Degradation of concrete due to combined chemical attack by sulphuric acid and iron sulphate

Authors: B. Siebert, R. Breitenbücher
Paper category: conference
Book title: Concrete Durability and Service Life Planning – ConcreteLife’09
Editor(s): K. Kovler
Print ISBN: 978-2-35158-074-5
e-ISBN: 978-2-35158-085-1
Publisher: RILEM Publications SARL
Publication year: 2009
Pages: 204 – 212
Total Pages: 9
Language: English

Abstract: Organic-rich soils may contain iron disulphides as pyrite and marcasite. Due to aeration in the course of construction measures e. g. excavation of ground these minerals may oxidise and develop sulphuric acid as well as iron sulphate. After backfilling of excavated oxidising soil adjacent concrete surfaces as foundations may be attacked by these aggressive environmental conditions of pH-values down to 2 and sulphate concentrations of more than 10,000 mg/l. In order to investigate the mechanisms of such a combined attack and the difference towards the well-known single acid or sulphate attack experimental studies are currently carried out by the Institute for Building Materials at the Ruhr-Universität Bochum.
In long-term experiments the performance of different concretes in oxidising soils containing iron disulphides is evaluated. The transport of the oxidation products, both iron sulphate and sulphuric acid, into the concrete and the resulting damage processes in the microstructure are determined in the first instance by means of SEM- and EDX-analysis on thin sections.
After more than one year of storage in the soils the concrete specimens show severe signs of a chemical attack and have developed characteristic corrosion zones on their surfaces.

Online publication: 2012-05-16
Publication Type: full_text
Public price (Euros): 0.00