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On the service life modelling of Tasmanian concrete bridges

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McGee, Rodney W.(Rodney William) (2001) On the service life modelling of Tasmanian concrete bridges. PhD thesis, University of Tasmania.

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Abstract

Various forms of concrete have been used for buildings since the time of Egyptian
civilisation. The art of cement manufacture was however lost during the Middle Ages.
The rediscovery of the art in the nineteenth century and the subsequent development
of reinforced and prestressed concrete have seen concrete become the most commonly
used construction material throughout the world.
While concrete structures perform well in many situations, lack of durability in others
over the last two or three decades in particular has emerged as a significant issue for
asset owners internationally. While there is a number of mechanisms by which
concrete deteriorates, chloride induced corrosion of bridge and marine structures and
carbonation induced damage of buildings are perhaps the most significant.
The various concrete deterioration mechanisms and, to a lesser extent, cover to
reinforcement have been researched and reported extensively, particularly in the last
twenty years. The research has however tended to focus on specific aspects of the
durability performance of concrete structures.
From an asset owner's perspective, it is the interaction of the various aspects of the
deterioration processes that determines management strategies for affected structures
and code and specification requirements for new structures. The literature relating to
the interaction of the chloride and carbonation deterioration mechanisms and cover to
reinforcement is however limited.
The Tasmanian Department of Infrastructure, Energy and Resources is responsible for
the management of a substantial bridge asset with a high proportion of its value in
close proximity to salt water. The durability of its concrete structures is a significant
management issue. A series of corrosion investigations and structural surveys have
provided a substantial body of data which has been analysed and reported in this thesis
to assist with the management of the asset and provide the basis for enhancements to
specifications and codes.
This work has highlighted the high variability in the parameters used to describe the
durability related properties of in situ aged concrete and in cover to reinforcement.
The high variability leads to high probabilities of corrosion initiation, particularly for chloride induced corrosion, that are reflected in the durability related performance of
the bridge asset. A high and continuing demand for maintenance, rehabilitation and
replacement of corrosion affected structures is indicated.
The high variabilities also suggest that incremental changes to existing approaches to
durability in aggressive environments will not achieve the improvements in
performance required to increase materials related reliability to levels that are
consistent with, albeit lower than, levels of structural reliability. Approaches to
enhance the durability, reflecting the significant level of change required, of concrete
structures are proposed.

Item Type: Thesis (PhD)
Keywords: Bridges, Concrete, Bridges, Concrete, Bridges, Concrete
Copyright Holders: The Author
Copyright Information:

Copyright 2001 the Author - The University is continuing to endeavour to trace the copyright
owner(s) and in the meantime this item has been reproduced here in good faith. We
would be pleased to hear from the copyright owner(s)

Additional Information:

Thesis (Ph.D.)--University of Tasmania, 2001. Includes bibliographical references

Date Deposited: 19 Dec 2014 02:58
Last Modified: 11 Mar 2016 05:54
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