Document Type

Restricted Campus Only

Publication Date

4-23-2024

Abstract

The “Plastic Wall-E” team has worked diligently to design a processing and construction method that allows plastic waste to be incorporated into a structural wall with a minimal environmental impact. The project sponsors of the Samadhi Yoga retreat recognized a critical issue with the accumulation of plastic waste in remote locations requiring transportation to recycling facilities and in countries with major plastic pollution problems where there is typically a lack of proper recycling facilities. The project aims to address the plastic waste crisis by maximizing the density of plastic waste that can be contained in a masonry wall while minimizing the toxic emissions from melting plastic. Additionally, the team’s final plastic process design must allow for easy machine implementation.

The team's final design consisted of two subsystems for testing: the plastic waste process for machine incorporation and a masonry wall configuration that allows for structural rebar and a significant storage of plastic waste. The final design for plastic processing was a plastic “cube” fabricated by funneling and compressing shredded plastic waste into an open water bottle that is then quickly heat-sealed and compressed to contain the loose plastic waste. This design addresses the project objectives by condensing plastic waste into a small sealed container that can be used as filler in a common masonry wall configuration while minimizing the quantity of plastic being melted.

The other subsystem focused on the configuration of the masonry wall that acts as a containment vessel for the sequestering of plastic waste while also being able to incorporate metal rebar for structural construction purposes. Based on ASTM codes for metal rebar spacing, the team will have a maximum spacing of 48 inches to allow as many empty spaces created in the wall [‘void columns’] where the plastic cubes can be contained [1].

To evaluate the effectiveness of the team’s final design, the team conducted two tests on the plastic processing subsystem to quantify the plastic density and emissions from cube production, and a test for the masonry wall subsystem by conducting simulated force testing.

The plastic density test quantified the amount of plastic waste that could be contained in each cube based on plastic mass. The average plastic mass for each cube was 87.93 grams or approximately 7-8 water bottles condensed into a 6-inch tall cube. Based on the dimensions of the cube and the estimated volume of the void column, approximately 30 cubes can fit when horizontally stacked into a void column. This translates to approximately 2.6 kg of plastic for every void column or around 10.5 kg of plastic waste for every 3.5-foot x 4-foot wall segment. This far exceeds the original project requirement which required 0.5 kg of plastic waste to be encapsulated in each brick, which would have a total wall plastic mass of approximately 5 kg.

The plastic emissions test evaluated the total volatile organic compounds (TVOCs) and CO2 gas emissions during the heat compression process. Based on safety levels for air quality index (AQI), the team required emissions for TVOCs and CO2 to be below 0.2 mg/m3 and 800 ppm, respectively for an excellent classification or a good AQI classification emissions below 0.6 mg/m3 and 1000 ppm [4]. TVOCs and CO2 measurements were made with an indoor air quality detector during the production of 6 cubes and found a peak CO2 concentration to be ~801 ppm, while the TVOC had a maximum concentration of 0.223 mg/m3. These production emissions would meet an acceptable classification The masonry wall test evaluated the structural integrity of the team’s wall design and rebar spacing.

The team required the wall to be able to withstand a compressive stress of 3 ksi and a shear stress of 0.3 ksi. The wall was tested via two CAD models made in Autodesk Inventor, a model of the full wall to test tipping and a smaller-scale model to test mortar slipping. Considering both models, the wall experienced a maximum Von Mises stress of 1.0 x 10-3 ksi meeting the compressive and shear stress requirements outlined by the project requirements.

Comments

Advisor: Dr. Enright

Download

Share

COinS