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. A lesser amount of liquid was displaced on hot-mix asphalt roads than concrete roads. A greater amount of liquid was displaced on concrete roads than on hot-mix asphalt roads. Asphalt roads are smoothest because of seamless construction and flexibility of binding agents. 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.