Civil Engineering Reference
In-Depth Information
Specific effects of SCMs
The decrease of pH caused by the introduction of SCMs causes a reduction
in the amount of chlorides necessary to destroy the passive layer and
initiate corrosion, but this negative effect is counterbalanced by the chloride
binding of certain SCMs (GGBS, fly ash, metakaolin), and by the decrease
of chloride diffusion due to the segmentation of the porosity (GGBS, fly
ash, metakaolin, silica fume). The overall result is generally a significant
decrease of chloride penetration, as shown on Fig. 8.12. All results show
lower coefficients of diffusion, and the efficiency depends on the reactivity
of the pozzolan. This could results in longer service life of structures, as
reported by McNally and Sheils (2012) in their probabilistic service life
prediction of concrete with GGBS.
100
90
80
70
60
50
40
30
20
10
0
GGBS
Dhir et al. (1996)
Ryou and Ann (2008)
Thomas et al. (2008b)
Kessler et al. (2008)
Zeljkovic (2009)
Elahi et al. (2010)
Gruyaert et al. (2010)
0
10 20 30 40 50 60 70 80 90 100
GGBS content (%)
100
90
80
70
60
50
40
30
20
10
0
Fly ash
Byfors (1987)
Dhir and Byars (1993b)
Ryou and Ann (2008)
Elahi et al. (2010)
Baroghel-Bouny et al. (2011)
0
10 20 30 40 50 60 70 80 90 100
Fly ash content (%)
8.12
Effect of mineral admixture content on the coefficient of chloride
diffusion, relative to the reference. Data from Gautefall (1986), Byfors
(1987), Gautefall and Havdahl (1989), Luping and Nilsson (1992), Dhir
and Byars (1993b), Dhir et al. (1996), Cabrera and Nwaubani (1998),
Boddy et al. (2001), Oliveira et al. (2005), Kessler et al. (2008), Ryou
and Ann (2008), Thomas et al. (2008b), Zeljkovic (2009), Elahi et
al. (2010), Gruyaert et al. (2010), Baroghel-Bouny et al. (2011), San
Nicolas (2011).
