Moisture conditions in a Dutch tunnel lining and possible consequences for reinforcement corrosion

Title: Moisture conditions in a Dutch tunnel lining and possible consequences for reinforcement corrosion
Author(s): J.H.M. Visser
Paper category : conference
Book title: International RILEM Conference on Advances in Construction Materials Through Science and Engineering
Editor(s): Christopher Leung and K.T. WAN
ISBN: 978-2-35158-116-2
e-ISBN: 978-2-35158-117-9
Publisher: RILEM Publications SARL
Publication year: 2011
Pages: 586 - 593
Total Pages: 8
Nb references: 14
Language: English

Abstract: All drilled tunnel in the Netherlands are required to have a service life of 100 years. For the first drilled tunnel, the Second Heinenoord Tunnel, a conventional design was made on the basis of ‘best current practice’. Later, a probabilistic redesign was made but it proved difficult to assess the exact failure modes. It was assumed that onset of corrosion was due to chloride penetration at the exterior reinforcement and at leaking joints and due to carbonation at the interior reinforcement. On this basis, corrosion was predicted to occur already after five years of service at those locations that were damage during construction. However, no other measures were taken than conventional repairs of those spots.
Since 1997, much insight has been obtained how to design for durability. In this paper, a first step in a re-evaluation of the service life is made for the Second Heinenoord tunnel by assessment of the major environmental loads on the lining and the consequential moisture distribution and transport. From the analysis it is expected that the moisture conditions in the tunnel lining establish in equilibrium with the relative humidity of the interior. Initially, this equilibrium is reached by suction, which can be completed within short time. With the water load on the exterior serving as an impervious boundary (pressure flow being negligible), the relative humidity in the concrete lining then is constant throughout. The degree of saturation of the concrete will establish in equilibrium with its internal local relative humidity.
With the ground water containing no chlorides and the water penetration being negligible, no corrosion of the exterior reinforcement is expected. With the relative humidity of the interior being relatively low, carbonation of the concrete is expected to occur and may result in corrosion at the interior reinforcement. In addition, the condition for chloride penetration from de-icing salts is also favorable from the interior, but need to be addressed in more detail.

Online publication: 2011-10-31
Publication type : full_text
Public price (Euros): 0.00

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