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Nano-silica's Effect on compressive strength

wallpapers News 2021-07-16
Cementing faces a challenge at low temperatures, where there is slower heat of hydration reaction due to which cement takes more time to set resulting in a reduction in the compressive strength of cement. Upon investigating the relationship between the compressive strength of cement slurry and temperature, it was found that at low temperatures, the compressive strength of the slurry is less. It becomes necessary to ensure cement integrity and compressive strength of cement at low temperatures. Adding nano-silica to the cement slurry can effectively increase the compressive strength of cement slurry at low temperatures. An economic feasibility study should be carried out before incorporating nano-silica in the cement slurry.
 
Nano-silica is capable of increasing the density of concrete and improves the mechanical properties of concrete. It promotes pozzolanic reaction resulting in enhancement of durability and mechanical properties of cement. It has been observed that with increasing weight percent of nano-silica, the compressive strength of the cement increases. However, if the proportion of nano-silica in the cement slurry exceeds some certain amount there can be a decrease in the compressive strength of cement.
 
When cement slurries with increasing weight percent of nano-silica were studied, a trend of increasing compressive strength was observed. When comparison was made between slurry containing 0% nano-silica and slurry containing 1% nano-silica, a 100% increase in compressive strength was reported. Slurry with 1% nano-silica demonstrated maximum compressive strength. It was observed that the compressive strength of a slurry containing 1.5% nano-silica was 7% lower as compared to a slurry containing 1% nano-silica. The addition of nano-silica improves the bond between cement matrix and aggregates. This helps in producing concrete with high compressive strength.
 
As compared to fly ash, ordinary portland cement (OPC), and silica fume, nano-silica has high compressive strength. The compressive strength of NS is 9.5% of that of OPC. This is enough evidence that upon the addition of nano-silica in the cement slurry, the compressive strength of cement slurry can drastically increase. Upon incorporation of nano-silica in cement, with an increase in the compressive strength of cement, an increase in viscosity is also reported.


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