Initial tests were done by the previous project lead, Josephine Muss, so the exact procedure is unknown due to a lack of exact procedural documentation. To the best of my knowledge, these samples were created using a pipe and c-clamp setup, which I currently don't have access to but will add to these notes when I do get access. These were then heated with insulation at 140 degrees for Sample 1 and at a temperature above 140 degrees (exact value unknown) for Sample 2.
Sample 1 is significantly less brittle than Sample 2, and has stronger resistance to normal stresses than Sample 2, which shows buckling and sounds like it's breaking, similar to the response to shear stresses. Both are weaker torsionally, but I wasn't able to fully twist sample one with normal levels of force, while sample 2 twisted with ease. While both had some pieces falling off, Sample 2 had significantly more flaking off.
As we advance with testing, we aim to develop a solid material with only pressure and heat without the need for a chemical binder, as previously used in StakBlock testing. When access to the lab is regained, we will be conducting a battery of tests with varying pressure and temperatures, in the order in which they occur. We will also be constructing a new device to simulate a square piece rather than a cylindrical one, as is currently being used. This means that we will no longer have to consider torsional stress, but still consider everyday and shear stresses along with any non-planar stresses. We will be using piece density currently as our benchmark until we gain access to more sophisticated measuring devices, which we hope to access after we meet with Bing Qu, Head of the CENVE department.
Some general steps forward for this project (in my mind) are as follows.
Reliably produce a product with a pressure/temperature ratio with the desired density.
Design and/or produce the desired shape of the product, making any changes to the previous step if needed
Materials testing of said product, some possible tests are...
3.1: Optical | 3.2: Durability | 3.3: Environmental | 3.4: Mechanical | 3.5: Flammability | 3.6: Permeability
The possible use of any coatings and what those would be
Over the next two days, we have four meetings: one with Dr Bing Qu, Dean of the CENVE department, to discuss the project in the morning, and one in the afternoon to inspect the CENVE shop; one with Dr Philip Costanzo, an adhesive chemist, and one with Doug Brewster, a CSM Equipment Technician. The takeaways from these meetings will be detailed below
In the meeting with Dr Bing Qu, we discussed several aspects of the project. Bing was already familiar with the original project started by Ben Korman over a decade ago, as well as his research into a similar project using soil material instead of agricultural waste products. We identified together that our current goal is to achieve a temperature-pressure-density mapping for the material, which was a necessary first step before any testing is done. From there, we will create small-scale bricks theoretically using department machinery, which we will tour later. The tests conducted on this cannot be directly related to our final large-scale product, but we can extrapolate features of them. We also emphasized that we need to figure out its strengths, such as ease of use, replacement, and structural features that make it more competitive than other building materials. Bing also brought up that we may use this as a filler material that is around a timber or steel frame rather than the entire structure itself. There is great merit to this idea, especially considering previous projects have used rebar and grout as a structural support, implying that these blocks are not used by themselves.
In the meeting with Dr. Constanzo, we briefly reviewed the next steps for the project and his involvement. Overall, the steps we currently see needing to involve chemistry are with a water-resistant outer polymer layer. But things may change as we evaluate the next steps we need to take, especially with the involvement of various agricultural waste products. We also identified that we need to have a contact within the CAFES department to procure some waste products to begin testing. I will be reaching out to someone in the department soon to gauge interest.
The second meeting with Bing covered the different Civil Engineering lab equipment. I've attached photos of these below. These will probably be used down the line for larger structural testing.
Press 1 (CE Shop)
Press 2 (Bonderson Shop)
Press 3 (CE Shop)
Press 3 Information (CE Shop)
In this meeting with Doug, we discussed and designed the prototype for our device to be used in the press seen below.
After returning from remote, we performed the first test; all test results can be seen within the Important Files section of this website. Overall, the first trial run went well, but we observed that the pressure gauge may be broken. Setup can be shown below, along with the first sample gathered.
Sample 1
Settup Heating Up Sample
Settup Fully Heated Sample
Moisture Given Off By Mulch
Sample 10 is the first straw sample that had meticulously detailed notes. To the left is the graph of the material over the experiment. These are calculated values that are modified based on the final results of the sample that comes out at the end. The purple line represents the temperature of the sample during the experiment. The heater is turned on at 21 minutes and turned off at ~103 minutes. Red represents the density of the subject, calculated based on the amount of the plunger visible through the machine. Pressure is then calculated based on the weight on the lever and the number of pumps done over time. All numbers in detail can be seen in the Important Files tab.
This is Sample 10, the ends crept around the wooden plunger so we had to shave parts of it off
Experimental Settup