Design and development of cellulose based composites for the built environment

Veigas, Melvin
Major Professor
Ulrike Passe
Behrouz Shafei
Committee Member
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Cellulose is a versatile material with numerous contemporary applications in textiles, food, and biomaterials. Contemporary research is focused on modifying the structural and thermal properties of cellulose to create novel composites with cellulose nano-crystals, lignocellulosic pulp, and foamed cellulose to name a few. Significant advances have been made in improving the properties of cellulose. Adding aligned cellulose nano-fibers to concrete to improve its mechanical properties or combining with polymers for better durability can lead to new applications specifically in design and construction. These new forms of cellulose through optimization and combination with other materials provide opportunities for reducing material usage, as the life-cycle cost involved in the transformation of traditional materials such as brick, concrete, and steel in construction is significant. Therefore, this thesis reviewed cellulose research pertinent to the field of building construction and explored three cellulose based applications at two different scales.

The three investigations explored utilizing cellulose, in two forms, as an alternative to non-renewable materials that constitute the standardized wall assembly. Focusing on a widely available, renewable, and bio-degradable material such as cellulose would provide an alternative to the energy intensive materials that make up the standardized wall assembly. Therefore, the primary goals were:

1. Reducing the percentage of non-renewable materials utilized in the contemporary wall assembly.

2. Utilizing a widely available, biodegradable, and renewable material like cellulose as an alternative to traditional building materials.

3. Transforming cellulose, manifesting as various fibers, into a structural or thermal component based on location, availability, and programmatic requirements.

For the first study, the mobile diagnostics lab was utilized to generate Data from custom concrete panels inserted into the removable wall assembly creating a baseline to compare future cellulose concrete panels. The fiber composite study primarily optimized fiber proportion for effective mechanical properties. Therefore, additional work needs to be carried out into fiber and mix proportion optimization to create a thermally efficient composite panel.

For the second investigation, cellulose based thin shell structures were cast as a framework for future applications utilizing cellulose available in various forms around the world (Table 5 1). The shells were envisioned as enclosures for community gathering spaces in rural regions. Additionally, they could serve as a blueprint for crafting spaces in regions facing humanitarian crises and shortage of traditional building materials such as lumber, glass, steel, and brick.

The third study investigated the interfacial bond between the fiber and cement matrix in concrete by coating the fiber surface in polyester resin and shellac prior to dispersion in the composite mix. The coated sisal fiber embedded composites exhibited improved toughness, ductility, and flexural capacity, compared with unreinforced ECC composites.