# Thermal Expansion in Concrete Bridges

## How does temperature affect the gap between concrete slabs in a bridge?

On a 115°F day, the slabs just touch. What is the gap between the slabs when the temperature is 0°F?

## Answer:

The gap between the concrete slabs when the temperature is 0°F can be calculated using the concept of thermal expansion.

Concrete slabs in bridges expand when heated and contract when cooled due to thermal expansion and contraction. This phenomenon is a result of the material properties of concrete.

The change in the length of a bridge due to temperature fluctuations can be calculated using the formula for linear thermal expansion, which is ΔL = αLΔT. In this case, the coefficient of linear expansion for concrete is approximately 10 x 10^-6 per °C.

By calculating the change in length when the temperature drops from 115°F to 0°F for concrete slabs that are 275 cm long, we find that the gap between the slabs will be approximately -0.835 cm at 0°F. The negative sign indicates that the slabs will contract, creating a gap between them.

Therefore, temperature plays a crucial role in determining the gap between concrete slabs in a bridge, showcasing the importance of considering thermal expansion and contraction in bridge design and construction.