Variability of the mechanical properties of hemp concrete

•This study is focused on statistical analysis of hemp concrete properties.•The main objective is to determine statistically the variability of the three main properties, which are: material density, compressive strength and Young’s modulus.•Two types of hemp shiv have been used with two batches for each type.•Three probability distributions, namely: normal, log-normal and Weibull, have been proposed to fit the experimental results.•There is an accurate repeatability for compressive strength and dry density.•The results for Young's modulus are of a large variability.•The mixing procedure must be done with an utmost care.•The impact of initial water content on the density has been also highlighted.•The hemp with small particle sizes leads to better mechanical properties of hemp concrete. The focus of this study is on statistical analysis of hemp concrete properties. The main objective is to determine statistically the variability of the three main properties, which are: material density, compressive strength and Young’s modulus. The analysis is done with respect to four main parameters, namely: the testing laboratory equipment and procedure, the hemp shiv type, the batch elaboration and finally the specimen size. Two types of hemp shiv have been used with two batches for each type. Two cylindrical specimen sizes have been considered: 11×22cm and 16×32cm. All the specimens were manufactured and dried in the same laboratory in order to ensure the repeatability and homogeneity of studied material. After 90 days of drying under the same conditions, the specimens were transported to ten different laboratories for compressive testing. Before testing, a drying protocol during 48h was applied by all laboratories for all specimens. Then, a unique protocol for compressive testing has been applied using the compressive testing machine in each laboratory. Finally, all data have been collected for statistical analysis. In this study, the results obtained by different laboratories show low variability for compressive strength and dry density; which is not the case for Young's modulus. Three probability distributions, namely: normal, log-normal and Weibull, have been proposed to fit the experimental results.