Development of Eco-friendly and High-Strength Lime-Hemp Concrete (LHC)
Notice bibliographique
Résumé
There is a growing demand for eco-friendly alternatives to Portland cement (PC) in the construction industry, primarily driven by the global push to achieve net-zero carbon emissions by 2050. Lime-hemp concrete (LHC), or hempcrete, presents a promising solution to replace traditional, carbon-intensive Portland cement (PC) based construction materials. However, its adoption has been constrained by its limited mechanical strength, with compressive strength ranging from approximately 0.4 to 3.2 MPa and flexural strength ranging from 0.06-1.2 MPa depending on dry density, as reported in several studies. Despite its impressive net carbon-negative potential (around -135 kg CO₂/m³) and other remarkable properties, this limitation has hindered its widespread appeal within the construction industry. This study focuses on developing LHC, with improved mechanical strength while maintaining its advantageous properties, including breathability, insulation, and hygrothermal performance. By incorporating Polyvinyl Acetate (PVAc) adhesive into the LHC system, we developed a mix with a weight ratio of 1:0.3:0.3:0.6 of lime, hemp stalk particles (SP), PVAc, and water. This resulted in a relatively high 28-day compressive strength of 9.9 ± 0.31 MPa and a flexural strength of 5.0 ± 0.25 MPa, demonstrating promising potential for further improvement to make it suitable for load-bearing applications in the future. The optimized LHC has a dry density of 841.61±5.22 kg/m³, dry thermal conductivity of 0.061±0.0006 W/mK, dry specific heat capacity of 1883.38 J/kgK, vapor permeability of 47.83 perm-inch, and a Moisture Buffer Value (MBV) of 1.50 g/m²%RH. Later, a composite wall block was designed based on this mix for further improvement of thermal and hygrothermal properties, which achieved a vapor permeability of 60.65 perm-inch, thermal conductivity of 0.050±0.00145 W/mK, and an MBV of 1.35 g/m²%RH. In the second phase of this project, calcined tailings from the Tailing Solvent Recovery Unit (CTSRU) were used as a lime replacement material (LRM), replacing 30 wt.% of the lime. This approach could reduce the carbon footprint, cost and environmental impact of the developed LHC further by replacing a significant portion of lime with waste calcined tailings. The substitution not only mitigated the environmental impact associated with the replaced lime production and tailings management but also preserved comparable mechanical performance, attaining a compressive strength of 9.3 ± 0.85 MPa at a dry density of 939.44 ± 11.20 kg/m³. This indicates that the material retained its mechanical performance despite the use of waste materials as LRM component. According to our study, X-ray diffraction (XRD) and differential thermogravimetric (DTG) analyses showed no significant pozzolanic activity in CTSRU, as no pozzolanic reaction products were observed in XRD or increased portlandite consumption by DTG analysis. Therefore, it is considered an LRM rather than a supplementary cementitious material (SCM), which requires notable pozzolanic or hydraulic activity. The comparable strength in the presence of 30 wt% CTSRU was attributed to pore refinement, evidenced by reduced porosity, a denser microstructure, a change in pore types, reduced microcracking, and enhanced interfacial adhesion between lime-hemp particles, as confirmed by X-ray computed tomography (X-CT) and scanning electron microscopy-energy dispersive X-ray (SEM-EDS) analyses. The composite wall block made from LHC core with CTSRU achieved a dry thermal conductivity of 0.052±0.000124 W/mK, vapor permeability of 44.38 perm-inch, and an MBV of 1.28 g/m²%RH. X-CT imaging revealed around 50% porosity in the composite, while SEM-EDS analysis confirmed a denser microstructure with CTSRU. This research highlights the potential of LHC as a high-strength material with improved mechanical and hygrothermal performance, offering an eco-friendly alternative for Portland cement-based wall blocks in the future, especially as load-bearing wall applications.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».