Aggregate is an important material for concrete and in the construction industry. It acts as the structural filler in the concrete. It is widely used for construction of house. Basically, the aggregates are crushed or uncrushed materials such as sand, gravels or stones, derived from the natural sources like river terraces, riverbeds, glacial deposits or rocks and boulders. It is used in the production of concrete for structural purposes including mass concrete works.
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Maximum size of aggregate mainly depends on the type of the structure and nature of the work. Use of larger size aggregate leads to higher strength. This is due to the fact that the larger the aggregate, the lower is the total surface area. Therefore, the lower is the requirement of water for the given workability. So, a lower water/cement ratio can be used which will result in higher strength of concrete.
Using the maximum size of aggregates in concrete will give you the following benefits:
01. Reduction of the cement content
02. Reduction in water requirement
03. Reduction of drying shrinkage
04. Reduction of void content
However, using maximum size of aggregate in any given condition may be restricted by the following conditions:
02. Spacing of reinforcement in all the structural element, i.e. distance between two bars
03. Clear cover in slabs, beams, columns, footings
04. Mixing, handling and placing techniques of concrete
Also Read: Size Wise Classification of Aggregate
The maximum size of aggregates generally used in concrete can be as large as possible within the specified limit. However, in any case, it should not greater than the minimum thickness of the structural member.
Usually, aggregates having a maximum size of 20 mm are generally considered satisfactory for reinforced concrete work, in normal residential work.