Durability of hemp concretes exposed to accelerated environmental aging

This study examines the evolution of the functional properties of two hemp concretes formulated with two different binders over 2 years in different environmental conditions. Stable environmental conditions (50% RH - 20 degrees C) have been applied to hemp concretes to obtain the reference aging A(REF). An accelerated aging process A(WD) is chosen, consisting of cycles of wetting and drying. In relation to the reference aging, no significant variation of the chemical, microstructural and functional properties is observed, whether in terms of the thermal, acoustic, hydric or mechanical behavior. During accelerated aging, variations of properties are observed: an increase of thermal conductivity, and water vapor sorption capacity for both binders and a decrease of acoustic performance for the lime-based binder. No variation of mechanical properties is observed. These results are linked to alterations of the chemical and microstructural properties: hydration and carbonation of the binder, mineralization, swelling and shrinkage and consumption of vegetal walls by micro-organisms. By comparing these results with measurements carried out under real conditions, this work shows that the performance of hemp concretes should remain stable for several years. (C) 2020 Elsevier Ltd. All rights reserved.