| dc.contributor |
Vinai, Raffaele |
|
| dc.contributor |
Harper, Anna |
|
| dc.contributor |
Walker, Pete |
|
| dc.creator |
Ntimugura, F |
|
| dc.date |
2022-10-19T13:27:23Z |
|
| dc.date |
2022-09-24 |
|
| dc.date |
2022-10-19T13:07:41Z |
|
| dc.date |
2022-10-19T13:27:23Z |
|
| dc.date.accessioned |
2023-02-23T12:17:24Z |
|
| dc.date.available |
2023-02-23T12:17:24Z |
|
| dc.identifier |
ORCID: 0000-0002-6205-6929 (Ntimugura, Fabrice) |
|
| dc.identifier |
http://hdl.handle.net/10871/131334 |
|
| dc.identifier.uri |
http://localhost:8080/xmlui/handle/CUHPOERS/258671 |
|
| dc.description |
The reduction of greenhouse gas emissions towards net zero carbon, through the efficient use of resources, is among the grand challenges. Buildings offer an unparalleled opportunity in terms of conservation of resources and energy performance improvement. Increasing amounts of bio-based insulation materials are being utilised in buildings. The aim of this thesis was to develop a bio-based low carbon construction composite based on local miscanthus shiv from the Taunton area (Somerset, UK) and investigate its performance properties as an innovative insulation material. The materials development approach included a proposal of a mix design methodology,
a selection of mineral binders and an experimental investigation of the chemical, mineralogical and microstructural interactions between the binders and miscanthus bio-aggregates. The performance characterisation included strength development, thermal and moisture transfer properties, and acoustic optimisation. The investigated mineral binders consisted of a blend of 75% hydrated lime and 15% natural hydraulic lime, whilst the remaining 10% was either Portland cement or pozzolanic additions (ground granulated blast-furnace slag and fly ash). Mix designs were produced using a binder to aggregate ratio of 1.5-2.0 and raw miscanthus shiv and testing samples were cured in indoor air conditions for 28 to 90 days. Samples exhibited external shell hardening and inner core softening (‘powdering’) for some mixes. The chemical and mineralogical analysis showed low levels of carbonation and hydration in the range of 10.0-17.1% and 0.6-1.4%, respectively at 28 days of curing. In terms of strength development, formulated lime (FLA3.5) exhibited significantly higher
strength values compared to simple, binary, and ternary lime binders. This was due
to a coexistence of hydration and carbonation. These results were corroborated by
thermogravimetric and x-ray diffraction analysis results. Overall, binders incorporating mineral additions (slag, fly ash and cement), exhibited higher strength than hydrated lime and binary blends of hydrated lime and natural hydraulic lime. In the range of the investigated binder to aggregate ratio (b/a), the reduction of the b/a ratio from 2.0 to 1.5 has exhibited a rather low effect on strength development, particularly after 28 days. Overall, the developed miscanthus concrete has achieved compressive strength values of 207 kPa after 28 days and 482 kPa after 90 days, which are comparable to those of typical vegetal concretes with similar density values. The developed miscanthus lime composites exhibited dry thermal conductivity values of 70-77 mW.m-1.K-1. Therefore, miscanthus shiv can be effectively used in thermal envelopes of low carbon buildings. Miscanthus concrete composite recorded interesting moisture buffer values in the range of 2.06-2.25 g/m2.%RH, confirming its ability to contribute to modulating internal humidity levels in buildings. Acoustic transmission loss values in the range of 10-30 dB were recorded, suggesting beneficial contribution towards acoustic comfort in new builds and retrofits. The environmental assessment of miscanthus concrete has shown that miscanthus concrete can capture and store an average of 135 kgCO2/m3, suggesting a high potential of miscrete for use as a carbon sink in buildings. |
|
| dc.publisher |
University of Exeter |
|
| dc.publisher |
Engineering |
|
| dc.rights |
2024-09-26 |
|
| dc.rights |
The thesis still contains unpublished data. Embargo 26/9/24 |
|
| dc.rights |
http://www.rioxx.net/licenses/all-rights-reserved |
|
| dc.subject |
Low-carbon, sustainability, lime, bio-based, insulation, miscanthus, thermal conductivity, moisture transport, acoustic performance |
|
| dc.title |
Development of bio-based, low carbon and low cost building materials with improved thermal and acoustic properties |
|
| dc.type |
Thesis or dissertation |
|
| dc.type |
PhD in Engineering |
|
| dc.type |
Doctoral |
|
| dc.type |
Doctoral Thesis |
|