Paper

Agricultural Waste Fiber in 'An Economy That is Restorative and Regenerative by Design'

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Abstract

This project investigates the use of grass fibers and how they can be used in “an economy that is restorative and regenerative by design”, this is the definition the Ellen MacArthur foundation uses to define a Circular Economy. From an initial investigation by a graphic designer into the use of grass fibers for paper making a collaborative research initiative was established to analyze the properties of several grasses to better understand their structural strength and hydrophobic characteristics. Working with undergraduate research assistance from material science and fine and applied arts several perennial grasses and agricultural “waste” fibers were systematically studied. Initially meadow grasses were analyzed for their potential as an annual source of fiber for paper production as opposed to the clear-cut felling of trees for pulp. Following a couple of seasons of hands-on experimentation, the research became a more rigorous form of enquiry in which 10 plant types were studied down to the scale of a micron. In the process several preliminary findings related to tensile strength and hydrophobicity were discovered. In 2017 another form of inquiry was initiated to see if various grass fibers could be used in three dimensional constructs. This research focused on three grasses for the following reasons: corn stover, due to its ubiquity across the region in which the research was being conducted, miscanthus because it’s a high yielding perennial rhizomic plant with a high lignin content, and the hurd from hemp because it has been used in wall construction since antiquity and provides a good base case for comparative analysis. In 2018, with the assistance of an undergraduate student and assistant professor in the department of Material Science and Engineering, the thermal resistance properties of these three different grasses were analyzed using the flat plate method. The results were very similar for the three grasses tested, with both miscanthus and corn stover slightly outperforming hemp with an average conductivity of 0.1 W/mK or an R value of 1.3 per inch. In the spring of 2019, a three-foot tall mockup wall was constructed in the context of a graduate seminar class. The grass fibers which were milled to a somewhat uniform dimension, were mixed with hydrated and hydraulic lime, and tamped down into wooden formwork. Over time the lime binder hardens preventing the fiber from being affected by mold or insect attack. In the summer of 2019, a Master of Architecture Research Assistant was appointed to develop construction drawings for permit approval to build two 14 ft. tall experimental walls. Over the following three months, with the help of two more research assistance, the two walls were constructed. Each wall contains three different mixes: hempcrete, a corn stover-lime mix, and a miscanthus-lime mix. The current phase of the research involves the analysis of the walls using thermal humidity sensors and thermal imaging. Research is also underway to replace the lime that is in the mix with a geopolymer material with better thermal and structural properties as well as a lower carbon footprint.

Keywords: Thermal Perfomance, Miscanthus, Hemp, Circular Economy

How to Cite:

Taylor, M. S. & Smith, K., (2023) “Agricultural Waste Fiber in 'An Economy That is Restorative and Regenerative by Design'”, Building Technology Educators’ Society 2023(1), 136-146. doi: https://doi.org/10.7275/btes.1946