Concrete Encased Steel
Types and Durability
|
Description Concrete Encased Steel |
Expected Lifespan ( Years ) |
Adjustment Factors
|
|
Internal
|
||
| Hot rolled steel encased in insitu concrete to BS 8110: Parts 1 and 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 Test certificate from approved local testing authority : +15% years |
| Structural hollow section with the concrete filling to BS 8110: Parts 1 and 2. |
35+
|
|
| Unclassified, ie concrete encased steel beams, concrete encasement 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.
Key durability issues
Thickness of concrete encasement, curing/compaction of cement mix, cement content suitable for exposure, protection against sulphates, chlorides, acids (e.g. fumes, chemical spills), detailing.