The premature deterioration of concrete structures is a world-wide problem. 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 . Demands for enhanced performance create a pressing need to be able to determine, with an acceptable degree of confidence, the anticipated service life of concrete structures. Monitoring deterioration 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. It is now recognised that integrated monitoring systems and procedures have an important role to play.in the total management of structures, which involves both whole-life economics and life-cycle calculations, When data from monitoring systems are used with improved service-life prediction models additional savings in life cycle costs could result. Recent reports from both CIRIA (2008) and EPSRC (2009) highlight the need for the development of sensor technology for 'intelligent' montoring of structural health.Since it is the concrete cover-zone (covercrete) which protects the steel from the external environment, the ability to continuously monitor the covercrete would allow a more informed assessment of the current and future performance of reinforced concrete structures. In-situ monitoring of cover-zone concrete - in real time - could thus assist in making realistic predictions as to the in-service performance of the structure; likely deterioration rates for a particular exposure condition, compliance with the specified design life and as an early warning indicator of incipient problems. Set against this background, this proposal exploits previously funded studies to deliver an intelligent, durability monitoring system thereby addressing a pressing need in the total management of concrete structures. The development of sensors and associated monitoring systems to assess covercrete performance would thus form an important component in the inspection, assessment, maintenance and management of structures.This follow on funding proposal addresses this subject. A patent application has recently been filed detailing a multi-electrode electrical conductivity and temperature array and rebar attachment facility (Patent No. 0918449.0). The array gives a detailed picture of the spatial distribution cover-zone properties and their variation with time i.e. it allows an integrated assessment of the cover-zone response to the external environment. The thrust of the proposal will be further technical development of the testing methodology and monitoring technology so as to provide a 'market-ready' product for intelligent monitoring of concrete structures.

Building stone has a finite life that can be drastically curtailed when it is placed in the often-aggressive environments experienced in today's urban settings - yet stone masonry is still widely recognized as an adaptable and sustainable construction material, with a low carbon signature, and as a repository of much of the world's tangible cultural heritage. Arising from this, it is essential that the choice of new and replacement stone and the conservation of decaying stone is underpinned by a detailed knowledge of how different stone types decay in specific environments and what factors trigger decay and control its rate once it is initiated. Data are limited from the wide range of stone types seen in structures existing today - the performance characteristics of only a limited number of comparatively durable stones are known and these are largely resistant to physical damage and decay is driven primarily by dissolution. The rate of solution of stones is influenced by factors such as rainfall amount, timing, atmospheric conditions and chemistry and thus, with knowledge of micro-environmental conditions in and around the building stone, decay rates are largely predictable from short-term observation. Despite rather advanced non-destructive methods currently used for assessing the deterioration process and their rates, the fate and extent of inner contamination of building materials remains largely unaccounted for by such methods. Therefore qualitative online health monitoring of these building materials using embedded sensors is essential, not only from the standpoint of economic planning and maintenance, but also on cultural, technical and scientific grounds. Novel sensor systems designed specifically for use in buildings constructed from stone can provide the data that conservators need which enable them to understand better the complex processes that are on-going and to model better and thus plan repair and maintenance procedures in a cost efficient and timely way. This work builds upon several previous EPSRC grants into both fibre optic sensor systems, civil structural monitoring and heritage stonework. However in particular this follow on application builds upon the successful technical achievements of a grant focusing on the test, evaluation and design of a suite of new sensor systems for stonework monitoring for both moisture and chloride transport. The work enabled a more detailed evaluation of the decay processes and the beginning of a better understanding of several key applications-focused issues from that grant funded. Recognizing that the Follow-on Fund is concerned with development towards an identified commercial opportunity, this project can be summarized as the development, commercialization and marketing of fibre optic sensor systems for monitoring ingress of moisture and moisture-borne salts in the context of structural monitoring and decay prevention of stonework, both historic and modern. Through carefully considered technical and commercial plans, it is intended to refine the sensors for the specific monitoring environments of stone masonry strucures and develop probes which can be used in stonework in a minimal invasive manner. The commercial feasibility will be established through in situ evaluation, market testing and working closely with an SME with specialised knowledge in monitoring the built environment.

Stone is widely recognised as a sustainable construction material and as a store of much of the world's tangible cultural heritage. With this recognition has come an understanding that stone has a finite life that can be drastically curtailed when it is placed in the often-aggressive urban environments. In particular, many common building limestones experience seemingly unpredictable, episodic and sometimes catastrophic breakdown as stone strength is exceeded by gradual decay, the slow accumulation of internal stresses and/or subjection to extreme external stresses such as a severe frost. Episodes of rapid decay may be interspersed with periods of relative stability marked by, for example, the formation of pollution-derived calcium sulphate crusts. To control potential catastrophic decay it is therefore necessary to understand why rapid retreat is triggered, what allows it to continue, how it can be halted and how the causes can be avoided in the first place. This is particularly true where inappropriate conservation could accelerate decay, and where choices have to be made between possible replacement stone and stone selection in relation to new structures. To achieve this understanding four questions need to be asked.1. What processes are responsible for rapid retreat?2. What physical, chemical and mineralogical characteristics determine stone susceptibility to rapid retreat and how do these properties change during decay?3. How do microclimatic conditions at and beneath the stone surface change as stone retreats and how do these influence decay mechanisms?4. What permits continued weathering despite rapid loss, of weathered material in which, for example, damaging salts are concentrated?This interdisciplinary project will examine these questions through field studies of stone structures in Oxford and nearby areas built of oolitic limestone (e.g. Bath and Cotswold limestones) that is prone to rapid retreat. Linked to this will be the development of fibre optic sensors that will allow moisture and salt movement within individual blocks to be monitored in relation to environmental conditions, including temperature, relative humidity and surface wetting. These data, and the same sensor technology will be combined with analyses of weathered stone to design laboratory experiments using different varieties of Bath Stone to simulate breakdown patterns and the dynamics of salt and moisture movement as blocks retreat and are progressively sheltered. Results from field studies and controlled laboratory experiments will be combined to explain (model) the factors that determine overall susceptibility to either rapid retreat or stability and the operation of the processes responsible for decay. In particular, results will be used to determine what triggers positive and negative feedbacks that respectively accelerate and decelerate change within the stone decay system. This understanding will be used, in discussion with end-users, to develop protocols for limestone conservation and the selection of new and replacement stone matched to specific environmental conditions.

