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It is widely recognised that durability of concrete depends on its transport properties, viz. absorption, diffusion and permeability. As concrete cover provides the first line of defence against the ingress of many deleterious substances into the concrete, a measure of its transport properties is vital in assessing its long term performance in the given exposure condition. In new structures the rate of ingress of the deleterious substances could be monitored using array of electrical sensors which are embedded in the cover concrete. For structures which are currently in service, two in situ permeability apparatuses, viz. Autoclam Permeability System (for measuring gas/water permeability and water absorption) and Permit Ion Migration Test (for determining the ionic diffusion) could be employed. These instruments can be mounted on the concrete surface for carrying out the tests. Typical results are presented for these two novel testing systems to illustrate their usefulness for the condition assessment of reinforced concrete structures.
Nanukuttan, S., Basheer, L., Basheer, M., Holmes, N., McCarter, J., Chrisp, M., Starrs, G.: Testing and Monitoring Concrete Using Novel Methods for Predicting Their Long Term Behaviour. Concrete Technology Forum, American Ready Mix Association. 2009.