Prestressed Precast Concrete
Types and Durability
| Description
Structural Precast Prestressed Concrete |
Expected Lifespan
( Years ) |
Adjustment Factors |
| Internal | ||
| Precast prestressed columns/beams complying with BS 8110: Parts land 2, with cover to steel complying with Table 3.3 and specified to match the appropriate exposure category selected from Table 3.2. Minimum nominal cover to all reinforcement of 20mm. Minimum cement content 275kg/m³. | 35+ | 1st stage adjustment factor:
In industrial areas (heavy polluted): -15% years In urban areas: -10% years In suburban areas: -0% years 2nd stage adjustment factor: Structural members subjected to ‘very severe’ exposure conditions to Table 3.2 of BS 8110:Part 1, without additional surface protection:-30% years. Within 20m from express way: -20% years Within 20m from major arterial road: -10% years Within 20m from light traffic road: – 5% years Within 20m from sea water/ prone to salt spray: -15% Test certificate from approved local testing authority : +15% years |
| Unclassified, ie beams/columns not complying with BS 8110: Parts 1 and 2. | < 35+ |
Combination of adjustment factors (1st stage and 2nd stage) should be added to obtain the durability values
Refer to durability calculator.
Notes: Overloading of beams must be avoided. The most common causes of overloading are point-loading or poor handling during storage and installation, or due to changes in specification (e.g. from a floating deck to a screed, or from lightweight partitions to masonry partitions). Such changes must be advised to the beam manufacturer or the structural calculations rechecked for adequacy.