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This paper proposes a model of the mechanical behavior of corroded reinforced concrete members subjected to bending under service load. The model is based on the formulation of a macro-element to be used in finite element analysis, having a length equal to the distance between two consecutive flexural cracks and a cross-section equal to the member cross-section. The mechanical formulation is based on the concept of the transfer length necessary for the transmission of tensile load from the reinforcement to tensile concrete through bond. It is thus possible to take into account the effect of reinforcement corrosion on the bond between the steel and concrete by increasing the transfer length as a function of the intensity of corrosion. The variation of the transfer length with degree of corrosion is expressed using a scalar damage parameter. Experimental validation is performed on a 17-year-old beam kept in a chloride environment under its service load.

SP-234 The Canada Centre for Mineral and Energy Technology (CANMET) of Natural Resources, Ottawa, Canada, has played a significant role in Canada for over 40 years in the area of durability of concrete. CANMET, in association with the American Concrete Institute and the Institute for Research in Construction/National Research Council, Ottawa, sponsored the First CANMET/ACI International Conference on Concrete Durability held in Atlanta, Georgia, April 27-May 1, 1987. The refereed proceedings of the Atlanta conference and Montreal conference (the Second CANMET/ACI International Conference on Concrete Durability, held August 4-9, 1991) were published as ACI SP-100 and ACI SP-126, respectively. Unlike the first conference, this second conference was not named after any individual(s), and the future conferences in this series would follow this precedent. In 2006, CANMET, in association with several other organizations in Canada and the U.S., sponsored the Seventh CANMET/ACI International Conference on Durability of Concrete. The conference was held in Montreal, Canada, on May 28-June 3, 2006. More than 75 papers were peer reviewed in accordance with the policies of the American Concrete Institute. The proceedings of the conference, consisting of 50 refereed papers, were published by the American Concrete Institute as ACI SP-234. In addition to the papers that have been published in the refereed proceedings, more than 50 other papers were presented at the conference. A number of these were published as supplementary papers in a special volume. During the conference, special sessions were held on subjects with sulfate attack on concrete and high-performance lightweight concrete. Some of the papers related to these subjects were published in the supplementary volume. Thanks are extended to more than 15 review panel members who met in Budapest, Hungary, in 2002 to review the papers. Without the dedicated efforts of the reviewers, it would not have been possible to have the proceedings ready for distribution at the conference. The cooperation of the authors in accepting reviewers’ suggestions and in revising their manuscripts accordingly is greatly appreciated. The authors are also to be commended for their prompt return of their finalized manuscripts. The assistance of A. Bilodeau, Chair of the audio-visual review panel, is gratefully acknowledged. Thanks are also extended to P. Gupta and C. Mansfield-Joiner for their help in processing the manuscripts. The contributions of the ACI staff for their help in publishing the proceedings on time is also recognized. As an integral part of the conference, a special symposium was held to honor Professor K. Sakata of Japan for his outstanding contributions in the broad area of concrete design and technology over the past 20 years. The proceedings of the symposium were published as a separate volume.

In the current work, an extensive chloride-profiling programme was taken over a seven year period on a series of nine concrete monoliths placed at a marine location. These monoliths were 2.0m high and octagonal in plan with each vertical face 0.66m wide. The monoliths were placed at predefined locations to represent environmental exposure conditions of XS1 (exposed to airborne salt and not in direct contact with sea water) and XS3 (tidal, splash and spray zones) as defined with European Standard EN206-1. The concrete monoliths were constructed in groups of three (one each at the locations defined above): one group, which was used as a benchmark, represented normal portland cement concrete; the second group of monoliths was treated with waterproofing agent (caltite) added at the time off mixing and the third was treated with silane. Chloride profiles were taken at a number of positions on each monolith which were subsequently used to evaluate the performance of the concrete to chloride ingress for different exposure conditions.

Different types of carbonaceous materials have been added to concrete mixes and their effect on the mechanical properties and the corrosion of embedded steel have been studied. Using a constant water/cement ratio of 0.42 the flexural and compression strengths of concrete with different amounts of carbonaceous materials and different curing periods have been determined. Also, the effect of adding some amount of silica fume to the mix formulation has been considered. The addition of small quantities of carbonaceous materials to the mix produces an increase of mechanical strengths and a reduction of the concrete permeability. Due to this smaller permeability the corrosion levels of embedded steel are lower as compared to the ones in an admixture-free mix, in spite of the higher electrical conductivity of the composite.

In the framework of radioactive waste storage, the French atomic energy agency needs to design a concrete container with a service life of 300 years. Regarding durability and mechanical problems, we propose a mixture of proportions of high performance and self compacting concrete including a ternary blend. In order to evaluate the durability of such a formulation a large set of experiments was carried out. Gas and water permeability, diffusivity of chlorides, carbonation, freezing and thawing resistance were studied in laboratory. All results obtained during this study show that the concrete mixture proportions chosen are in accordance with the durability criteria imposed for security reasons. Nevertheless several complementary tests were performed to investigate the microstructure of the material, such as x ray diffraction, thermo-gravimetric analysis or microscope analysis, in order to confirm the results obtained for the durability indicators. In this paper we present all the results obtained during this experimental study, which has been carried out over two years. All values of durability indicators obtained will be introduced in mathematical models in order to verify the service life of 300 years.