Assessing the impact of calculation methods on the variability of Young’s modulus for hemp concrete material

• Published in: Construction & building materials Vol. 198; pp. 332 - 344
• Main Authors: Niyigena, César, Amziane, Sofiane, Chateauneuf, Alaa
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 20-02-2019; Reed Business Information, Inc. (US)
• Subjects: Analysis; Concretes; Hemp concrete; Mechanical properties; Variability; Young's modulus; France; Hemp concrete; Young's modulus; Variability
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2018.11.174

•Hemp concrete rigidity is assessed using different methods: floating, cyclic, etc.•Three types of modulus – apparent, elastic and hardening modulus – are determined.•Tendency of floating method to overestimate the modulus values has been highlighted.•It is highlighted that cyclic method tends to underestimate modulus with low values.•Thanks to its low dispersion, the floating method is better suited for such material.
Parameters influencing the variability of Young’s modulus for hemp concrete include, among others, the method by which it is calculated. At present, a range of methods are available in the literature, but as yet, little is known about how they might affect the obtained results, given that hemp concrete is a highly sensitive material. For the in-depth study of this issue presented herein, the Young’s modulus properties of two formulations of hemp concrete are analysed. Three main types of modulus – apparent, elastic and hardening modulus – are determined, using different calculation methods: floating, tangential, cyclic and hardening with 5 strategies. Therefore, for a stress–strain curve with 3 loading/reloading cycles, a total of 38 modulus values are calculated. Using the aforementioned methods, a comparative study of the results at 60, 90 and 180 days on 5 specimens for each formulation and each age reveals that the cyclic modulus method gives low values and the tangential modulus method gives medium values, while the floating modulus method gives higher values. In this latter case, low dispersion is observed, making this method more suitable to calculate hemp concrete’s modulus.