What kind of defects can occur if concrete is poorly mixed?

Poorly mixed concrete can lead to some specific defects that significantly affect its performance and durability. When concrete is inadequately mixed, the components—the cement, aggregates, and water—may not achieve a uniform distribution. This can result in segregation, where heavier aggregates settle to the bottom while fines remain at the top. Such separation leads to uneven distribution of materials, compromising the concrete's integrity.

Bleeding is another defect that occurs when excess water rises to the surface of freshly poured concrete, creating a layer of water that can weaken the surface bond, making it susceptible to damage. This phenomenon is often exacerbated by poor mixing, which can result in an excess of water in the mix.

Additionally, inconsistencies in strength can arise from poorly mixed concrete because areas with insufficient cement or aggregates will not develop the same compressive strength as others. Different parts of the structure may perform variably, leading to potential failure or durability issues over time.

This combination of segregation, bleeding, and strength inconsistencies directly illustrates why option B is the correct choice, as these defects are closely linked to the quality of the mixing process.