Experimental investigations of combined sulphate and acid attack on concrete by oxidation of iron disulphide

Title: Experimental investigations of combined sulphate and acid attack on concrete by oxidation of iron disulphide
Author(s): B. Siebert, R. Breitenbuecher
Paper category : conference
Book title: International Conference on Microstructure Related Durability of Cementitious Composites
Editor(s): W. Sun, K. van Breugel, C. Miao, G. Ye and H. Chen
Print-ISBN: 978-2-35158-065-3
e-ISBN: 978-2-35158-084-4
Publisher: RILEM Publications
Publication year: 2008
Pages: 393 - 402
Total Pages: 10
Nb references: 9
Language: English

Abstract: In the past uncertainties were raised in practice by several damages in concrete structures, which are in direct contact with soils containing iron disulphides. During oxidation processes of iron disulphides initiated e. g. by excavation during construction measures products like sulphate and sulphuric acid are released that are very aggressive to cementitious materials.
The single attacks of sulphate or acid on concrete with their mechanisms have been extensively investigated and are separately well understood. However, there is still a lack of knowledge about the mechanisms that damage concrete by a combined attack. This question is investigated currently at the Institute for Building Materials at the Ruhr-Universität Bochum.
The experimental tests focus on the transport process of both sulphate and acid into the concrete and on the subsequent evolution of the corresponding damage process in the microstructure.
For that purpose concrete specimens varying in different parameters e. g. type of cement, curing etc. are embedded in adequate sulphate and acidic solutions as well as in iron disulphidic soils at 8 °C. By means of appropriate test methods like SEM-analysis on thin sections in combination with EDX-analysis the degradation process of concrete is investigated after different periods within two years.
The results after one year of storage in the test solutions show a characteristic formation of corrosion zones in the cross-section of the concrete specimens. The appearance including the chemical composition and thickness of the respective zones depend in the first instance on the the pH-value and secondarily on the sulphate concentration.

Online publication: 2009-06-09
Publication type : full_text
Public price (Euros): 0.00