Microstructural Characterization of Prefabricated Hempcrete Blocks

Abstract:

Sustainable building materials have been developed to reduce the polluting emissions and the exploitation of natural resources of the building sector. Among these materials, an outstanding category is that of nature-based solutions which are produced recovering waste or by-products of agricultural cultivations and using them as vegetal aggregates to replace the traditional ones. This paper focusses on hempcrete which is produced mixing the by-product of industrial hemp cultivation (i.e., shives) and lime to obtain a sustainable, breathable and insulating material. The strength of hempcrete develops through carbonation of the binder that, leading to the formation of calcium or magnesium carbonates and mineralization of shives, determines the microstructure and hence most of the characteristic properties of the material. The aim of this research is to investigate how carbonation influences the microstructure of hempcrete when different recipes are used for blocks production. This study consists in the characterization of the material through techniques such as XRD (X-ray Diffractometry), SEM (Scanning Electron Microscopy) and TG-DTG (thermogravimetric analyses). Moreover, the evolution of carbonation is studied analyzing samples at different maturation times. The investigation of the carbonation reaction degree is also crucial to evaluate the environmental performances of the material because it allows the quantification of the carbon dioxide uptake. Also, periodic characterization allows to assess the durability of hempcrete and to select the best formulation according to the designed application and the corresponding service conditions.

• Periodical: Construction Technologies and Architecture (Volume 1)
• Pages: 388-394
• DOI: https://doi.org/10.4028/www.scientific.net/CTA.1.388
• Online since: January 2022
• Authors: Chiara Moletti*, Valeria Arosio, Giovanni Dotelli
• Keywords: Blocks, Carbonation, Characterization, Hemp, Hempcrete

References

[1] Arrigoni, A., Panesar, D. K., 2019. Opportunities for reducing greenhouse gas emissions of insulation materials in Canada after cannabis legalization, in: Proceedings of the 3rd International Conference on Bio-Based Building Materials. Presented at ICBBM 2019, RILEM, Belfast, pp.626-631. https://doi.org/10.26168/icbbm2019.88.

[2] Arrigoni, A., Pelosato, R., Melià, P., Ruggieri, G., et al., 2017. Life cycle assessment of natural building materials: the role of carbonation, mixture components and transport in the environmental impacts of hempcrete blocks. Journal of Cleaner Production, 149, 1051–1061. https://doi.org/10.1016/j.jclepro.2017.02.161.

DOI: 10.1016/j.jclepro.2017.02.161

[3] Beaugrand, J., Berzin, F., 2013. Lignocellulosic fiber reinforced composites: Influence of compounding conditions on defibrization and mechanical properties. Journal of Applied Polymer Science, 128(2), 1227–1238. https://doi.org/10.1002/app.38468.

DOI: 10.1002/app.38468

[4] Chabannes, M., Garcia-Diaz, E., Clerc, L., Bénézet, J. C., 2015. Studying the hardening and mechanical performances of rice husk and hemp-based building materials cured under natural and accelerated carbonation. Construction and Building Materials, 94, 105–115. https://doi.org/10.1016/j.conbuildmat.2015.06.032.

DOI: 10.1016/j.conbuildmat.2015.06.032

[5] Elfordy, S., Lucas, F., Tancret, F., Scudeller, Y., Goudet, L., 2008. Mechanical and thermal properties of lime and hemp concrete (hempcrete,) manufactured by a projection process. Construction and Building Materials, 22(10), 2116–2123. https://doi.org/10.1016/j.conbuildmat.2007.07.016.

DOI: 10.1016/j.conbuildmat.2007.07.016

[6] Ingrao, C., Lo Giudice, A., Bacenetti, J., Tricase, C., et al., 2015. Energy and environmental assessment of industrial hemp for building applications: A review. In Renewable and Sustainable Energy Reviews. https://doi.org/10.1016/j.rser.2015.06.002.

DOI: 10.1016/j.rser.2015.06.002

[7] Ip, K., Miller, A., 2012. Life cycle greenhouse gas emissions of hemp-lime wall constructions in the UK. Resources, Conservation and Recycling, 69, 1–9. https://doi.org/10.1016/j.resconrec.2012.09.001.

DOI: 10.1016/j.resconrec.2012.09.001

[8] Jami, T., Karade, S. R., Singh, L. P., 2019. A review of the properties of hemp concrete for green building applications. In Journal of Cleaner Production. https://doi.org/10.1016/j.jclepro.2019.117852.

DOI: 10.1016/j.jclepro.2019.117852

[9] Lawrence, M., 2015. Reducing the environmental impact of construction by using renewable materials. Journal of Renewable Materials, 3(3), 163–174. https://doi.org/10.7569/JRM. 2015.634105.

DOI: 10.7569/jrm.2015.634105

[10] Murphy, R. J., Norton, A., 2008. Life Cycle Assessments of Natural Fibre Insulation Materials Final Report. 11th International Conference on Non-Conventional Materials and Technologies, NOCMAT 2009, February, 79.

[11] Villagrán-Zaccardi, Y. A., Egüez-Alava, H., De Buysser, K., Gruyaert, E., et al., 2017. Calibrated quantitative thermogravimetric analysis for the determination of portlandite and calcite content in hydrated cementitious systems. Materials and Structures/Materiaux et Constructions, 50(3). https://doi.org/10.1617/s11527-017-1046-2.

DOI: 10.1617/s11527-017-1046-2