Stone is widely recognised as a sustainable construction material and as a store of much of the world's tangible cultural heritage. With this recognition has come an understanding that stone has a finite life that can be drastically curtailed when it is placed in the often-aggressive urban environments. In particular, many common building limestones experience seemingly unpredictable, episodic and sometimes catastrophic breakdown as stone strength is exceeded by gradual decay, the slow accumulation of internal stresses and/or subjection to extreme external stresses such as a severe frost. Episodes of rapid decay may be interspersed with periods of relative stability marked by, for example, the formation of pollution-derived calcium sulphate crusts. To control potential catastrophic decay it is therefore necessary to understand why rapid retreat is triggered, what allows it to continue, how it can be halted and how the causes can be avoided in the first place. This is particularly true where inappropriate conservation could accelerate decay, and where choices have to be made between possible replacement stone and stone selection in relation to new structures. To achieve this understanding four questions need to be asked.1. What processes are responsible for rapid retreat?2. What physical, chemical and mineralogical characteristics determine stone susceptibility to rapid retreat and how do these properties change during decay?3. How do microclimatic conditions at and beneath the stone surface change as stone retreats and how do these influence decay mechanisms?4. What permits continued weathering despite rapid loss, of weathered material in which, for example, damaging salts are concentrated?This interdisciplinary project will examine these questions through field studies of stone structures in Oxford and nearby areas built of oolitic limestone (e.g. Bath and Cotswold limestones) that is prone to rapid retreat. Linked to this will be the development of fibre optic sensors that will allow moisture and salt movement within individual blocks to be monitored in relation to environmental conditions, including temperature, relative humidity and surface wetting. These data, and the same sensor technology will be combined with analyses of weathered stone to design laboratory experiments using different varieties of Bath Stone to simulate breakdown patterns and the dynamics of salt and moisture movement as blocks retreat and are progressively sheltered. Results from field studies and controlled laboratory experiments will be combined to explain (model) the factors that determine overall susceptibility to either rapid retreat or stability and the operation of the processes responsible for decay. In particular, results will be used to determine what triggers positive and negative feedbacks that respectively accelerate and decelerate change within the stone decay system. This understanding will be used, in discussion with end-users, to develop protocols for limestone conservation and the selection of new and replacement stone matched to specific environmental conditions.

Building stone has a finite life that can be drastically curtailed when it is placed in the often-aggressive environments experienced in today's urban settings - yet stone masonry is still widely recognized as an adaptable and sustainable construction material, with a low carbon signature, and as a repository of much of the world's tangible cultural heritage. Arising from this, it is essential that the choice of new and replacement stone and the conservation of decaying stone is underpinned by a detailed knowledge of how different stone types decay in specific environments and what factors trigger decay and control its rate once it is initiated. Data are limited from the wide range of stone types seen in structures existing today - the performance characteristics of only a limited number of comparatively durable stones are known and these are largely resistant to physical damage and decay is driven primarily by dissolution. The rate of solution of stones is influenced by factors such as rainfall amount, timing, atmospheric conditions and chemistry and thus, with knowledge of micro-environmental conditions in and around the building stone, decay rates are largely predictable from short-term observation. Despite rather advanced non-destructive methods currently used for assessing the deterioration process and their rates, the fate and extent of inner contamination of building materials remains largely unaccounted for by such methods. Therefore qualitative online health monitoring of these building materials using embedded sensors is essential, not only from the standpoint of economic planning and maintenance, but also on cultural, technical and scientific grounds. Novel sensor systems designed specifically for use in buildings constructed from stone can provide the data that conservators need which enable them to understand better the complex processes that are on-going and to model better and thus plan repair and maintenance procedures in a cost efficient and timely way. This work builds upon several previous EPSRC grants into both fibre optic sensor systems, civil structural monitoring and heritage stonework. However in particular this follow on application builds upon the successful technical achievements of a grant focusing on the test, evaluation and design of a suite of new sensor systems for stonework monitoring for both moisture and chloride transport. The work enabled a more detailed evaluation of the decay processes and the beginning of a better understanding of several key applications-focused issues from that grant funded. Recognizing that the Follow-on Fund is concerned with development towards an identified commercial opportunity, this project can be summarized as the development, commercialization and marketing of fibre optic sensor systems for monitoring ingress of moisture and moisture-borne salts in the context of structural monitoring and decay prevention of stonework, both historic and modern. Through carefully considered technical and commercial plans, it is intended to refine the sensors for the specific monitoring environments of stone masonry strucures and develop probes which can be used in stonework in a minimal invasive manner. The commercial feasibility will be established through in situ evaluation, market testing and working closely with an SME with specialised knowledge in monitoring the built environment.