El Boquerón reservoir (Canary Islands, northern hemisphere) is waterproofed with an ethylene-propylene-diene terpolymer (EPDM) geomembrane (GM). To evaluate the durability of EPDM GMs in hydraulic applications, the characteristics of the EPDM GM (resin and additives) installed in the El Boquerón reservoir were followed for over 21 years. The results of this study are presented herein and show that, based on measurements of specimens from the north and south slopes of the reservoir, the orientation of the GM influences its ageing, with the north slope in the coronation or crest area ageing the most rapidly. Over the years, the El Boquerón EPDM GM oxidised, which may be the main cause of crosslinking in the EPDM. In turn, crosslinking could be the mechanism behind some of changes observed in the EPDM GM characteristics over time. In addition, some of the mechanical characteristics of the EPDM GM were influenced by the additives in the formulation; in particular, the loss and oxidation of paraffinic oils. However, despite the age-induced evolution of the mechanical and physicochemical characteristics of the GM, the El Boquerón EPDM GM, after 21 years of exposure, still satisfies the minimum requirements established by French standards for virgin GMs.

Reinforcement corrosion leads into several damages which influence the structural load-bearing capacity, among which can be mentioned the cracking of concrete cover. This work study formulations to estimate the crack width of structural elements from the data of corrosion rate measured in two structural elements, made in 1990, with chlorides added in the concrete mix and laboratory test from other authors. The structural elements, one T beam and one column, were exposed at the atmosphere of Madrid, Spain. Two expressions have been fitted to the results: w = k P x / (c/φ) and w = k P x / R o , where w is a crack width in the time, k is a proportional factor, P x is the corrosion penetration in the time, c/φ is the concrete cover/diameter relation and R o is the original radius of the bar. The first expression has resulted the most adequate.

The cast in-situ concrete offers a good compressive strength, but their tensile strength is very low. If it is reinforced placing steel bars, the material resulting (reinforced concrete) can resist the constructions efforts. Therefore, reinforced concrete is based on combining the work in compression of the concrete with the steel tensile strength.

This paper shows how the corrosion and mechanical actions can be taken into account in a simple model for the assessment of structural elements. This work is framed in the Project "Benchmark des Poutres de La Rance" in which several partners have participated. The Project tried to characterize the degradation of reinforced and prestressed concrete structures after an aging in marine atmosphere with nondestructive methods and to evaluate different existing models for the structural assessment. For this aim a 4-point bending test was performed on six prestressed concrete beams. The model gives a reasonable approach for the assessment of structural elements. Similar rules can be adopted for other failure modes. It is important to notice the need of reliable input data for the assessment and also the need of integration of deterioration processes in design.