Today, silica fume is widely used in the construction industry because its strengths and weaknesses are accepted. What are the advantages and disadvantages of silica fume?
First, let’s understand the advantages of silica fume. Silica fume particles have an average diameter of less than 1 micron. Silica fume is a grey superfine powder with a density of 2.2g/cm³. Generally divided into densified silica fume and undensified silica fume, the bulk density of undensified silica fume is 200-350kg /m³, the bulk density of densified silica fume is 480-720kg /m³.
Silica fume is a property enhancing material, Silica fume advantages include the following:
1.Very low chloride ion diffusion
2.Increased compressive strength
3.Reduced water permeability
4.Improved sulfate resistance
5.Improved abrasion resistance
6.Improved resistance to chemical attack
7.Improved stability in geothermal environments
Silica fume disadvantages include
Due to the filling effect of silica fume, the moisture in concrete decreases and local dry shrinkage cracks are caused.Therefore, strengthening concrete maintenance after construction can effectively alleviate the problem.
If the external temperature is too high, it will cause the dry shrinkage of concrete surface. Before concrete condensation, if the surface water evaporation rate is higher than the bleeding rate, the dry shrinkage crack will appear on the surface.
The excessive amount of silica powder will reduce the constructability, make the concrete become compacted, and make the surface of construction difficult.