Influence of nanomaterials on properties of lime and hemp/lime composites for energy efficient wall design

ABSTRACT

A mixture of thermal, porosity and compressive strength properties of lime based materials were determined after adding different percentages of nanomaterials to enhance performance (nSiO₂, nClay and nZnO). Specimens were formulated for use in the design of a five layer energy efficient wall. Materials consisted of lime nanocomposites (used as ‘Renders’, properties determined were thermal conductivity (λ) and porosity) and lime/hemp shiv nanocomposites for thermal isolation (‘Insulators’, λ). A lime/hemp fibre nanocomposite, with PVAc glue for strength, was developed as a load bearing material (‘Core’, λ, strength). A solvent exchange method for drying the specimens was applied as soon as practically possible to investigate if rapid drying could be considered without adverse effects. Results showed that the maximum 28 day decrease in λ for the Render was by using 4% nZnO, λ being −18% compared to the control sample. The same render also exhibited the lowest density. For the Insulator, λ was −31% when also using 4% nZnO in comparison to the nanofree specimen. Strength of the Core exceeded 10 MPa, much greater than the minimum load bearing requirement. The paper concludes by comparing the U value of a wall utilizing these findings to those from an existing lime/hemp design.

KEYWORDS:

• Nanomaterials
• nanocomposites
• hemp shiv
• hemp fibre
• thermal conductivity

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

F.J. O’Flaherty http://orcid.org/0000-0003-3121-0492

F.J. Khalaf http://orcid.org/0000-0002-5643-8437

V. Starinieri http://orcid.org/0000-0002-7556-0702

Additional information

Funding

This work was supported by the Iraqi Ministry of Higher Education and Scientific Research and Iraqi Cultural Attaché in London, who supported the research studies for Faraj Khalaf. Khalaf is a joint lead author of this paper.