1. Are asphalt or concrete roads smoother?
2. This experiment is to determine by simple measurement if hot-mix asphalt or concrete materials make smoother roads.
3. Topic was chosen after noticing difference between hot-mix asphalt and concrete on Interstate highways.
4. My hypothesis is that hot-mix asphalt makes smoother roads.

1. Measure smoothness of three 100 linear feet asphalt road samples by measuring amount of liquid displaced from open container being carried over sample in wagon.
2. Measure smoothness of three 100 linear feet concrete road samples by measuring amount of liquid displaced from open container being carried over sample in wagon.

1. A lesser amount of liquid was displaced on hot-mix asphalt roads than concrete roads.
2. A greater amount of liquid was displaced on concrete roads than on hot-mix asphalt roads.

1. Asphalt roads are smoothest because of seamless construction and flexibility of binding agents.
2. Concrete roads are rougher because of seams between slabs and rigidity of binding agents.

• Some roads go thump, thump, thump and others are smooth and quiet. I wondered why that happens.
• My project was to study what products roads are made of and determine which product made the smoothest road. My study found that roads are mostly made of hot-mix asphalt or concrete. Roads in our state are made out of both products.
• Concrete roads are made of a mixture of portland cement, gravel, and sand. The mixture of these materials with water causes the product to harden and become concrete. Concrete pavements are called rigid pavements because they cannot be bent or compressed like asphalt. The cement in concrete roads is made of a powder that consists of calcium, silica, iron, and aluminum minerals.
• Asphalt roads are made of a mixture of liquid asphalt, sand, and crushed stone. The sand and stone are heated to a very high temperature and mixed with asphalt in a hot-mix asphalt plant. The mixture is trucked from the plant to the job site where it is laid with a machine and compacted with another machine. The asphalt is a thick liquid material that is brown to black in color and is made from petroleum. The liquid asphalt is the glue in hot-mix asphalt that holds the sand and stone together. Hot-mix asphalt is sometimes called flexible pavement since it flexes under the weight of traffic.

• To determine which product makes the smoothest road I performed an experiment on six different streets. All of the streets were in Charleston, WV. Three of the streets were concrete and three were asphalt. All of the tests were done on 100 feet samples.
• The experiment used a small red wagon, a cake pan, a glass bowl, a measuring cup, some water, and a note pad to keep the results. I placed the cake pan in the wagon and placed the glass bowl in the cake pan. I filled the bowl completely full of water and pulled the wagon exactly 100 feet and then measured in milliliters the amount of water that went from the bowl to the cake pan and wrote down the results. Then I compared the average amount of water lost on asphalt roads to the amount lost on concrete roads.
• Asphalt sample #1 lost 54 milliliters, # 2 lost 70 milliliters, and #3 lost 128 milliliters. The average water loss on asphalt was 84 milliliters.
• Concrete sample #1 lost 100 milliliters, #2 lost 115 milliliters, and #3 lost 135 milliliters. The average water loss on concrete was 117 milliliters.
• Based on the amount of water loss for the samples I tested, asphalt roads had less water loss than concrete roads. I divided the average amount of water lost on concrete roads by the average amount of water lost on asphalt roads to show that asphalt roads are 39% smoother than concrete roads, based on the results of my experiment.

• In conclusion, there are two reasons that I think asphalt roads are smoother than concrete roads. The first reason is that asphalt roads are seamless and concrete roads have seems between the slabs of concrete. The second reason the concrete surface is rough so that cars will not skid too easily.
• Now when I ride over West Virginia roads and hear the thump, thump, thump, I think I am on a concrete road. If the road is smooth and quiet, I think I am on an asphalt road.

(This was a class science fair project performed by Taylor Johnson. I have not edited it other than to put it into web format and add some color. Taylor's project was selected for presentation at the Kanawha County Science Fair at the Charleston Civic Center on March 14. Check it out!!!)