This paper presents preliminary study results on the use of local natural pozzolan (NP) as a mineral addition. The natural pozzolan was obtained from a source in north-western Algeria and was composed of zeolite and plagioclase, which are mineralogical materials containing large quantities of SiO 2 and Al 2 O 3 . A number of cements were prepared in which portland cement (OPC) was replaced by NP in the range of 0-25%. The parameters investigated included pozzolanic activity, setting times, heat of hydration, compressive strength, and the crystalline hydration products (by XRD).The pozzolanic activity index was evaluated on the basis of physical and mechanical parameters (standards ASTM C618 and ASTM C311) and through a chemical analysis (European standard . The performance of natural pozzolan cement exposed to aggressive solutions (sulphuric and nitric acids) and their resistance to chloride permeability were also analysed.Cet article présente des résultats d'études préliminaires sur l'utilisation d'une pouzzolane naturelle locale (NP) comme addition minérale. Cette Pouzzolane naturelle provient de la region nord-Ouest d'Algérie. Elle est composée de zeolite et plagioclase qui sont des matériaux minéralogiques contenant de grandes quantités de SiO 2 et Al 2 O 3 . Des mortiers ont été préparés dans lesquels le ciment Portland (OPC) est remplacé par la pouzzolane naturelle dans des proportions variants de 0 -25%. Les paramètres recherchés sont l'activité pouzzolanique, le temps de prise, la chaleur d'hydratation, les proprieties mécaniques. L'indice de l'activité pouzzolanique a été évalué sur la base des paramètres physiques et mécaniques (normes ASTM C618 et ASTM C311) et par une analyse chimique (norme européenne NF EN 196-5). La performance de ces mortiers exposés à des solutions agressives (acides sulfuriques et nitriques) et leur résistance à la perméabilité des chlorures furent aussi analysées.
Researches into new and innovative uses of waste plastic materials are continuously advancing. These research efforts try to match society's need for safe and economic disposal of waste materials. The use of recycled plastic aggregates saves natural resources and dumping spaces, and helps to maintain a clean environment. The present articles deals with the resistance to chemical attack of polymer-mortars, which are often used as low-cost promising materials for preventing or repairing various reinforced concrete structures. To gain more knowledge on the efficiency of polymer-mortar composites, four mortar mixtures: one specimen with Portland cement and three mixtures with 2.5, 5, and 7.5 wt% of the substitution of cement by polyethylene terephthalate (PET) were exposed to the influence of aggressive environment (0.5%, 1% and 1.5% HCl acids, 10% NH 4 Cl, 5% H 2 SO 4 acid and 10% (NH 4) 2 SO 4 solutions). The measurements of several properties were carried out, the results were analyzed and the combination of X-ray diffraction, FT-IR spectroscopy, differential thermal analysis (DTA), thermogravimetric (TG) analysis, differential scanning calorimetry (DSC) analysis and the composites were also observed by SEM led to the positive identification of the deterioration products' formation. From this study, it was found that the addition of PET to the modified mortars, means reducing the penetration of aggressive agents. So, the PET-modified mortars exposed to aggressive environments showed better resistance to chemical attack. The new composites appear to offer an attractive low-cost material with consistent properties. The present study highlights the capabilities of the different methods for the analysis of composites and opened new way for the recycling of PET in polymer-mortars.
In recent years, the rapid deterioration of various reinforced concrete structures has been a widely recognized problem in the world. Penetration of chloride ions into the concrete structures was found to be the major cause of premature corrosion of reinforcing steel and to promote their deterioration. The present articles deals with the resistance to chloride penetration of polymer-mortar, which are often used as low-cost promising materials for preventing or repairing various reinforced concrete structures. To gain more knowledge on the efficiency of polymer-mortar, four mortar mixtures: one specimen with Portland cement (control sample) and three mixtures with 2.5, 5, and 7.5 wt % of the replacement of cement by polyethylene terephthalate (PET) were tested for chloride ion permeability under immersion in 5% sodium chloride solution. Their chloride ion penetration behavior is discussed by applying Fick's second law. In conclusion, the chloride ion penetration depth and apparent chloride ion diffusion coefficient of the polymer-mortar composites are smaller than those of unmodified mortar.
Plastic industry produces large amounts of waste polyethylene terephthalate (WPET), what causes environmental problems. An investigation was carried out on the effect of sulfate attack on the durability of composites produced with WPET. An attempt was also made to determine the thermal coefficients as well as the dynamic elastic moduli. Experiments were accomplished on limestone sand and cement mortars where the blended Portland cement was partially replaced by various volume fractions of WPET particles. The test solutions used to supply the sulfate ions and cations were 5% sodium sulfate solution and 5% magnesium sulfate solution. Tap water was used as the reference solution. Mass changes, compressive and flexion strengths measured on specimens were used to assess the changes in the mechanical properties of composites exposed to sulfate attack at different times. X-ray diffraction, FT-IR spectroscopy, scanning electron microscope (SEM/EDS) and differential scanning calorimetry were used to evaluate the microstructural nature of the sulfate attack. The test results showed that the presence of WPET had a beneficial effect in the control of the strength loss due to sodium and magnesium sulfate attacks and gave better insulation properties. This study insures that reusing TWPET particles as cement substitutes in mortar gives a good approach to sulfate durability, insulation, mechanical properties and solves some of the solid waste problems posed by plastics. Therefore, WPET-mortar composites are often presented as the materials of the future because of their potential for innovation and the advantages they offer. In fact, using WPETs as cement substitutes reduces the energy consumption. These composites address problems related to environmental pollution by CO2 emissions, and are used to repair various reinforced concrete structures.
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