3.1 Materials
3.1.1 Dry Undensified Microsilica
This form of silica was 猀old ìas producedî from the ferrosilicon or silicon metal bag
house, generally in bags. The undensified microsilica might be slightly agglomerated
and densified due to pneumatic handling, de-aeration in packaging, in addition to
pressure and vibration caused during transportation.
3.1.2 Dry Densified Microsilica
The air densified silica fume is processed by air injection into the bottom of the steel
storage silos creating turbulence and collision between silica fume particles. The
pressure-densified material is obtained by passing the uncompacted fume through a
device that compresses the individual particles together.
Both compacted forms are easily reversed and separated back to individual particles by
the shearing forces generated in concrete mixing. Composition of microsilica is given in
Table 1.
3.1.3 Cement
Ordinary Portland Cement (OPC), (ASTM Type-1) and Sulfate Resistant Cement (SRC)
(ASTM Type-V) were used in all concrete mixtures. Their chemical compositions are
given in Table 1.