What are the consequences of inadequate compaction in concrete?

Inadequate compaction in concrete leads to increased formation of voids within the finished product. Proper compaction is essential in ensuring that the concrete mix is dense and free of air pockets or voids. When concrete is not compacted sufficiently, small air bubbles and larger voids can remain trapped within the mass, creating weak spots in the material.

These voids can severely compromise the concrete's performance by reducing its strength and durability. Voids can lead to issues such as increased permeability, which can allow water and other detrimental substances to infiltrate the concrete. This can result in corrosion of embedded reinforcement steel and diminished structural integrity over time.

The other options are incorrect in the context of inadequate compaction. Improved durability and strength, enhanced appearance of the surface, and decreased cost of materials would not result from insufficient compaction. Instead, they are outcomes associated with well-compacted concrete that effectively maximizes strength, aesthetic quality, and overall durability.