Silica fume concrete is a mixture of three, components: aggregate, paste and silica fume. The paste is made of cement and water, in which silica fume is added, and finally mixed with aggregates of different sizes.
In the form of silica fume concrete, concrete is a mixture of paste, silica fume and aggregate. The paste consists of Portland cement and water, which are filled with silica fume, which is wrapped around the surface of different sizes of aggregates, Through the chemical reaction of hydration, and finally forming a concrete that is as hard as stone.
In this process, the properties of silica fume play an important role. Increased strength and durability of concrete due to the addition of silica fume. Because of these advantages, people can build taller skyscrapers, longer bridges, and wider dams.
Want to get strong, durable concrete, the key is to carefully control the mixing proportion. If there is not enough paste in the concrete mixture, it will not be able to fill the voids of the aggregate, which will cause the aggregate to be exposed, porous and rough concrete. The result is that there are various quality problems with such concrete, posing a safety hazard.
The fresh concrete is workable by appropriate mixing ratio, so that the hardened concrete obtains the required strength and durability. Components of silica fume concrete: Cement 7%-15%,Water 14%-21%,Aggregates 60%-75%,Silica fume 1%-1.5%, Entrained air 5%-8%.
The quality of the paste determines the performance of concrete, and the water-cement ratio is the key to control the quality of the paste. The water–cement ratio is the ratio of the weight of water to the weight of cement used in a concrete mix. A lower ratio leads to higher strength and durability, but may make the mix difficult to work with and form.
Construction aggregate, or simply “aggregate”, Aggregates are usually divided into coarse aggregates and fine aggregates according to their size. Their main components are gravel or crushed stone.Sometime polypropylene fibers and metal scraps can also be used as an aggregate.
Silica fume is a very fine powder — the particles are approximately 1⁄100 the diameter of portland cement grains.When used to produce silica fume concrete, silica fume is typically 5-15% of the cement weight. Compared to the other ingredients in concrete, the amount of silica fume used is small. For the silica fume to be effective, two issues that must be addressed:
One: the agglomerations that make up the densified silica fume must be broken down.
Two: the silica fume must be distributed uniformly throughout the concrete.