I want to fabricate nano silica for cement matrix purpose. please say me your idea, about size, shape and method of best synthesis. And what is your opinion about size distribution?
shape and in particular size (most important) of nano silica depends on the the goals to achieve. Generally speaking the finer the silica, the higher the reactivity and the pozzolanic index. In this way:
Nanosilica with a specific surface higher than 200 m2/kg is particularly indicated for high strength cementitious mixtures. For instance to produce RPC (Reactive Powder Concretes and Mortars: see some papers available on the subject in my research gate profile) very fine nano silica is necessary combined with a traditional silica fume (ss 25m2/kg). Remind, however, that the finer the nano silica the higher the water demand and/or the super plasticizer dosage. for this reasons it is not necessary in all situation yo use a very very fine nano silica.
In conclusion I suggest to produce different nanosilicas (in size):
- very fine (200 m2/kg) for special applications in high strength mixtures
- intermediate fineness for applications in prepacked mortars for repai and restoration of existing reinforced concrete structures
- normal fineness for production of durable and watertight concretes in very severe aggressive environment
regards
luigi coppola
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