Impacts of alkalinity and environmental ageing on fungal growth in hemp concretes
Résumé
Hemp concrete is a building insulation material based on vegetal aggregates and a mineral binder. Due to the lignocellulosic constitution of this material and to the amount of fungi naturally present in hemp, concerns exist about risks of fungal growth, which induce deterioration of the material but also indoor air pollution. In this paper, we focus on the fungal origin on hemp concrete and the fungal growth during
ageing. Firstly, the comparison between the fungi population in aggregates and in fresh hemp concrete is done to investigate the capacity of the pH to kill spores present in the material. Secondly, fungal population in concrete is followed for 18 months under a static (50%RH-20°C) and dynamic (variation between 98 and 40% RH - 30°C) ageing protocols. For fresh hemp concrete, the fungal population remains important, despite the alkalinity of the binder. After ageing, no fungal growth is observed, which is explained by the low RH% of the static ageing and of the drying step coupled with the mineralization of vegetal aggregates in the dynamic ageing. Based on these results, no fungal growth should appear in real buildings if the material is well manufactured and without exterior damage.
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