In this paper the results of an investigation into the frost salt scaling resistance of cement mortars bearing extra-fine slag (EFS) with Blaine fineness of 500 kg/m2 is reported. The water to cement ratio of the mortar specimens is kept as 0.45. EFS was used as a replacing material for both European CEM III /B blast furnace slag cement and CEM I normal portland cement. Within the framework of this study, the carbonation resistance and pore structure of the cement mortars are also studied. Carbonation resistance is measured by phenolphthalein method after accelerated carbonation test in 3% CO2 chamber. Pore structures of the samples are evaluated by means of mercury intrusion porosimetry. The microstructures of the samples are further characterized by environmental electron microscope. It appears that EFS replacement in CEM III /B and CEM I decreases the frost salt scaling durability of mortars.

The presently standardized ways in Europe to achieve a sufficient durability of concrete for outdoor elements are not always successful. The resistance tests on concretes against single attacks (e.g. frost, frost-de-icing salt, sulfate, alkali-silica reaction) – as they are presently practiced – do not seem to be effective to assess the durability. Also the exami-nation of single specific concrete properties, e.g. permeability parameters, is not an appropriate method. Outdoor elements are exposed to complex environmental influences, i.e. not only to a frost or frost/de-icing salt attack. Likewise, the problem of the alkali-silica reaction (ASR) with alkali-reactive slow/late aggregates is not sufficiently treated. Based on the present state of knowledge the latest approaches in developing performance testing method shall be described. A new type of climate chamber is used to evaluate the durability of concrete for outdoor elements under simulated climate conditions. The principal capability of cyclical storage with alternating temperature and moisture condi-tions in order to achieve an acceleration effect in the simulation of weather conditions on concrete has been proved in previous comparative investigations in our institute. Results of different investigations by means of this new type of climate chamber regarding high performance concrete, normal concrete with different types of cement and ASR-vulnerable concretes will be presented.

Instead of the conventional method for evaluating an apparent diffusion coefficient of chloride ions (Cl-) from experimental Cl- concentration profile, this study introduces a novel method to estimate an effective diffusion coefficient (De) and non-linear binding parameters (a, b) of Cl- from a Cl- concentration profiles measured by electron probe micro analysis (EPMA). This estimation is made by the combination of numerical analysis by the finite-difference method of the non-linear diffusion equation and optimizing calculations. By using this method, De, a and b are estimated for several kinds of concrete having various type of cement and several levels of water-cement ratio. The estimated values of De show a positive linear relationship with values of De obtained by migration tests. The estimated values of a show a good correlation with the alumina content in cement as expected. These results indicate the validity of this method for estimating parameters required for predicting future Cl- concentration profiles.

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.

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.