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CURATOR
A pinboard by
Shima Taheri

Research Associate in Photonics, Macquarie University

PINBOARD SUMMARY

This project aims to develop a sensor system for health monitoring of concrete structures.

Corrosion and corrosion mitigation are the most significant costs faced by Australian water utilities, accounting for about hundreds of millions dollars per annum. Corrosion is the primary factor affecting the longevity and reliability of pipelines. Acid attack has been identified as the prominent concrete ailment in sewer and usually is confined to the cement paste. This results in calcium depletion of concrete surface and leads to corrosion and softening of concrete surface. This is most analogous to the Osteoporosis in human where we have calcium depletion from bones. The water flow and flood can wash away softened concrete ultimately this results in thinner pipes and to an increased risk of structural collapse and failure in long term. Sewer pipes are like human veins and they are crucial part of a healthy city. Since they are underground, health monitoring of these structures is very hard. This silent corrosion pose a significant risk to our city Sewer pipes like Sydney with thousands of kilometers network of pipes. In order to enhance the service life of the expensive and important sewer systems as well as to counter the silent corrosion caused by acid attack, water utilities are following three approaches: (a) continues sewerage treatment to reduce the H2S level; (b) surface treatment of the concrete; and (c) installing corrosion resistant sewer pipes. However, it is still unknown to what extent these mitigation strategies factually contribute to the reduction in corrosion in concrete sewer pipes.Hereby we developed a methodology that could be used to quantitatively measure concrete quality parameters like temperature, humidity, pH, H2S level and strain which are crucial factors in detecting deterioration in concrete sewer pipes. This system is working by adding fiber optic sensors to concrete structures and gives a monitoring dashboard to water utilities to detect any abnormality in underground pipes and enable water utilities to act on time. We have also developed a methodology for periodical structural and mechanical core evaluation by the combination of Neutron Tomography (NT), Scanning Electron Microscopy (SEM) and Microindentation Mapping techniques. Combination of every day sensor readings and periodical core evaluation can be then used as part of asset management strategies in order to address maintenance challenges such as surface treatment of corrosion impacted pipes or sewage chemical dosing in the most efficient manner.

8 ITEMS PINNED

Materials, Vol. 10, Pages 5: Quantification of the Service Life Extension and Environmental Benefit of Chloride Exposed Self-Healing Concrete

Abstract: Formation of cracks impairs the durability of concrete elements. Corrosion inducing substances, such as chlorides, can enter the matrix through these cracks and cause steel reinforcement corrosion and concrete degradation. Self-repair of concrete cracks is an innovative technique which has been studied extensively during the past decade and which may help to increase the sustainability of concrete. However, the experiments conducted until now did not allow for an assessment of the service life extension possible with self-healing concrete in comparison with traditional (cracked) concrete. In this research, a service life prediction of self-healing concrete was done based on input from chloride diffusion tests. Self-healing of cracks with encapsulated polyurethane precursor formed a partial barrier against immediate ingress of chlorides through the cracks. Application of self-healing concrete was able to reduce the chloride concentration in a cracked zone by 75% or more. As a result, service life of steel reinforced self-healing concrete slabs in marine environments could amount to 60–94 years as opposed to only seven years for ordinary (cracked) concrete. Subsequent life cycle assessment calculations indicated important environmental benefits (56%–75%) for the ten CML-IA (Center of Environmental Science of Leiden University–Impact Assessment) baseline impact indicators which are mainly induced by the achievable service life extension.

Pub.: 23 Dec '16, Pinned: 28 Aug '17