03. Effects on Air Entrainment of Fresh Concrete
The dosage of admixtures such as the air- entraining agents required to maintain the desirable air content while using micro silica is slightly higher than that required for conventional concrete. This is because of the high surface area in addition to the presence of carbon. Hence, the dosage of air entraining agents is increased with increasing amounts of micro silica content in concrete.
04. Effects on Water Requirements of Fresh Concrete
On adding silica fume to concrete, there is an automatic increase in water demand. This often results in requiring one additional pound of water for every pound of silica fume added. This issue can easily be solved by using High range water reducers (HRWR).
05. Effects on Consistency and Bleeding of Fresh Concrete
Adding more than 10% of silica fume in concrete induce stickiness in concrete. Therefore, in order to enhance the workability of concrete, the initial slump should be increased. It has been observed that condensed silica fume reduces the bleeding of concrete because of its effect on the rheological properties.
Applications of Micro Silica
Micro silica concrete is generally used to achieve following properties,
01. Corrosion Resistance
According to ‘Umesh Sharma et al.’ (Published in International Journal of Civil Engineering Research), the reduced permeability of micro-silica provides protection against intrusion of chloride ions thereby increasing the time taken for the chloride ions to reach the steel bar and initiate corrosion. In addition, micro-silica concrete has much higher electrical resistivity compared to OPC concrete thus slowing down the corrosion rate. This combined effect increases the life of a structure by 5 – 10 times.
- February 7, 2019
02. Sulphate Resistance
Silica fume concrete has a low susceptibility for penetration by sulphate ions and a high chemical resistance that provides a higher degree of protection against sulphates than low tricalcium aluminate (C3A) and other sulphate resisting cements or fly ash and other cementitious binder systems.
03. Heat Reduction
By replacing cement with condensed silica fume and observing its efficiency factor, a lower maximum temperature rise and temperature differential will take place for concrete with the same strength. The performance is better in comparison to slag and fly ash blends in case of thick sections. It is also proved to be the most effective way of achieving low heat concrete without compromising the strength at an early age.
- October 24, 2018
04. Abrasion Resistance
Abrasion resistance of Silica fume concrete is very high. The use of silica fume concrete in floor and pavement construction saves time and money. It also improves the operational efficiency for the facility operator. The hydraulic abrasion-erosion resistance of concrete is enhanced which makes it perfectly suitable for the construction of dam spillways.