When it comes to producing quality concrete, selecting the right aggregate is essential. Good quality aggregate must be clean, hard, strong, and free of absorbed harmful chemicals, clay coatings, or other contaminants that may affect cement hydration or reduce paste-aggregate bonding. Aggregates greatly influence freshly mixed and hardened concrete properties, mix ratios and economy. The ideal construction aggregate should have a rough surface texture and be clean, strong and free of coating and other dirt particles.
Coarse-grayed aggregates with a size of 20 mm or less are commonly used for most concrete constructions. Observations and field tests can be used to check the quality of aggregates and choose the right aggregate to produce concrete. The texture of the surface, the shape of the particles and the cleanliness of the coarse-grained aggregate can be roughly checked only by visual observation. 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.
Recycled concrete is a viable source of aggregate and has been successfully used in granular subbases, soil cement and new concrete. When specifying void graded aggregates, certain particle sizes are omitted from the aggregate of the size continuum. To ensure good quality concrete is produced, it is important to handle and store aggregates properly to minimize segregation and degradation and prevent contamination.