Haddad, Kamal, Lannon, Simon  ORCID: https://orcid.org/0000-0003-4677-7184 and Latif, Eshrar ORCID: https://orcid.org/0000-0003-3982-6929
2025.
Exploration of thermal and structural performance of bio-stabilised cob mixes.
Presented at: ICBBM 2025 - 6th International Conference on Bio-Based Building Materials,
Rio de Janero, Brazil,
17-20 June 2025.
Bio-Based Building Materials - Proceedings of ICBBM 2025.
RILEM Bookseries
, vol.2
Switzerland:
Springer Nature,
pp. 439-459.
10.1007/978-3-031-92874-1_36
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Abstract
This study evaluates bio-stabilised cob's structural and thermal performance for sustainable buildings. Thirty-three cob mixes were analysed: subsoil, water, and natural fibres—hemp shiv and barley straw—with fibre contents ranging from 1% to 10% and water contents ranging from 20% to 30% by volume. Unstabilised samples of subsoil and water served as baselines. X-ray diffraction revealed that the subsoil contained 70% quartz, while the fibres were predominantly cellulose. Scanning electron microscopy showed the sub-soil had a compact structure with 20% porosity, whereas hemp shiv and barley straw were more porous, with 30% and 43%, respectively. Adding fibres significantly reduced thermal conductivity compared to unstabilised mixes. The lowest thermal conductivity was 0.132 W/m·K for a mix with 7% barley straw and 30% water, while the highest was 0.378 W/m·K for the unstabilised mix with 20% water. Higher densities correlated with higher thermal conductivity. Compressive strength decreased with increased fibre content, with hemp shiv causing a smaller reduction than barley straw. The highest compressive strength was 1.719 MPa for a mix with 5% hemp shiv and 25% water; the low-est was 0.785 MPa for a mix with 7% barley straw and 25% water. Volumetric shrinkage increased with higher fibre and lower water contents. The mix with 3% hemp shiv and 30% water content demonstrated optimal performance: thermal conductivity of 0.163 W/m·K, compressive strength of 1.454 MPa, density of 1,676 kg/m³, and volumetric shrinkage of 16.4%. This research highlights the importance of analysing cob's constituents to optimise its properties, supporting cob's potential as a sustainable construction material for decarbonising the built environment.
| Item Type: | Conference or Workshop Item (Paper) |
|---|---|
| Date Type: | Published Online |
| Status: | Published |
| Schools: | Schools > Earth and Environmental Sciences Schools > Architecture Schools > Engineering |
| Subjects: | N Fine Arts > NA Architecture Q Science > QD Chemistry Q Science > QE Geology T Technology > TA Engineering (General). Civil engineering (General) |
| Publisher: | Springer Nature |
| ISBN: | 9783031928741 |
| Date of First Compliant Deposit: | 30 June 2025 |
| Last Modified: | 25 Jul 2025 14:30 |
| URI: | https://orca.cardiff.ac.uk/id/eprint/179218 |
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