Influence of nano-silica on the hydration characteristics of air-cooled slag-blended cement.
The philosophy of silica materials addition or pozzolanic materials is to react calcium hydroxide liberated from cement hydration with silicon to produce cent gel . Siliceous Cement Gel which is produced is regarded as a secondary gel as well as with produced from cement hydration .The gel resulting is reflected positively on strength of concrete .Nano silica fume is regarded very active pozzolanic material to react with silicon in slag blended cement and with that calcium hydroxide .
In addition to the effect mentioned by Jaber, in which the silica form more C-S-H, there is the packing effect of the nano particles, which densifies the microstructure increasing strength and reducing permeability. There is also an effect of the nano particles, in which these act as centers for heterogeneous nucleation, which favors the precipitation of CSH from the cement, so it can accelerate the rate of hydration of the cement fraction, which will produce more CH, which will react with the slag and nano particles.
Nano-silica (NS) behaves not only as filler and nucleating agent to promote the hydration of cement phases and improve the microstructure of cement paste, but also as Pozzolanic material (PZM).
I also agree with that, NS can form more C-S-H, there is the packing effect of the nano particles, which densifies the microstructure increasing strength and reducing permeability. There is also an effect of the nano particles, in which these act as centers for heterogeneous nucleation, which favors the precipitation of CSH from the cement, so it can accelerate the rate of hydration of the cement fraction, which will produce more CH, which will react with the slag and nano particles.
NS acts not only as a filler to improve the microstructure of
cement paste, but also as an activator to promote pozzolanic reaction. Both the nucleation and pozzolanic effects of NS lead to more accumulation and precipitation of hydration products in the open pore volume, leading to the formation of uniform, dense and compact microstructure. Consequently the bulk density and compressive strength increase with NS%.
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