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Today most major reinforced concrete (RC) projects require a durability report which inevitable includes a calculation on the likelihood of carbonation of the concrete and/ or the extent of the ingress of chlorides. More often than not if this means that carbon steel will corrode within the service life of the structure then the proposed solution will be SSR. Predictive modelling has redefined selective use of SSR to mean the depth within the concrete where carbon steel needs to be replaced by SSR.
Predictive modelling is not the easiest of subjects to understand and there are a lot of variables within the assumptions of deterministic predictive models. Designers around the world today use predominately Life 365 or AGEDDCA from Concrete Society technical Report TR61 but there are others. Predictive modelling is used for structures in known high risk environments or those with service lives greater than 50 years. Interestingly both models produce results which challenge the application of standard codes of practice for durability, e.g. E.C.2.
Despite the draw backs of the performance approach of predictive modelling it is certainly a step forward from the current prescriptive approach which would also share some of the draw backs. Whilst a performance approach may be some way off yet for everyday use it does drive the need for us at Outokumpu to produce accurate information on the corrosion resistance of our SSR and is worthy of wider study outside of the world’s largest projects. To this end we have commissioned a world expert in concrete durability reports, Bryan K Marsh of Arup Materials Consulting to write a definitive critique and informative report on predictive modelling. This can be down loaded from below.
Stainless Steel Reinforcement - The use of predictive models in specifying selective use of stainless steel reinforcement
There is also a disc with an excel spreadsheet model to illustrate the main points from the report on predictive modelling. We call this the “Simple Representative Model” and it is available from your local ABC manager (go to contacts tab on top tool bar) or to down load the model from here. Please note that the model should be used in conjunction with reading the report. It is intended to illustrate the parameters used in predictive modelling rather than providing definitive answers for projects. The file is tested for compatibility with Microsoft Excel 2003 running on Windows XP 32 bit. Compatibility problems may be experienced if using a different operating system/version
Simple Representative Model
Instructions: In order to use the “Simple Representative Model(SRM)” in the most optimal way. Firstly save the file to your computer and macros must be enabled within Microsoft Excel.
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