Examine how weathering occurs. Weathering is a form of erosion. In this type of erosion, the weather causes a substance to wear away quickly or gradually. Sometimes, weathering takes place when water pools and moves into the cracks of a hard substance, such as asphalt. When the water cools and forms ice, it increases in size and pushes the asphalt apart. The same process occurs in rock formations in nature. Weathering can also occur more slowly as water pushes through rock or asphalt and gradually wears it away.
Potholes form due to the weathering process. To create a road, asphalt is placed on top of a substrate. Gradually, the asphalt cracks slightly and water moves into the road. It slowly erodes the asphalt. When it gets very cold, water that has moved underneath or into the road surface can cause the asphalt to move up and down. Water also pools in cracks on top of the asphalt and turns to ice. When all of the water unfreezes, the asphalt has become weak and the pressure of vehicles gradually moves away the weakened asphalt, forming a hole.
To create a scientific experiment from your knowledge about weathering and pothole formation, examine whether potholes form more frequently when the asphalt is over a specific substrate. Look at examples of asphalt in your town and contact the public works department to determine the substrate that is underneath the asphalt. This might be soil, gravel or another substrate. During a very cold part of the winter when ice forms, compare the level of weathering of the two areas of asphalt. Measure the length and depth of any gaps in the asphalt. Measure the up and down movement of the asphalt. Determine whether there are differences in weathering between the asphalt on different substrates.
You can also do an experiment to determine whether the type of weathering influences the rate of asphalt erosion. Find someone who is repairing a sidewalk and ask for a small amount of asphalt. Get two large trays and place the asphalt inside the trays on a substrate, such as gravel. Let the asphalt dry. As it is drying, crack it slightly to provide an opportunity for erosion to occur. Measure the size of the crack in each piece of asphalt. Spray water repeatedly through one container. Place water in the other container and allow it to turn into ice. Remove the water from each container and measure the amount of weathering that occurred.