Bond strength in cement and concrete refers to the adhesion quality between the cement paste and the aggregates or between different layers of concrete. The bond strength is crucial for the structural integrity and durability of concrete structures. It is influenced by several factors including the properties of the cement paste, the surface characteristics of the aggregates, the concrete mix design, and the curing conditions. Enhanced bond strength is achieved through the chemical hydration process of cement, where calcium silicate hydrate forms and mechanically interlocks with aggregates.