Pore selection composition and other factors influencing the corrosion risk of reinforcement in concrete.

Investigations of (i) chloride binding in cement (ii) electrical conductivity of drying concrete and (iii) microstructure of cement paste were carried out. It is shown that the residual chloride concentration of the pore solution varies considerably, inter alia, on the w/c-ratio and type of chloride salt added. The C1/OH-ratio, on the other hand, increased with decreasing w/c-ratio, so that neither the total chloride content nor the C1-OH-ratio of the pore water can be a reliable indicator for the assessment of corrosion risk. The measurements of electrical conductivity of drying concrete indicate that a complete stagnation of corrosion in outdoor drying concrete seems most unlikely but the rate of corrosion can be reduced considerably. The investigations of microstructure of cement paste during hardening by small angle X-ray scattering showed that both the inner surface and the space filled by mass is 'fractal". For the characterization of the porous, rough structure of hardened cement fractal geometry is better suited than the classical (Euclidian) description of the internal surface area of the material. (A)