Relation between mass flow in cement-based composite materials and durability, investigated by means of neutron imaging

Author(s): F.H. Wittmann, P. Zhang, T. Zhao
Paper category: Conference
Book title: Concrete Repair, Rehabilitation and Retrofitting III (ICCRRR)
Editor(s): M.G. Alexander, H.-D. Beushausen, F. Dehn, P. Moyo
Print ISBN: 978-0-415-89952-9
Publisher: Taylor & Francis Group
Pages: 170 – 171
Total Pages: 2
Language: English

Abstract: 
Mass flow is at the origin of most important deteriorating processes in cement-based composite materials such as mortar and concrete. Water and aqueous solutions can be absorbed by capillary action into the pore space deep and quickly. Pure water leads to leaching and chemical compounds dissolved in water such as sulfates and ammonia can weaken and finally destroy the cement-based matrix by chemical reactions. Chloride dissolved in water can be transported deep into the pore space of concrete by convection and at a later stage even deeper by diffusion. If a critical amount of chloride is accumulated near the steel reinforcement corrosion may be initiated. Neutron imaging is a powerful method to visualize and to determine quantitatively the mass flow in porous materials such as bricks stones and concrete. This advanced method has been applied to study capillary absorption of water and aqueous salt solutions into concrete. The moisture movement into cracks has been studied in particular. It has been shown that water repellent impregnation of the surface of concrete slows down significantly ingress of water and of dissolved aggressive compounds transported with the penetrating water by convection during capillary absorption. Damage caused by frost action accelerates capillary absorption and chloride penetration.

Online publication: 2014
Publication Type: abstract_only
Public price (Euros): 0.00