Water transfers in hemp concrete followed by nuclear magnetic resonance

Abstract

Hemp is used as an aggregate in hemp concrete, which is mainly constituted of hemp, cement, lime and water. As hemp is known to have a good affinity to water, it is important to understand its water uptake capacities. NMR relaxometry measurement allowed us to follow the kinetics of imbibition of water in hemp. Our results show that imbibition develops progressively over three days, which is far more than we can expect for porous media, even with nanopores. Then, water transfers between the different phases of hemp concrete were followed by NMR measurements. Due to the very different values of the NMR relaxation times of water in hemp and in the binder, we were able to observe the transfer of water from hemp to binder during the first week of setting.