Migration of water through cracked textile, reinforced concrete applied as a protective layer for RC structures

Author(s): M. Lieboldt, C. Schröfl, V. Mechtcherine
Paper category: Conference
Book title: 2nd International conference on Microstructural-related Durability of Cementitious Composites
Editor(s): Guang Ye, K. Van Breugel, Wei Sun, Changwen Miao
Print ISBN: 978-2-35158-129-2
e-ISBN: 978-2-35158-123-0
Publisher: RILEM Publications SARL
Pages: 440-449
Total Pages: 9
Language: English

Abstract: 
Understanding the transport of liquids in and through concrete is essential to an assessment of its durability. The research at hand presents insights into the transport mechanisms of water in and through composite concrete specimens made of a cracked ordinary concrete (OC) as a substrate and textile reinforced concrete (TRC) as a cover layer for its strengthening and repair. The TRC cover layer was assessed with regard to its efficiency as a protective layer against the ingress of water. Since in real applications such TRC layers may actually be or presumed to be cracked, thereby activating the load-carrying function of the textile reinforcement, the TRC layer was cracked for purposes of this study. The water transport in the OC specimens without TRC layer was used as reference. Neutron radiography served as the main testing technique.
It was found that water entered very quickly into the OC through its macro-cracks; migration continued by capillary transport into the matrix via the cracks and the wetted specimen surface. The water-front reached the depth of 60mm within 6 hours and saturation was observed after 23 hours. The specific crack pattern of the TRC with numerous but very narrow cracks resulting from tensile loading affected the water migration in the composite specimen fundamentally. The TRC layer (thickness 14mm) was saturated after as long as 6 hours. From then on, a horizontal water-front migrated into the cracked OC. Due to the low transport rate the macro-cracks could not activate their intense suction force, although the water migrated only by capillary suction through the OC matrix. After 23 hours, the depth of the water-front in the OC substrate was only approximately 15mm.
Additionally, the permeability of the cracked TRC material was investigated by means of water and oxygen permeation tests. Furthermore, the effect of self-healing phenomena on the transport properties of TRC was investigated. The self-healing of the fine cracks led to a very pronounced reduction in the transport rates over time.

Keywords: textile reinforced concrete, multiple cracking, water transport, neutron
radiography, self-healing

Online publication: 2013
Publication Type: full_text
Public price (Euros): 0.00