When it comes to constructing reinforced concrete structures, the most suitable size of aggregate to use is 20 mm. Generally, natural river sand is used as a fine aggregate, but in areas where it is not economically feasible, finely crushed stone can be used instead. Aggregates are used in concrete to reduce costs. They do not interact with cement and water.
The size of coarse-grained aggregates is the main factor in determining the strength of concrete. Generally, smaller coarse-grained aggregates are used for stronger concrete, with 20mm aggregates meeting the threshold for strong concrete and 40mm aggregates for normal strength concrete. Since fine aggregates are used to fill the voids of coarse-grained aggregates, the smaller the coarse-grained aggregates, the finer the fine aggregates should be. They increase the workability of concrete.
Only 15-34% of the aggregates in zone 1 will pass through a 0.6 mm screen; 35-59% of the aggregates in zone 2 will; 60-79% of zone 3 will; and 80-100% of zone 4 will. However, there are properties or characteristics of the aggregate that influence the properties of the resulting concrete mix. The added impact value provides a relative measure of the resistance of an aggregate to sudden shocks or impacts. This is the ideal size aggregate used in PCC, such as for pavement, road, walkway, or PCC driveway construction.
The presence of all these residues prevents adhesion between the aggregates and thus reduces the strength of the concrete. Recycled concrete can be a viable source of aggregate and has been successfully used in granular subbases, soil cement and new concrete. It's important to note that when referring to aggregate size, it means that most parts pass through a sieve of that size, not all. Aggregates have a major impact on freshly mixed and hardened concrete properties, mix ratios and economy. Therefore, it is necessary to test the aggregates to know if any of these constituents are present in them or not.
Some examples include fine aggregates and coarse-grained aggregates such as crushed stone, coarse-grained sand, medium sand, fine sand, silt, clay and fine gravel, medium gravel, coarse-grained gravel, pebbles, cobblestones and rocks. The aggregates obtained from such deposits are called gravel and sand while those produced from ledge rocks, boulders or cobblestones are known as crushed stone. The development of hard bond strength between aggregate particles and cement paste depends on surface texture, surface roughness and surface porosity of aggregate particles. If you're looking for medium strength concrete, get 40mm aggregates but if you're looking for high strength then 20mm is best. Leveling limits and maximum aggregate size are specified because these properties affect the amount of aggregate used as well as cement and water requirements, workability, pumpability and concrete durability. The void volume is equal to the difference between the gross volume of aggregate mass and volume occupied by particles alone.