Studying the hardening and mechanical performances of rice husk and hemp-based building materials cured under natural and accelerated carbonation

Under natural carbonation, the results indicated that the lime-based binder was almost hardened in the same way for both concretes with a similar rate of carbonation. However, the rice husk concrete was characterized by a ceiling effect of mechanical performances over time, which was attributed to the lower bonding strength between rice husks and lime. Concerning specimens exposed outdoors, the strength gain over time was more significant owing to more favorable humidity conditions for carbonation. The accelerated carbonation curing led to an increase of mechanical properties of the concretes in the short term. The compressive strength after CO2 curing was approximately equivalent to those obtained after 10 months of outdoor exposure under natural carbonation.