Mohamed Mouli

Evaluation of natural pozzolan for use as supplementary cementitious material

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 SiO2 and Al2O3. 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 NF EN 196-5). 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 SiO2 et Al2O3. 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.

Application of Polymer-Mortar Composites as a Sustainable Building Material

In a number of countries, important research projects are nowadays carried out and are mainly devoted to developing original approaches to sustainability in order to improve the lifetime of reinforced concrete structures. This paper describes an innovative use of plastic bottle waste as cement-substitution within composite materials for preventing chemical attacks, energy efficiency in buildings or repairing various reinforced concrete structures. So, experiments were accomplished on polymer-mortar composite materials where the cement was partially replaced by various volume fractions of waste polyethylene terephthalate (PET) particles (0%, 6%, 12% and 17%). The specimens were tested by destructive and non-destructive testing and for chemical resistance to acid solutions at different concentrations. From this study, it was found that the PET-modified mortars exposed to aggressive environments showed better resistance to chemical attack than unmodified one without substantially affecting the mechanical strength in tap water and UPV values decrease as the proportion of PET waste in the mix increases. The addition of PET to the modified mortars, means reducing the penetration of aggressive agents. The formations which appear such as different calcium salts were determined by TG/dTG analysis. So, these composite materials are often used as low-cost materials for energy efficiency in buildings, preventing chemical attacks or repairing various reinforced concrete structures exposed to aggressive environments where high resistance to acid is required and to both reduce sound intensity and dampen vibrations.

A Study of Natural Pozzolan Mortars Exposed to Chlorides as a Sustainable Building Material

Reinforcement corrosion is caused either by chloride ions or carbonation, although chloride-induced reinforcement corrosion is the most widespread and serious problem. Moreover, the use of supplementary cementitious materials has been proposed in order to mitigate the durability problem, reduce the production costs and control the emission of greenhouse gases (GHGs). This paper reports the results of a study conducted to investigate the influence of Algerian natural pozzolan on reinforcement corrosion in blended cement mortars exposed to chlorides. Compositions, with replacement levels of 0, 10, 20 and 30% of normal Portland cement by mass of cement by natural pozzolan, were investigated. The exposure solution contained a fixed concentration of 5% sodium chloride. The compressive strength, corrosion potential, corrosion current density, sorptivity, rapid chloride ion penetration, in accordance with the standard ASTM C1202-12, were determined in order to characterize the mechanical and electrochemical behavior of the mortars. It was found that the use of natural pozzolan had resulted in a significant decrease in the corrosion rate of rebars, better mechanical performances and also a resistance to penetration of chlorides ions.