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In 1989, a field inspection of concrete structures in selected geological areas showed that nearly all known structures with alkali-aggregate reaction (AAR) were situated within or close to areas with known potentially reactive bedrock of metarhyolite, metasandstone, metagreywacke, and phyllite. Such areas may, therefore, be interpreted as areas with a high risk of AAR, when local aggregate deposits and Norwegian high-alkali cements are used. To get an overview of the extent of AAR in the whole of Southern Norway, a survey inspection of randomly distributed road bridges and dams older than 10 years was carried out during the summer of 1990. The decision was made to use map cracking as an indicator for AAR and to measure maximum crack width and estimate area percent of map cracking. The data from the inspections of 468 structures have been put into a database (as well as other available information, e.g., laboratory analyses results). A distribution map plot of inspected structures has been constructed and used to locate structures into two types of geological areas, namely, structures located in potentially reactive bedrock areas, and structures located in supposed innocuous bedrock areas. Data processing shows that map cracking is common in structures in Southern Norway and is more frequent in potentially reactive bedrock areas. In potentially reactive bedrock areas, average maximum crack widths and area percent of map cracking is larger than in supposed innocuous bedrock areas. A surprising peak height of increased maximum crack width has been revealed to occur in structural elements built around 1950 to 1960. This peak height is most significant in structures situated in supposed innocuous bedrock areas. The cause of this increased cracking in structures built around the 1960s is unknown but could be caused by a very high alkali content in Norwegian cement at that time.

High-strength lightweight concrete is a promising material with many advantages over normal weight concrete in the construction of offshore structures that are submerged underwater for most of the time. In these structures, which are subjected to dynamic loading, the flexural fatigue strength and endurance limit of concrete submerged in water are important design parameters because these structures are frequently designed on the basis of fatigue loading. Presents the results of an experimental investigation to determine the flexural fatigue strength of lightweight concretes made using expanded shale aggregates. Six different concretes were investigated in this study. A total of 120 prisms (20 prisms of 76 x 102 x 406 mm, in size for each concrete) were tested in flexural fatigue loading of 20 cycles per sec (Hz) when they were submerged in water. The prisms that survived 2 million cycles of fatigue loading were tested in static flexure to demonstrate their residual strength (modulus of rupture). The test results are compared with the results of similar concretes tested in air in an earlier investigation. The static flexural strength (modulus of rupture) and the flexural fatigue strength were higher for the specimens tested underwater compared to similar specimens tested in air. In general, there was no reduction in the endurance limit (the ratio of the fatigue strength to the modulus of rupture) for the lightweight concretes when they were submerged in water. There was an increase in the residual static flexural strength for the prisms previously subjected to 2 million cycles of fatigue stress underwater.

Cracking of concrete, whatever its origin (mechanical, physicochemical, thermal, ...) is a factor accelerating the deterioration of the material. The knowledge of the transfer properties of sound concrete and of cracked concrete is essential for predicting its durability since the deteriorating mechanisms (freezing, corrosion, lixiviation) are related by the flow of aggressive (liquid or gas) agents through the porous body. An experimental system has been developed with the purpose of estimating the increase in permeability resulting from mechanically induced cracking. A specimen of concrete is subjected to uniaxial or biaxial tension, and the water permeability is measured in the direction perpendicular to the axis of loading. The tests are designed and monitored to collect data useful for modeling of concrete structures: the material is in tension (and not in compression, as it is more classical in studies of damage-permeability coupling), and the permeability is measured with open cracks. The response in tension being unstable, the geometry of the specimen has been designed with great care, using knowledge previously accumulated in ``PIED" uniaxial diffused damage tension test. It results that the transfer properties are evaluated in the most unfavorable context. The way the specimen has been designed for these measurements is detailed, then the experimental frame (triaxial press ASTREE) is presented, and some experimental results on preliminary tests are given.

For the calculation of civil engineering structures, designers employ the mechanical aspect underestimating the physicochemical phenomena in connection with the hydration of cement paste. Although the mechanical approach is widely sufficient for classical structures, this is not the case for large structures like dams, where thermophysical phenomena play a leading part. After a short analysis of the degradation observed on a roller compacted concrete dam, showing the importance of the control of hydration effects on mass concrete, the authors present a thermomechanical model able to describe the main evolutions of concrete properties with aging. Application to the Riou dam shows the ability of the approach to simulate temperature, strains, and stresses and, as a consequence, the risk of damage for the structure. Cracks in the middle of the dam are properly represented. This approach permits determination of the position and number of construction joints and setting the schedule of construction as thickness of concrete layers or maximum delay between two layers.

Reinforcement corrosion due to chloride ingress is the most common cause of concrete deterioration in Norway. A wharf with dimensions of 270 x 25 m was built in 1965 to 1966 and required partial repairs in 1980, 1986, and 1989 to 1990. The repair work included some research and development. The conclusion of the 1989 inspection was that no corrosion activity was evident in the earlier repaired areas. Repair mortar with silica fume had somewhat lower chloride ingress and significantly higher electrical resistivity than mortar without silica fume. Latex addition to the repair mortar showed the same effect, as well as a reduced water content. The main conclusion is that materials and working procedures used for the 1980 repair have resulted in a satisfactory service life of at least 10 years.