Matériaux & Techniques
Volume 78, Number 12, 1990
|Page(s)||59 - 64|
|Published online||13 April 2017|
Evaluation of the cement degradation induced by the metabolic products of two fungal strains
1 Centre d’Études Nucléaires de Fontenay aux Roses
2 Centre d’Études Nucléaires de Cadarache
During their metabolism, the microorganisms can produce acids able to induce the degradation of cement. Two acidifying but alkalophilic fungal strains have been isolated from a soil sample. One is an Aspergillus strain which produces gluconic and oxalic acids. These acids induce (after eleven months of contact) a dissolution of portlandite (with a low leaching of calcium), an increase in the cement porosity (+ 11.4 %), a loss of the bending strength (— 78 %). The second strain, a Mycelia sterila produces gluconic and malic acids, responsible (during the same period) for a very important dissolution of portlandice (with a leaching of calcium : 4.2 % of the initial content), an increase in the porosity (+ 11 % also), and a loss of the bending strength less important than in the other case (— 62 %). The direct contact of mycelia with the cement does not increase the effects of the acids. A low pH and a high temperature favour the acids production.
© SIRPE 1990
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