Civil Engineering Reference
In-Depth Information
spray tests with pH indicators show interesting results on steel surfaces after
ECE applications: titanium yellow, an indicator that shifts its colour from
yellow to red within a pH range of 12 to 13 (which should be achieved when
finishing ECE), changed its colour to red on rather blank reinforcement
surfaces after low impressed charges from about 50 Ah/m², stayed yellow
after applying 400 Ah/m² (see
Figure 8.5)
and became red also in visible pits
after applying 1,200 Ah/m².
8.6 Alkali-silica reaction (ASR)
Alkali reactive siliceous aggregates show an expansive reaction in the presence
of water and in a highly alkaline environment, forming cracks and alkali-
silica gel. Thus, if such aggregates have to be used, a cement with low Na
2
O
equivalent should be used (or cement replacement materials such as PFA and
potentials, surface resistivity readings and minimum concrete cover.
