Monday, June 20, 2011

NCSU Engineering Camp 2011: Civil Engineering part 4

Day 4: Water Filters
The first half of Day 4 consisted of designing an water filter in an clear plastic cylinder out of coal particles, sand and gravel. Our objective, of course would be produce the cleanest water, but the quality of water isn't the only factor; time and cost are factors. Water quality accounts for roughly 70 percent of the score; the other two components are 15 percent each. Because each team starts out with one bag of each ingredient type, the cost isn't going to differ too much from group to group. The reason why each group might have similar amounts of ingredients is largely because to achieve favorable speed, there must be a favorable pressure.

Because p = ρgh where p and g are constants, a greater height is required to attain a greater pressure. Therefore, people did not want a filter that would fill all the way to the top of the cylinder because there isn't enough pressure, hence velocity to move the water through the filter. Our instructor mentioned a group in the 2010 Engineering Camp which filled the filter all the way to the top and the entire filter became clogged instantly; no water was able to move through. To stay competitive, everybody kept the filter to approximately half of the cylinder's depth to allow sufficient pressure to allow water to pass through the water filter.

Day 4: Our Design
Our group's design was alternating with layers of gravel in between layers of sand and coal. Then to top it off, we added a layer of gravel at the top so that the initial flow would be quick and sustained. However, we went into problem areas when we hit the sand, to which we put sightly too much of it near the bottom of the cylinder. Because there isn't as much water near the bottom, the height effect of pressure on water has decrease tremendously, slowing down our rate of flow significantly. However, our design worked perfectly find for the first two minutes, producing a viable stream of water out from the end of the cylinder. However, after the two minutes has passed, our filter seemed to be clogged very badly. Our group believed that the excessive amount of sand and coal particles could be sources of the clog. Despite the alternating layers of sand and gravel that we placed to allow better transition from one layer to another, it ultimately proved to have little to no effect on the transition; it merely decreased the maximum pressure level that we could have. At the end, it took our filter nearly 30 minutes just to filter a liter of water, which despite our cleanness ultimately dragged us all the way down to last place in the water filter competition.

Day 4: Testing our concrete cylinder
On the last day of camp, the day of judgement has arrived for our concrete cylinders. The concrete cylinders that we made on the first full day of camp has been siting in the curing chamber for virtually four days. In that period, we allowed our concrete mixture to undergo the necessary chemical reaction necessary for bonding between the sand and gravel aggregates along with water. To test our concrete cylinder, we placed under a heavy robotic arm that transfers compressive force to a circular plate downwards. This force is then transferred down to the concrete cylinder. The cylinder test is a measure of how much pounds of pressure that an concrete cylinder could sustain when it has failed (fractured). This unit is measured in kips which is equivalent to 1000 pounds of force. Normally, a fully cured concrete could sustain roughly 90 kips or 90,000 lbs of pressure; however a very strong concrete mixture that have only be cured for three days could have a possible 50 kips of strength. Amazing to us, our concrete cylinders did amazingly well; our second cylinder was able to sustain 51 kips upon it when it failed. We could look back to this success because we were able to slightly neutralize the mixture so that it wouldn't be so aqueous. But we added extra gravel and the slight aqueous mixture allowed the cement to have enough liquid to commence the chemical reaction necessary for a strong concrete. Also, the gravel gave it added strength. Our extra sand filled all the air holes and provided a form of binding agent. With 51.6 kips for our first cylinder along with 51.0 kips for our second cylinders, we won the strength competition. However, we had the most expensive concrete mixture which adversely affected our score to the point we didn't get the best overall score in the concrete engineering competition.

Day 4: our opponents and how they matched up
We had a competitor whose cylinder achieved a 51.09 average overall who had the final best overall score of the concrete engineering competition. Of course, their concrete strength is very close to ours, but they spent the least money on making the concrete. How? Well, they had the same proportion of sand and gravel and water components. We spent more money making a greater quantity of the same mixture. This added to our cost; we couldn't use the extra concrete mixture. In practice, if our aim was to make only three concrete cylinders, then our mixture would have been extremely inefficient; thank goodness we didn't get penalized for having excessive concrete mixture!

Overview: Day 4 and Engineering Camp
This camp has been an exciting opportunity for me to expand my understanding of architecture from an civil engineer's perspective; It has taught me many skills that I believed would have helped me in my journey with architecture; for example the camp has taught me the skill of micro management; which would help me in the future when I'm designing a building. Every component is worth cutting costs on; it can lead to an efficient, hence green building. Civil Engineers try to find out the most creative way to solve problems; architects try to find the most creative way to express their ideas, but as I learned architects could do the same; it's just that architects provide the framework for civil engineers to build upon. This camp has helped me form a concrete connection between Architecture and Civil Engineers. Architects are not alone; Civil Engineers and Construction workers alike all have to be able to understand each other and work together to provide for a better future.

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