The Arborloo designs we have developed utilize a concrete mixture with natural, lightweight aggregates. The mixture contains crushed coconut shells and ground styrofoam, along with the traditional cement, sand, and water.
Our first design is a simple, circular slab. The slab measures 30 inches in diameter and will be an inch and a half thick. The center waste hole will be ~10 inches in diameter and will be controlled by using the bottom portion of a five gallon bucket. The circular slab will be cast using two thin steel strips that are held together by four screws. See BOM for mixture details and cost. The final slab should weigh roughly 45 pounds and support about 375 lbs.
Our second design is in the shape of a dome. The dome measures 30 inches in diameter and will be an inch and a quarter thick. The center waste hole will be ~10 inches in diameter and will be controlled by using the bottom portion of a five gallon bucket. The dome arborloo will be cast using a mold constructed out of Styrofoam sanded into a dome shape. Refer to the BOM and final mold designs for more information. There should be a plastic sheet between the mold and the wet concrete, to ensure that it releases from the mold easily. See BOM for mixture details and cost. The final slab should weigh roughly 31 pounds and supports over 400 lbs.
Although we were not able to perform adequate testing to justify them, handles were looked at for the slab to be used to carry it around. Further testing on anchoring the handles needs to be performed for safety reasons. Also coloring and stamping were looked at to improve ascetics of the designs. Each of these processes could be added to any slab without effecting the structural integrity of it. The reason they were not included in the final design were due to higher cost.