The durability, or service life, of a building element is a function of the material and the environment. Precast prestressed concrete will provide reliable, long-term performance in extremely harsh conditions that can destroy lesser materials. Precast is resistant to deterioration from weather extremes, chemical attack, fire, accidental damage and the determined efforts of vandals.
The production of precast concrete elements under controlled plant conditions allows for accurate control of the results; e.g. tolerances and concrete quality. The concrete used in precast components is usually denser, stronger and is almost always of better quality than concrete cast at the jobsite.
The most common deterioration of concrete structures is the corrosion of the steel reinforcement. Protection of reinforcing steel from corrosion can be obtained by proper embedment in concrete. A protective iron oxide film forms on the bar as a result of the high alkalinity of the cement paste. This protection can be lost by leaching and carbonization. Concrete with sufficiently low permeability and adequate cover will protect the reinforcement. Hairline and structural cracking may allow oxygen and moisture to reach the reinforcement, providing conditions where rusting of the steel and staining of the concrete can occur. In precast production, the concrete cover to the reinforcement ratio is better controlled. Precast concrete is stronger, manufactured to better tolerances and prestressed (with its lower usage of steel) to provide better durability in harsh environments.