Performance based laboratory methods for testing concrete degradation in aggressive aqueous solutions

Author(s): N. De Belie
Paper category: Workshop
Book title: International RILEM Workshop on Performance Based Evaluation and Indicators for Concrete Durability
Editor(s): V. Baroghel-Bouny, C. Andrade, R. Torrent, K. Scrivener
ISBN: 978-2-912143-95-2
Pages: 267 - 276
Total Pages: 10
Language: English

Abstract: 
For testing concrete performance in aggressive aqueous environments, reliable and semi-automated test procedures were developed. Two specific methods are presented here: the testing apparatus for accelerated degradation tests (TAP) to examine the degradation of concrete by aggressive chemicals; and a microbiological procedure to simulate biogenic sulfuric acid (BSA) corrosion.

With the TAP it was chosen to attain acceleration of the deterioration process through alternate wetting and drying, because this procedure simulates certain real-life situations. This is achieved by an experimental setup with concrete cylinders that rotate through containers with the test solutions. Cycles of chemical attack are followed by abrasion using rotary brushes. The change in dimension of the concrete specimens and the surface roughness are determined through a non-contact distance measurement with laser sensors. To illustrate the test procedure, experimental results concerning sulfuric and lactic/acetic acid degradation are presented.

To take into account the action of the Thiobacilli bacteria in the biogenic sulfuric acid corrosion process, a simple and reproducible microbiological test method was developed. It consists of 17-day cycles, including H₂S-incubation, incubation in a biological sulfur suspension containing elemental sulfur, biomass and biopolymers on a rotary shaker, rinsing and drying. After every cycle, the thickness and surface roughness of the concrete blocks are measured with a high precision laser beam, mounted on an automated laser measurement table (ALM). Additionally, the material losses can be determined by weighing the samples after oven drying. This method was already used to examine the BSA resistance of several commercially available and new concrete types for cement based sewer pipes.

Online publication: 2007
Publication Type: full_text
Public price (Euros): 0.00