| 1. |
- Lövgren, Ingemar, 1972, et al.
(författare)
-
Predicting chloride induced depassiviation and minimum concrete cover with different binders
- 2016
-
Ingår i: Materials, Systems and Structures in Civil Engineering 2016 - Segment on Service Life. 1. - 9782351581704 ; 1, s. 155-164
-
Konferensbidrag (refereegranskat)abstract
- Corrosion of steel reinforcement represents the major cause affecting durability of reinforced concrete structures in road and marine environments. To assure durability, standards attempt to provide specifications for long-term performance by simple deemed-to-satisfy rules for approximate environmental classification. This paper presents results from a study of modelling of chloride ingress in concrete with fly ash and ground granulated blast-furnace slag. Chloride threshold values for corrosion initiation are discussed. A physical model, ClinConc, was employed to calculate the chloride ingress profiles after exposure under marine (submerged) and road environments for 100 years. The model was validated using field data after exposure in the Swedish seawater for about 20 years. The results show that the addition of mineral additions in general increases the resistance of concrete to chloride ingress and allows smaller concrete cover thicknesses. However, one critical parameter is the chloride threshold value. In consideration of both the chloride resistance and the alkalinity, which influence the critical chloride threshold value, the concrete with mineral additions still reveals sufficient margin to allow a significantly lower chloride threshold for initiation of corrosion of reinforcement steel in concrete.
|
|
| 2. |
- Lövgren, Ingemar, 1972, et al.
(författare)
-
The influence of carbonation and age on salt frost scaling of concrete with mineral additions
- 2016
-
Ingår i: Materials, Systems and Structures in Civil Engineering 2016 - Segment on Frost Action in Concrete. - 9782351581827 ; , s. 91-100
-
Konferensbidrag (refereegranskat)abstract
- Resistance to salt frost scaling is tested by accelerated methods such as CEN/TS 12390-9 which originally were developed for Portland cement concrete. However, it has been shown that ageing and coupled deterioration mechanisms, like carbonation or leaching, alter the frost resistance. An example is concrete with high amount of slag where the frost resistance is reduced when the concrete is carbonated. Hence, modifications to the test methods have been proposed to take these effects into account and often an accelerated carbonation at an early age have been used. Though, it has been found that the accelerated tests show a much more negative effect than what is experienced in field conditions. This paper presents results from a laboratory study of concrete with mineral additions at different dosages and water/binder ratios which have been exposed to accelerated carbonation at 1% CO2-concentration at different ages. The results show that exposing the specimens to accelerated carbonation at a young age will result in an increased scaling but that the carbonation depths corresponds to 10 year natural exposure. By increasing the age before the accelerated carbonation exposure the scaling is significantly reduced and the salt frost scaling resistance seems to correlate better with field observations.
|
|
