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The durability of reinforced concrete structures, built on the seafront, has been at the heart of recent concerns. Indeed, chloride transport across the porosity of concrete coating produces medium to long-term corrosion of reinforcements. This has a direct impact on the mechanical behavior and the ageing of the affected structures. The difficulty of in situ monitoring of these structures, continuously and non-destructively against infiltration of chlorides, is still topical. The work presented here aims mainly at correlating the electrical properties, i.e. electrical resistance, conductivity…, with the physical characteristics (porosity, tortuosity, ...), of granular materials using Archie's law. The recommended experimental program consists in placing, different granular materials, i.e. sand, mortar, bricks, and concretes saturated with electrolytic solutions, in a PVC cell fitted with a pair of stainless steel electrodes connected to an electrical circuit, in order to measure the electrical resistances. The results obtained allow one to determine durability factors, such as the connected porosity and the coefficient of chloride diffusion through a simple measurement of the EC, and estimate the tortuosity parameter that governs transport in porous media.

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This is a hydraulic and geochemical study on 2 materials: natural clay (AN) and a regenerated material made up of a sand-bentonite (SB) mixture. The hydraulic part allowed us to conclude that a 10% industrial bentonite content mixed with sand offers hydraulic properties that are similar to those of AN material and are lower than the required standards. The geochemical properties of both AN and SB matrixes are comparable with those of some of the synthetic leachates studied. Furthermore, the Langmuir model helped us to identify the adsorption capacities of both matrixes with the following selectivities: Pb > Cu > Cd > Zn.

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The study of the corrosion inhibition of armatures made of steel conceived for reinforced concrete by sodium phosphate is the aim object of our experimental tests. Gravimetric and electrochemical measurements were carried in three different Mediums contaminated by chlorides (3% NaCl) with addition of increasing concentrations of sodium phosphate. Inhibitory efficiency reached 80% at an optimal concentration of 7,5 × 10 -3 M, the results obtained using the gravimetric measurements are in good agreement with those obtained by electrochemical methods. However, the monitoring of the pH evolution after 24h shows in the three studied environments, that the pH decreases slightly at 24 hours from the initial pH at t 0 , due to the presence of corrosion products which change the state of the final solution. Also, scanning electron microscopy revealed the existence of layers of apatite on the metal surface previously treated with the sodium phosphate which confirms the formation of a protective film around the surface of the metal.

In this paper, an experimental study describing the coupling between temperature and external sulphate attacks on cementitious materials is performed. Cubic mortar specimens made of three types of cement, and two types of sand, i.e. silica sand and limestone sand. The mortars prepared, were then immersed in a 5% MgSO4 solution, at 5, 20 and 50 °C, for 12 months. No damage was observed on the samples exposed to the sulphate solution at 20, and 50 °C. However, serious damage was noted on mortars made with silica sand exposed to the previous solution at 5 °C. Moreover, XRD traces indicated that the formation of thaumasite and ettringite are responsible for the sulfate deterioration of mortars. The samples with limestone sand, at various temperatures; they showed better resistance against sulphate attacks compared to samples with silica sand. The results show that magnesium sulphate attacks at low temperatures are much faster than high temperatures.