Concrete plays an overwhelming role in our everyday life. Whether it is the building you reside, the office you work in, the bridge you pass by or the magnificent tower of Burj Khalifia in Dubai everything is made of concrete. However, concrete used in all these construction projects is not same. In fact, these projects use different concrete additives in different proportions. Why? because these additives mend the properties of concrete and make it more amenable to different functions.
Silica based concrete additives
While concrete additives are a necessity for making concrete amenable to different construction requirements and situations, they are not the same. There are different varieties of these additives. Among them one of the most commonly used are the Silica based concrete additives. These are a kind of additives which enhance the quality of concrete. In fact, these additives enhance the tensile strength, compressive strength, and impact strength of concrete and decrease the permeability of concrete to corrosive gasses.
What Are Corrosive Gasses
In construction projects carried out in saline environment, there is a strong likelihood of corrosive chlorides getting into concrete through its pores and corroding the underlying steel structure. Once it harms the inner structure it can weaken the whole structure. Silica based concrete additives can help stave off these attacks and sustain the structure such as in superstructures built near sea shores as in bridges and high-rise buildings.
Types of Concrete Additives
There are different types of concrete additives available in the market. However, you need to use only defined concrete additives for a given purpose. Broadly speaking, however, there are two types of concrete additives– chemical additives and mineral additives. The Silica based concrete additives are mineral additives which are obtained from different industrial and natural sources.
Properties of Silica Based Concrete Additives
These are used for bringing down permeability of concrete to various corrosive agents like chlorides. Structures in saline environment need such additives so that they can avert corrosion. However, these concrete additives also increase compressive strength of concrete which is a prerequisite for superstructures. They have the ability to modify basic properties of concrete such as hardening, setting time etc and make concrete amenable for use in major projects. These additives are mainly produced from fly ash, silica fumes etc. However, you can also procure them from nature such as from volcanic ash.
However, these additives need to be mixed with concrete in different proportions for different purposes. Projects that require high compressive strength may require a different proportion than projects that require less porosity.
- Additives By Function
Concrete additives may have different purposes as given below.
- Set retarding
These additives can delay setting of concrete by reducing the temperature.
- Air entrainment
These additives can improve resistance of concrete to severe frost and workability.
- Water reducing
These additives can help achieve desire concrete strength.
- Accelerating additives
These additives can reduce setting time of concrete.
- Shrinkage reducing
These additives can prevent long term shrinkage of concrete.
- Super plasticizers
These can enhance concrete slump and flow for reinforced structures.
- Corrosion inhibiting
These additives can inhibit steel corrosion over long periods of time.
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