Cleaning of Concrete Fouled by Algae with the Aid of Thiobacilli

Title: Cleaning of Concrete Fouled by Algae with the Aid of Thiobacilli
Author(s): B. De Graef, J. Dick, W. De Windt, N. De Belie, W. Verstraete
Paper category : conference
Book title: Second International RILEM Workshop on Microbial Impact on Building Materials
Editor(s): M. Ribas Silva
Print-ISBN: None
e-ISBN: 2912143845
Publisher: RILEM Publications SARL
Publication year: 2004
Pages: 55 - 64
Total Pages: 10
Nb references: 12
Language: English

Abstract: Concrete specimens weathered for over a decade in the Belgian moderate climate, showing a black organic outer layer, mainly consisting of algae, were cleaned with a new biological technique. It consists of the application, either by sprinkling or by submersion, of a mixture of sulphur oxidising bacteria of the genus Thiobacillus supplemented with an appropriate nutrient. The aim of the cleaning technique is to remove the fouled layer in such a way that the surface is uniformly cleaned. The general effect of the technique was documented by the use of colorimetry and
microscopy. Two sets of weathered concrete samples containing blast furnace slag cement or ordinary portland cement were investigated.
Differences in the effectiveness were seen on concrete samples of a different cement type. The effect on the ordinary portland cement concrete samples was in some cases up to 100% stronger than the result on the blast furnace slag cement samples. The sprinkling treatment is about 50% as effective as the submersion treatment.
A side effect was the formation of a gypsum layer on some of the specimens, resulting in a whiter appearance.

Online publication: 2004-06-25
Publication type : full_text
Public price (Euros): 0.00