Condition Monitoring System for Reinforced Concrete Structures PROBLEM THIS TECHNOLOGY SOLVES: Patent pending concrete condition monitoring system providing ‘real-time’ information on temperature, hydration and water and ionic movement within in the concrete cover-zone which are of relevance in the performance/ durability of concrete exposed to different environmental actions. TECHNOLOGY The performance of the surface zone of concrete (i.e. the cover) is acknowledged as a major factor governing the rate of deterioration of reinforced concrete structures as it provides the only barrier to the ingress of water containing dissolved ionic species such as chlorides. Since concrete is a porous material, with time, chlorides will permeate through the concrete and, ultimately, initiate corrosion of the steel reinforcement and eventual spalling of the concrete (see Figure below). The protective qualities of cover-zone concrete are thus of considerable interest to engineers as the service life of a structure depends, to a large extent, on the permeation properties of the cover-zone. Factors such as pore-size, pore-size distribution, pore continuity, pore connectivity and pore tortuosity, which influence the penetrability of the cover-zone, assume an even greater significance than strength alone. Further, the ability to monitor hydration during the post-curing period, and the continuously evolving pore structure within cover-zone concrete, could be of considerable practical value as it is the properties of the ‘as- placed’ concrete which will play an important role in ensuring adequate protection of the reinforcing steel. This is particularly relevant as ‘slower reacting’ supplementary cementitious materials such as fly-ash and blast- furnace slag are now routinely specified. In-situ monitoring of cover-zone concrete (i.e. surface 50mm or so) is therefore critical in attempting to make realistic predictions as to OVERVIEW The premature deterioration of concrete structures due to corrosion of the steel reinforcement is a world- wide problem, particularly highway structures subjected to de-icing salt used on roads for winter maintenance purposes. In most developed countries, including the UK, around 50% of the construction budget is devoted to repair and maintenance of structures with over 30% of this expenditure on concrete structures. In addition, our infrastructure has now reached an age where capital costs have decreased, but inspection and maintenance costs have grown, constituting a major part of the recurrent costs of the infrastructure. Traffic delay costs due to inspection and maintenance programmes are already estimated to be between 15%-40% of the construction costs. The ability to monitor water and ionic ingress through the concrete cover-zone would provide an early warning of incipient problems enabling the planning and scheduling of maintenance programmes, hence minimising traffic delays resulting from road/lane closures. The development of integrated monitoring systems for new reinforced concrete structures could also reduce costs by allowing a more rational approach to the assessment of repair options; and, co-ordination and scheduling of inspection and maintenance programmes. This system provides such data over the lifetime of the structure allowing informed (and timely) preventative maintenance decisions to be with greater confidence. The system can be interrogated remotely. Distinctly Ambitious www.hw.ac.uk