The influence of silica fume on the factors affecting the corrosion of reinforcement in concrete: a review
Rajaiah Selvaraj, Central Electrochemical Research Institute, Tamilnadu, India Srinivasan Muralidharan, Central Electrochemical Research Institute, Tamilnadu, India Seshadri Srinivasan, Central Electrochemical Research Institute, Tamilnadu, India
The effect of silica fume in concrete is reviewed from the point of view of chloride diffusion, carbonation, oxygen diffusion, the pH of the pore solution and electrical resistivity, as they are the main parameters influencing the corrosion phenomenon in concrete.
Structural safety is a part of general safety in a society. Safety factors should conform to a general rationale for all life safety. Two rationales are presented here, using a principle of time economy and using social indicators. The common-sense time principle of risk management states that a `life-saving' alternative, if it is truly to save lives, should return to the community more years of life in good health than the years of work consumed to pay for its cost. Alternatively, a risk acceptability criterion can be derived from a compound social indicator that reflects general benefit to society and that is a function of gross domestic product and life expectancy. To be acceptable, alternatives should increase the social indicator. The two compound social indicators, the Life Quality Index and the Human Development Index, yield practically identical criteria for risk acceptance.
Carbon-based tendons in the Dintelhaven Bridge, the Netherlands
A. H. J. M. Vervuurt, TNO Building and Construction Research, the Netherlands N. Kaptijn, Dutch Ministry of Transport and Public Works W. B. Grundlehner, Spanstaal BV, the Netherlands
In mid-2001 the final two bridges over the River Dintelhaven in the harbour area of Rotterdam were put into use. Both bridges are concrete box girder bridges and have been erected using the balanced cantilever method. In the first bridge, with a main span of about 185 m, four (external) tendons each with 91 carbon fibre reinforced wires (5 mm diameter) have been applied next to conventional steel tendons. The project is the result of an initiative that was started in 1994 by the Civil Engineering Division of the Dutch Ministry of Transport and Public Works and the CUR (Dutch Centre for Civil Engineering Research and Codes). In order to guide the activities, with regard to the application of the carbon fibre reinforced plastic (CFRP) tendons in the Dintelhaven Bridge, experiments were carried out at TNO Building and Construction Research, focussing upon the long- and short-term behaviour of the CFRP wires and tendons. In this paper the results of these tests are presented. Moreover, in the paper, attention is paid to the manufacturing of the tendons, as well as the installation of the tendons in the bridge.
