Preliminary study of the mechanical and hygrothermal properties of hemp-magnesium phosphate cements: Fid-Bau Portal

Preliminary study of the mechanical and hygrothermal properties of hemp-magnesium phosphate cements

del Valle-Zermeño, R. / Aubert, J.E. / Laborel-Préneron, A. / Formosa, J. / Chimenos, J.M.

Highlights • A new hemp-magnesium phosphate cement (heMPC) was developed and assessed. • HeMPC can incorporate higher hemp amounts with enhanced mechanical properties. • It can achieve a σ max =0.714±0.11MPa with a 20wt.% of hemp content. • It also presented enhanced thermal properties (λ D =0.103W·m⁻¹ ·K⁻¹). • The improved performance is attributed to the effective formation of K-struvite.

Abstract The use of bio-based materials in the construction field is of great interest to society and the scientific community because of its highly sustainable character. They are formed by plant fibres and a binder, usually cement, lime or pozzolanic additives. Among the new vegetable fibres used, hemp-based biomaterials have attracted great attention in the recent years due to its excellent thermal and hygroscopic properties. However, they present a very low mechanical performance, which has intensified the search for better alternatives. In this research, the use of magnesium phosphate cement (MPC) as binder with different hemp additions (8%, 12%, 16% and 20% by weight) was evaluated. Thus, a new material made of hemp and MPC (heMPC) was developed. According to the results obtained, the heMPC could be used in floor or pre-cast structural applications since it presented enhanced mechanical (σ max =0.714±0.11MPa with a 20wt.% of hemp content) and thermal (λ D =0.103W·m⁻¹ ·K⁻¹, density=600kg·m⁻³) properties with respect other lime-based hemp biomaterials. Furthermore, the material exhibited good hygroscopic properties (water absorption by capillarity). Accordingly, this preliminary study allowed opening a new research line in the use of hemp bio-composites, in which other important properties are currently under investigation. The MPC used as a binder in this study was formulated with a by-product from the MgO industry, which increases the sustainability and recyclability criteria of the material developed.