Limiting concentrations for ultra high strength concrete in contact with aggressive solutions
Based on the scientific literature and the results of the priority program “Sustainable Building with Ultra-High Performance Concrete” of the Deutsche Forschungsgemeinschaft (German Science Foundation) the German Committee for Structural Concrete is developing a guideline for Ultra High Strength Concrete (UHSC). One aspect is the durability in contact with aggressive solutions. The development of the guideline is an ongoing process. But some results can be presented, that will probably be accepted by the committee. Although it is widely accepted that UHSC has an increased durability, quantitative data usable within a concept of equivalent performance according to EN 206 are very rare, beginning with the simple question of acceptable damage depths. The contribution presents time dependent damage depths of several UHPC mixtures in contact with different acids and ammonium nitrate solution and other information about chemical attack. In addition the influences of non-static boundary conditions, curing and steel fibres are discussed. Allowed damage depths, measured with a normal strength reference mortar are shown. The results lead to the suggestion that UHSC in contact with aggressive solutions can be used up to the following limiting concentrations without additional protection. Ammonium solutions: 1000 mg/l NH4+, strong dissociated acids: pH 3.5, solutions with aggressive carbon dioxide: until saturation. A prerequisite of this limiting concentrations is that the high strength of the concrete is based on a very low water-cement-ratio and a particle packing optimization. To our opinion the limiting values for sulphate and magnesium solutions can not expanded at the moment, because the data base is too small. Additional research is needed in these cases.
aggressive carbon dioxide
690: Hausbau, Bauhandwerk
LIMITING CONCENTRATIONS FOR UHSC_Frank Schmidt-Döhl.pdf