Modeling and optimization of the mechanical and acoustic properties of hemp-hurds cement boards

Hemp-hurd Cement Boards (HHCBs) are emerging as a sustainable alternative to traditional building materials due to their eco-friendly nature and favorable mechanical and acoustic properties. Despite their environmental and acoustic potential, the use of hemp-hurds cement boards remains limited due to the lack of predictive models and optimized formulations ensuring balanced mechanical and acoustic performance. The objective of this study is to model and optimize the mechanical, thermal, and acoustic properties of HHCBs by identifying the key formulation and processing parameters governing their behavior. An experimental computational methodology was employed, combining laboratory testing with statistical modeling tools. Mechanical properties were evaluated using a Zwick/Roell universal testing machine, open porosity was measured with a PHI-X Mecanum system, airflow resistivity was determined using a SIGMA Mecanum device, acoustic performance was assessed via impedance tube measurements, and thermal conductivity was measured using a FOX 314 SN heat flow meter. The results indicate an enhancement in thermal conductivity, sound absorption, and airflow resistivity with an increased percentage of pre-treated hemp hurds in the mixture. These values exhibited a strong linear correlation with the board density and porosity. However, the boards' modulus of rupture (MOR), a measure of the material's ability to withstand bending or stretching, was reduced with a higher percentage of pre-treated hemp hurds in the mixture. The MOR values decreased from 4.49 to 0.41 MPa, as the proportion of pretreated hemp hurds in the composite increased from 40% to 80%. Although this reduction may influence the structural integrity of the boards, the obtained values remain higher than those typically reported in the literature. Overall, the proposed modeling and optimization framework provides a robust tool for tailoring HHCB formulations to targeted performance requirements, thereby facilitating their industrial scalability, improving design reliability, and supporting the development of low-carbon, high-performance building envelope systems.