Investigating the role of moisture on concrete carbonation using single-sided 1H-NMR

Author(s): Charlotte Thiel, Robin E. Beddoe, Dirk Lowke, Christoph Gehlen
Paper category: Proceedings
Book title: Proceedings on International RILEM Conference on Materials, Systems and Structures in Civil Engineering Conference segment on Moisture in Materials and Structures
Editor(s): Kurt Kielsgaard Hansen, Carsten Rode and Lars-Olof Nilsson
ISBN: 978-2-35158-178-0
e-ISBN: 978-2-35158-179-7
Publisher: RILEM Publications SARL
Publication year: 2016
Pages: 274 - 281
Total Pages: 8
Language : English

Abstract: Accelerated test methods are commonly used in order to predict concrete carbonation in natural concentrations. Here, specimens are carbonated at high CO2 concentrations at a specified temperature and relative humidity. However, the transfer of laboratory results to field behaviour remains difficult because CO2 transport is affected by the original moisture content of the specimens and additional moisture formed by the carbonation reaction.Therefore knowledge on moisture transport and content during carbonation is required.
Specimens made with Ordinary Portland cement and a water/cement ratio 0.50 were exposed to 0.05, 2 and 10 vol.% CO2 for 28 days. Single-sided NMR moisture profiles weredetermined before, during and after carbonation. It is shown that moisture content increases due to carbonation at high CO2 concentrations (greater than or equal to 10 %) in the beginning of the exposure. An increase in capillary pore water in front and behind the carbonation front could be observed even after 28d. During natural carbonation moisture changes are mainly due to the change in porosity produced by the carbonation reactions. It is shown that changes in phase composition and thus porosity dominate the carbonation process in cement-based materials. Therefore, the suitability of high CO2 concentrations is limited for an accelerated test that reflects field condition. Single-sided 1H NMR proved to be a valuable tool to investigate moisture transport in concrete non-destructively.

Online publication : 2016
Publication type : full_text
Public price (Euros) : 0.00