## 4 Conclusions  
To investigate the release of plant cell wall components during the formulation of agro-based concrete and binderless particle boards, several liquid extractions were performed, varying in pH and temperature. Two types of hemp shiv, \"HS1\" and \"HS2\", were selected based on their behavior observed in previous studies [11; 12; 13]. HS1 is known to release a high quantity of extractives, which poses challenges in the formulation of agro-based concrete but may offer beneficial properties for binderless particle boards. In contrast, HS2 releases fewer extractives, making it more suitable for agro-based concrete applications, while it may be less advantageous for binderless particle boards. In this study, both hemp shiv types were analyzed, revealing notable differences in their behavior and extractive release, as outlined below:  
* Van Soest analysis indicated that HS2 contains a higher rate of lignin compared to HS1, while HS1 has a higher concentration of soluble compounds. - Microbial activity was slightly higher in HS2 than in HS1. - Mass loss and pH changes varied significantly between HS1 and HS2. At first, the increase in temperature (50 \({}^{\circ}\)C or 100 \({}^{\circ}\)C) led to a decrease in pH for HS1, while an unexpected pH rise was observed for HS2. For \"agro-based concrete\" simulation, NaOH was found to be a more effective extraction agent than Ca(OH)2. The combined effects of pH and temperature did not significantly increase mass loss but did facilitate the release of extractive compounds. HS1 generally released more extractives than HS2, except under conditions using Ca(OH)2, regardless of temperature. However, for the \"binderless particle board\" simulation, similitude was observed between hemp shiv, although a raise in pH units was found for HS2. The effect of temperature slightly increased the mass loss for hemp shiv, while HS1 released more compounds than HS2. - The pH decreased during the alkaline extraction simulation of \"agro-based concrete\", suggesting the release of acidic molecules potentially from sugar degradation (e.g., lactic acids) or polyphenols (e.g., hydroxycinnamic acids). - Physical and Microscopic Analysis:
- Density measurements and SEM analysis revealed no significant differences between HS1 and HS2. - XRD and BET analyses showed minimal differences between HS1 and HS2, except for HS2 at 100 \({}^{\circ}\)C for the \"binderless particle board\" simulation, where there was a decrease in the specific surface area and a tendency for reduced cellulose
crystallinity. On the other hand, in the \"agro-based concrete\" simulation, a huge difference was observed between NaOH and Ca(OH)\({}_{2}\) without temperature contribution. This study highlights the inherent variability of plant-based materials, which can lead to inconsistencies in their performance and properties. This variability is a significant challenge in the formulation of agro-based materials, where uniformity is often desired for predictable physical performances. This work provides insights into the liquid extraction processes and their effects on hemp shiv, but it is important to acknowledge the following limitations:  
* This study primarily addresses liquid extraction parameters (pH, temperature), but overlooks key factors like pressure and humidity, which are crucial in binderless particle board performance and extractive compound release [29]. * When plant materials are used in Portland cement, crystalline phases formed during hydration can modify plant cell wall structures, potentially altering the type of extractives released [20]. * The release of extractive compounds during processing affects the properties of agro-based materials. Thus, controlling this release is vital to optimize performance. * The variability in extractives between different plant samples, and even within the same agro-resource like hemp, suggests the need for a tailored approach and pretreatment processes to standardize materials before application [56].