What is the result of vibration of the concrete material?

• A. Increased permeability
• B. Faster curing time
• C. Increased compression strength
• D. Reduction of voids

Answer: (D)

Vibration of fresh concrete compacts the mix, helping air to escape and the cement paste to fill the spaces around the aggregates. This consolidation directly reduces the number and size of voids in the concrete. With fewer voids, the material becomes denser, which also tends to lower permeability. While vibration can contribute to higher strength, the most direct and defining outcome described here is the reduction of voids.