This paper discusses the evolution of different methods of disseminating the results of research programs on durability of concrete at the U.S. Army Corps of Engineers Treat Island marine exposure site; beginning with paper reports, and evolving into deployment of modern information technology tools such as a multimedia computer database and a Web based information system. Theses information systems allow side-by side comparison of historical photographs and testing results for different concrete mixtures and support decision-making on the choice of environmentally friendly and durable concrete. With the help of these tools, an easy comparison of the performance of lightweight and normal weight concrete from long-term testing programs at the Treat Island site becomes possible. The results clearly show that structural lightweight and semi-lightweight concrete provides long-term durability in a marine environment. The authors also discuss the advantages of using modern IT tools for research, education and technology transfer for the industry.

Several ageing models are available for the prediction of the mechanical consequences of rebar corrosion. They are used for service life prediction of reinforced concrete structures. Concerning corrosion diagnosis of reinforced concrete, some Non Destructive Testing (NDT) tools have been developed, and have been in use for some years. However, these developments require validation on existing concrete structures. The French project "Benchmark des Poutres de la Rance" contributes to these aspects. It has two main objectives: (i) validating of mechanical models to estimate the influence of rebar corrosion on the load bearing capacity loss of a structure, (ii) qualifying the use of the NDT results to collect information on steel corrosion within reinforced-concrete structures. This project started in 2004 for 2 years. Ten French and European institutions from both academic research laboratories and industrial companies are contributing. This paper presents the project that was divided into several work packages: (i) the reinforced concrete beams are characterized from non-destructive testing tools, (ii) the mechanical behavior of the beams are experimentally tested, (iii) complementary laboratory analysis are performed and (iv) numerical simulations will be finally compared to the experimental results obtained with the mechanical tests.

In this laboratory investigation, the effects of limestone fillerand granulated blast-furnaceslag (GBFS) additions on the mechanical and durable characteristicsof concrete areanalyzed.The evolution of compressive and flexural strength were determined and,waterabsorptionand sorptivity were used to characterize the permeability of concrete. The chloride penetration under continuous soaking was evaluated using the pounding tests and thesulfate resistance of cement was determined using ASTM C1012 test. The results show that, the complementary behavior of limestone filler and GBFS additions permits to obtainconcrete with strength development similar to portland cement with 35 % less clinker, andthe incorporation of GBFS into the mixtures prevents and improves the inadequateperformance of limestone filler cement in chloride and sulfate environments. Consequently,concretes made with ternary cement offer economic and ecological benefits, with similarstrength evolution and similar or better durable properties compared with binary and plainconcretes. However, to assure the reduction of permeability of concrete an adequate curedtime should be proportionate to assure the hydration progress.

The purpose of this research work was to make a drying shrinkage-free concrete (SFC) ,even in non-wet curing conditions. This concrete was produced by the combined use of: a) a water-reducing admixture, based on polycarboxylate (PA), in order to reduce both the mixing water and cement, and increase the amount of aggregate;b) a special polycarboxylate (PA/SRA) including, in its molecular structure, a shrinkage-reducing admixtures (SRA) based on polyethylene glycol capable of reducing the surface tension of liquid water filling the capillary pores; c) an expansive agent based on a special calcium oxide (CaO) manufactured in a kiln at relatively high temperatures (about 1000 °C). Traditional shrinkage-compensating concretes are theoretically based on the restrained expansion produced by portland-cement products containing either calcium sulfo-aluminate or free CaO as expansive agent. However, in practice this effect is cumbersome to achieve because these concretes must be wet-cured, for at least 3-7 days after the final set. On the other hand, with the concrete described in this paper, drying shrinkage is completely compensated even in the absence of wet curing. The concrete is demolded at 3 days and then exposed to air curing. Compressive strength and restrained expansion of laboratory specimens as well field cured concrete are given.

The determination of the starting point of autogenous shrinkage strains is still a point of discussion within the scientific community. Several approaches, each one more or less easy to implement, have been proposed to determine this important point when dealing with low water to binder ratio (W/B) concrete. It is at this moment that external water curing must be applied to control the detrimental effects of the development of early autogenous shrinkage strains because the development of early cracking can be very detrimental for concrete durability. Concrete is continuously subjected to volumetric changes, particularly at an early age, when hydration heat and autogenous shrinkage evolve very fast. It is difficult to separate thermal and plastic shrinkage from shrinkage due to chemical contraction. In large concrete elements, it is appropriate to calculate isothermal shrinkage to reach the starting point of autogenous shrinkage. Neither the temperature criterion alone, nor the penetration resistance test can predict the starting point of autogenous shrinkage, and therefore, the risk of early-age cracking. In this research, the concept of threshold of solidification was coupled with that of temperature rise to more accurately determine the starting point of autogenous shrinkage. An experimental study on the development of isothermal shrinkage of large concrete elements made with different binders was carried out. In order to clarify the effect of the W/B on the importance of the determination of the starting point of autogenous shrinkage, concrete mixtures were made at three W/B: 0.45, 0.35 and 0.26.Isothermal shrinkage was measured using vibrating wire gauges imbedded in a large concrete element. Experimental results show the importance of the correct determination of the starting point of autogenous shrinkage when the W/B is low.