P18485: Biochar Concrete Roofing Tile Manufacturing and Complete Roof System
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Test Results

Table of Contents

All Test Results

Concrete Test Samples

Below are the results comparing the different cure methods used. All of the samples in this graph didn't have any reinforcement in order to directly examine the effect of the cure. Based these results, it was determined that water curing is the best method.
Comparison of Curing Methods Used

Comparison of Curing Methods Used

Based on mixing observations and test results, we have decided to go with the Higher (40% Pumice, 30% Sand, 30% Cement) Ratio. While mixing the lower and higher ratio, it was observed that both mixtures contained too much water. Concrete has been shown to have an inverse relationship between water and strength. The reason for the equal ratio's performance was due to less water being used.

Below are the results comparing the different reinforcements used in the samples. All of these samples were water cured since it was determined to be the best cure method. These results show that the plastic string had an adverse affect on strength while the onion bag reinforcement maintained most of the strength of the concrete.

Comparison of Reinforcements Used (Water Cured Samples Only)

Comparison of Reinforcements Used (Water Cured Samples Only)

On most occasions, the onion bag and plastic string was able to sustain a load after initial failure. The plastic string was able to maintain a larger load after initial failure the onion bag. Based on this behavior, we determined that the best reinforcement method is plastic string placed randomly in one layer near the bottom of the tile.

Effects of Plastic String (Water Cured Samples Only)

Effects of Plastic String (Water Cured Samples Only)

All of the testing data can be found here.

Thermoforming Materials Test

In order to make the mold, we planned to thermoform plastic over a carved piece of foam with a protective coating on it. In order to determine the best combination of foam and coating, we thermoformed plastic over several test samples.
Thermoforming Test

Thermoforming Test

Test Samples

Test Samples

Test Results

Test Results

Based on the results of this test, the foam insulation board with epoxy was the most viable option. However, we would need to spend too much money on epoxy in order to coat the whole surface. We have instead decided to carve a negative out of the foam and use it to make a positive out of our leftover plaster, which we will then vacuum form over.

Strength Test

Description

The strength test was conducted in the Student Life Center by stacking weights onto the tile in 5 lb increments until failure. Two planks of wood were used to simulate the roof supports. The weights were stacked on top of a plexiglass sheet supported by a pair of shoes, in order to simulate the surface area and weight distribution of a person standing on the roof.

Test Results

Strength Testing With 250 lbs

Strength Testing With 250 lbs

The tile broke at 340 lbs, almost 100 over the ideal engineering requirement of 250 lbs.

Solar Heat Gain

Description

Both test roofs were placed outside in direct sunlight for 2 hours. The test took place on April 27th, 2018. The temperature on the inside surface of each roof was recorded every minute using an Onset HOBO External Temp/RH Logger. The sensors were switched from one roof to the other after one hour to ensure that they were providing accurate readings.

Test Results

Solar Heat Gain Test Results

Solar Heat Gain Test Results

 Solar Gain Temperature Difference

Solar Gain Temperature Difference

The point-by-point data can be found here.

Summary

The inside surface of the tile roof was on average 10 degrees Fahrenheit cooler than the metal roof. The metal roof also changed temperature more rapidly than the tile roof. The switching of the sensors from one roof to the other confirms that each sensor was showing an accurate reading. It should also be noted that at around the 82-85 minute mark and 100-101 minute mark the sensor became detached from the tile roof. This is the reason for the missing data points in the “Solar Gain Temperature Difference” graph.

Loudness Test

Description

The test was completed using a typical garden hose and a variable nozzle. The first setting used was the Shower setting. This setting is similar to light but steady rain. The second setting used was the Stream setting. This setting consisted of a single stream of water at a higher pressure than the Shower setting. We used this setting to simulate heavy rainfall.

Test Results

Loudness Test Results

Loudness Test Results

The point-by-point data can be found here.

Summary

Average Loudness

Average Loudness

Looking at the results in the table above, it can be show that the tile roof does a better job at soundproofing than the metal roof. Not only is the tile roof quieter in both simulated situations, the difference between the shower and the stream was roughly 2 decibels compared to a 14 decibel difference with the metal roof.

Waterproof Test

Description

The waterproof test was designed to test the water resistance of the tiles when assembled together on the roof. This test was conducted by assembling a test roof with 4 normal tiles and 2 top tiles. We sprayed the tiles for one minute with a hose nozzle on the "shower" setting to replicate rainfall. We wrapped the sides and bottom of the roof in plastic sheets, and lined the bottom with dry paper towels in order to observed any water that dripped through the roof.
Test Roofs for Waterproof Test

Test Roofs for Waterproof Test

Test Results

Waterproof Test Results

Waterproof Test Results

Based on our test results, the tile overlap method was successful in preventing water from entering the roof. We did observe drops of water that had landed on the paper towels; however, these drops were attributed to water coming in either from the sides of the roof or from water dripping onto the beam at the front of the roof.

Water Durability Test

Description

The water durability test was conducted in order to determine the ability of an individual tile to withstand constant water flow. This test was conducted by putting a tile in a sink and letting a stream of water run over it continuously for 4 hours. The water flow rate was about 67 mL/sec. After 4 hours, the tile was inspected for signs of water penetration.

Test Results

Water Durability Test Results

Water Durability Test Results

The inspection of the tile showed a darkened patch on the underside of the tile, near the area where the water flow was concentrated. However, it is difficult to draw conclusions from this test for the following reasons: 1. The tile was not fully cured, which could have led to a greater tendency for the tile to absorb water. It is possible that a fully cured tile would not show the same results. 2. While the tile does appear to absorb water, we were unable to observe an water actually dripping from the darkened spot. It is unclear whether the tile would actually let water pass through, or simply absorb the water to a certain capacity. 3. The tile surface was not perfectly smooth and had some bubbles, which may have contributed to the tile absorbing water. It is possible that removing all bubbles from the top surface would prevent this from happening.

Wind Lift Force Test

Description

The wind lift force test was designed to determine whether hurricane winds could detach a tile from the roof. Based on ASTM standards, a class 1 hurricane has wind speeds of 74 mph, while a class 2 hurricane has wind speeds of up to 110 mph. Using the formula for force of a fluid on a flat stationary plate
Wind Force Equation

Wind Force Equation

We calculated that the maximum force that could be imparted by these winds on a tile is 36 lbf for class 1, and 81 lbf for class 2. Therefore, if the tile could resist being pulled off the roof at over 81 pounds of force, it would meet the ideal criteria. The test was conducted by attaching a tile to the roof, attaching a clamp to the tile, and pulling upwards on the clamp with a hanging scale until the tile was removed. The hanging scale recorded the maximum load. This test was done with only one wire attached to the roof, with the clamp attached near this point, and the max load to remove it was doubled to estimate the force required to remove both wires.

Test Results

The results of this test showed it took 75 lbf to remove one wire, meaning it would take 150 lbf to remove the tile entirely. This is well above the ideal criteria of 81 lbf.