The Faroe Bridges are two bridges connecting the Danish islands of Zealand and Falster crossing the island of Faroe. The bridges carry the southern motorway which connects Copenhagen with Germany and the rest of Europe. The total length of the bridges is 3.3 km. The bridges were constructed in the period from 1980 to 1997 several investigations were carried out on the columns. The objective was to evaluate the risk of initiation of reinforcement corrosion as a result of chloride penetration. The investigations included, inter alia, measurements of chloride content (in dust samples and on dust ground from drilled cores), measurements of reinforcement corrosion, concrete condition, etc. The future chloride penetration has been modeled using a probabilistic approach. It can be concluded that the decrease in chloride penetration ratio that might have taken place in the time span from 1988 to 1997 was insignificant in comparison with the random variation caused by the concrete characteristics. It has been calculated that corrosion initiates after 15-40 years in the tidal zone (level .5 m above water) and after 25-40 years in the splash zone (level 1.5m above water) given a critical chloride content of .5-.10% CI by mass of concrete and the specified cover of 50mm. As a pilot project cathodic protection was installed on one column using magnetite anodes in the sea. It was found that the conditions believed necessary to prevent corrosion were established below water level and in the tidal zone.

The results tests on rock aggregate and manufactured sand from Paleozoic carbonate rocks from quarries in SW Ontario were compared those of mortars containing the manufactured sand. The aggregate tests included petrographic analysis, water absorption and adsorption, linear expansion under various conditions, analysis, water absorption and adsorption, linear expansion under various conditions, thermal expansion, insoluble residue content, micro-Deval abrasion loss, freeze-thaw loss, and rate of settlement of -.075 mm. (-#200) fraction. The mortar tests consisted of drying shrinkage, water absorption and adsorption, linear expansion under various conditions, thermal expansion, and scaling and freeze-thaw loss. Multivariate statistical techniques (factor, D-cluster, tree, and stepwise regression analysis) were used to compare and group the properties of aggregates and mortars. Factor analysis showed that the results could be grouped into four factors: (1) Durability factor, (2) Porosity factor, (3) Thermal and (4) Isothermal Expansion Factors. The first two factors were found to be the most encompassing, and grouped the most significant test for aggregate and mortar frost resistance. Stepwise regression predictive models of mortar resistance to salt scaling were developed, based on results of simpler tests on aggregates. K-cluster analysis successfully classifies the aggregates and mortars made from them into good and poor categories. The tree analysis provides the passing limits that can be applied to aggregate tests of any defined group of aggregates.

Within the framwork of the "BHP 2000" French National Project, a long-term experimental study is carried out in order to assess the durability of fifteen concretes with 28-day compressive strength ranging from 20 to 130 MPa. The properties of these concretes are first studied on sampled in laboratory conditions. Also, reinforced-concrete test specimens are monitored over the years at four different field exposure stations. The experimental results of compressive strength, gas permeability, and carbonation death obtained in the laboratory on the water-cured 28-day old samples are compared here with some of the available field data. The ranking of the different concretes with respect to their durability is deduced in both cases. Other laboratory measurements, such a chloride diffusivity, capillary coefficient, and deicing-salt scaling resistance, are also presented and discussed in this paper. For each type of concretes, the influence of mixture-parameters, such as the water-to-cement ratio, the presence of entrained air or of pozzolanic admixtures, on the different properties is analyzed. The influence of the environmental conditions on the field data is also discussed. The various trends observed on the durability-related properties are interpreted o the basis of the microstuctural characteristics of the materials. The paper focuses on the behavior of high-performance concretes. A superior ability to limit gas or liquid transfers within the material is observed for these concretes. But, it is found that the presence of entrained air increases their gas permeability, indicating an increased potential risk of corrosion of the reinforcement, without systemically enhancing the deicing-salt scaling resistance of the concrete. Most of the non-air entrained HPCs do not exhibit good performance when submitted to accelerated freezing and thawing cycles in the presence of slats. All of these results have to be confirmed by the long-term monitoring of the structural elements.

In many situations concrete structures may be exposed to temperatures higher than those assumed as normal environmental conditions. This can be produced by accidental causes, such as fires. In other cases, high temperatures can be generated by the characteristics of the structural application, as in walls, pipes or vessels in some specific industries (nuclear, chemical processing, metallurgy). Most of the knowledge about concrete behavior is based on experimental results obtained on specimens at normal temperatures, which are not representative of the material properties under extreme conditions. In this paper, an extensive analysis of the physical and mechanical properties of normal and high-strength concretes exposed to temperatures up to 700 degrees C is presented. Ultrasonic pulse velocity, static and dynamic modulus of elasticity, and strength and deformations (axial and transversal) under compressive loading were measured. In addition, flexural and splitting tensile strength and the fracture energy were measured. Also, other tests for determining the water permeability, water penetration and absorption were performed on concrete slices with the aim of analyzing the differences in the physical properties of the cover and bulk concrete.

This study evaluates effect of metakaolinite on the chemical resistance of standard cement mortars produced from portland cements of different C3A content, ranging from 3.3% to 11.4%. The metakaolinite was produced by burning of kaolin clay at different time and temperatures, specially selected to ensure the highest pozzolanic activity, as measured by ASTM method. The chemical resistance was evaluated through the measurements of strength, shrinkage and expansion tests on the samples stored in water and chemical solutions. The porosity and microstructure was also investigated. As it appeared, the metakaolinite admixture did not change substantially the standard properties of mortars, though their chemical resistance was markedly improved.