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As part of a U.S. Navy program for the Modular Hybrid Pier to predict long-term behavior of lightweight concrete in marine environments, the condition of a series of concrete samples taken from a floating boat dock exposed to the Pacific Ocean since 1978 were assessed. Samples originating form the top deck, tidal and submerged zones were tested. Microstructural alterations were investigated by petrographic examinations using optical and scanning electron microscopy. Chloride profiles were measured by chemical analyses. The hulk properties of each series of concrete samples were also determined by porosity measurements, pore solution extraction, chloride migration tests and moisture transmission measurements. The actual state of deterioration of each series of samples was compared to the results yielded by a numerical model. This numer- ical model accounts for the coupled transport of moisture and eight different ionic species (such as chloride and sulfate ions) within unsaturated concrete structures. The software also takes into consideration the chemical equilibrium of ten different solid phases (e.g. ettringite, gypsum and Friedel's salts). Parameters affecting the long-term performance of concrete in seawater are discussed.

It was investigated whether normal ecocement manufactured using as raw materials large amounts of urban wastes such as incinerator ash and sewage sludge, could he used for reinforced concrete. It was confirmed that the fresh properties, strength properties, durability, steel corrosion protecting performance, leaching of heavy metals and workability of the concrete using normal ecocement that contains a reduced amount of chloride ions of around 0.05% were equal to those of concrete using normal portland cement. The results of test executions in several field also confirmed that concrete using ecocement demonstrated Workability equal to that of general concrete. Based on these results, it was concluded that normal ecocement can he used for reinforced concrete.

The work reported in the paper is planned to investigate the air-void system and the frost resistance of self-compacting concrete with slag fine aggregates, produced in refining process of metals, such as blast furnace slag (BFS) fine aggregates, ferronickel slag (FNS) fine aggregates and copper slag (CUS) fine aggregates, which were standardized in JIS A 5011 (Japanese Industrial Standard) as slag aggregates for concrete, The positive use of these slag fine aggregates is being enhanced from the view point of utilization and recycling of industrial by-products. Test results are summarized as follows: (1) The air-void system of self-compacting concrete with slag fine aggregates varied depending on the type of slag fine aggregates used in this investigation. Especially, self-compacting concrete with BFS fine aggregates showed much larger air-voids. This was due to the entrapment of large air bubbles in the course of the mixing process of concretes. (2) The highly durable concrete to frost action can he produced by making the proper air void system with the spacing factor of not more than 300-um.

The built environment of the early 20" century, constructed mainly with rein- forced concrete present serious damage problems. Thus, the establishment for an appropriate damage assessment methodology, that evaluates the concrete durability and service life, is a neccessity. In this study, two buildings of the early 20th century, exposed to an aggressive marine environment are examined: the first is the spa at Kallithea in Rhodes, constructed mainly with reinforced concrete, and the other is the Bell tower of the Church of Saint John Prodromos in Simi, where reinforced concrete was used for repairs. A series of non-destructive Techniques (Fiber Optics Microscopy, ultrasound technique, determination of corrosion potential at the reinforcement and determination of concrete carbonation depth) along with Laboratory Techniques (Grain size distribution, Mercury Intrusion Porosimetry, X-Ray Diffraction, Thermal Analyses) were used. The obtained results revealed that the concrete is carbonated up to the reinforcement bars. The reinforcement has lost the bearing capacity after its 7th lifetime decade. In addition, the nondestructive techniques methodology gave satisfactory results and could be undertaken, for the damage assessment of the modern built environment exposed to aggressive environments (marine or urban).

Contrary to ordinary concrete, where penetration of chlorides is caused by sources outside the concrete, recycled aggregate concrete has an additional source of chlorides, when chloride-contaminated concrete is used as aggregate inside the new concrete. Therefore special specimens were developed to simulate the transport of water and chlorides from recycled aggregate to the surrounding concrete matrix. Conventional methods like weighing and chemical analysis were used to measure the chloride and water transport. It was established, that the pretreatment of recycled aggregate (e.g. moistening) has a large effect on the quantity and the speed of redistribution of chlorides between recycled aggregate and the new matrix. Additional tests with conventional concrete corrosion cells, where individual chloride contaminated recycled aggregates were placed near the embedded steel, showed intense pitting corrosion already after 90 d. The results of rapid chloride migration tests and capillary suction tests are pre- sented for the penetration of chloride and water from outside. For these investigations the composition of the recycled aggregate concrete, especially the type and the proportion of recycled aggregate were varied. The results indicate that the quantity of recycled aggregate has a minor influence on chloride ingress. However, the concrete composition and the type of recycled aggregate can enhance the chloride ingress into recycled aggregate concrete.