effect of Slag on the Porosity and Microstructure of HPC Reinforced with Hybrid Steel Fiber
    (ISRES Publishing, 2023) Boutiba, Aldjia; Chaid, Rabah; Molez, Laurent
    Due to their structural and economic performance, high performance metal fiber concretes are increasingly used in construction, but with the addition of metal fibers, workability decreases as the amount of fibers added increases. In order to improve workability, a larger quantity of fines should be used than for ordinary concrete. The use of granulated slag reduces the amount of clinker needed to make cement. It is considered that granulated slag improves the workability of concrete. According to Manai, this is due to the very low rates of water adsorption by the granulated slag grains at the start of mixing. Also, the addition of granulated slag has a positive effect on the porosity, but also on the microstructure of the hydrates. These two characteristics are factors determining the compressive strength and durability of the cement paste. The aim of this study is to define the effect of blast furnace slag on the porosity and microstructure of high performance fibre-reinforced concrete. The results of SEM and DRX observation of the microstructure of the concrete samples show that the addition of ultra-fine granulated slag resulted in a relative improvement in porosity and microstructure.
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    Effet du chlorure de sodium sur la durabilité des BHP
    (2012) Chaid, Rabah; Jauberthie, Raoul; Abadlia, Mohamed Tahar
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    Experimental study on steel fibre reinforced self-compacting concrete incorporating high volume of marble powder
    (Taylor & Francis, 2014) Haddadou, Naima; Chaid, Rabah; Ghernouti, Youcef
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    Impact of the nature of fibers on the physicomechanical behavior and durability of cement matrices
    (Springer, 2021) Aboutair, Wafaa; Chaid, Rabah; Perrot, Arnaud
    In this paper, the strength of concrete prismatic and cylinders concrete and reinforced with steel and polypropylene fibers are presented. Also, hybrid fibers with crimped steel and polypropylene were used in concrete matrix to study its improvements in strength and durability properties. The steel, polypropylene, and hybrid consisting of polypropylene and steel (crimped) fibers of various proportions by volume of cement were used in concrete mixes. Besides cubes, cylinders of 160 mm diameter X 320 mm high of concrete were cast with steel fiber, polypropylene fiber, and hybrid fiber, respectively, by volume of cement. The water absorption test was conducted on 28 and 90 days, and the test results show that the addition of steel and polypropylene fibers to concrete exhibits better performance. The test results show that use of steel fiber-reinforced concrete improves compressive strength and split tensile strength. The durability of such concrete is also improved
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    Resistant to sulphate attack of high performance fibre concrete with the addition of slag
    (Stowarzyszenie Producentow Cementu, 2015) Boutiba, Aldjia; Chaid, Rabah; Molez, Laurent; Jauberthie, Raoul
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    Use of recycled plastic bag waste in the concrete
    (2014) Ghernouti, Youcef; Rabehi, Bahia; Safi, Brahim; Chaid, Rabah
    The aim of this study is to explore the possibility of re-cycling a plastic bag waste material (BBW) that is now produced in large quantities in the formulation of concrete as fine aggregate by substitution of a variable percentage of sand (10, 20, 30 and 40 %). The influence of the PBW on the fresh and hardened states properties of the concrete: workability, bulk density, ultrasonic pulse velocity testing, compressive and flexural strength of the different concretes, has been investigated and analyzed in comparison to the control concrete. The results showed that the use of PBW improves the workability and the density, reduces the compressive strength of concrete containing 10 and 20 % of waste by 10 to 24 % respectively, which have a mechanical strength acceptable for lightweight materials, remains always close to reference concrete (made without PBW). The results of this investigation consolidate the idea of the use of PBW in the field of construction, especially in the formulation of concrete