Why are coarse and fine aggregate added to cement to make concrete?
Aggregates take up to 70-80% of the amount of concrete volume. Aggregates are considered mostly as filler material in the cement paste and have importance in making the concrete economical. Aggregate is less expensive as compared to cement hence it is used in a huge amount to bring down the cost of concrete.
Aggregate’s impact on different characteristics and properties of concrete is certainly huge. Properties of concrete include workability, durability, strength, weight and shrinkage. An aggregate provides body i.e. volume/mass of the concrete, reduces shrinkage and also help to achieve economy.
construction industry originally viewed aggregates as filler throughout the cement paste mainly for economic reason. Aggregate is cheaper than cement and it is, therefore, economical to put such a huge amount of aggregate in concrete.
But the economy is not the only reason for using aggregate. It’s higher volume stability and better durability than the hydrated cement paste alone, it is used worldwide. Earlier, aggregates were also considered as chemically inert materials. However, now it is found that some of the aggregates are chemically active and certain aggregates demonstrate the chemical bond at the interface of aggregates and paste. However, that solely depends upon the parent rock.
Without the study of the aggregates in depth and range, the knowledge of the concrete is incomplete. Cement is the only factory made the standard component in concrete. Other ingredients, such as water and aggregates are natural materials and can vary to any extent for many of their properties. Natural materials always tend to vary as per the location. To know more about the concrete, it is very essential that one should know more about the aggregates which constitute the major volume in concrete.
In other words, the aggregates are used to improve the economy, but more importantly, do contribute significantly to the final properties of any concrete mixture.