When it comes to building materials, good quality aggregates are essential. To be considered of high quality, aggregates must be clean, hard, strong, and have durable particles. Additionally, they must be free of any absorbed harmful chemicals, clay coatings, or other contaminants that could potentially affect cement hydration or reduce paste-aggregate bonding. The quality of an aggregate is determined by its physical and chemical properties. Physical properties include particle size, shape, surface texture, and porosity.
Chemical properties include composition and stability. The aggregate must also be free from any organic impurities that could cause deterioration or discoloration. The most important physical property of an aggregate is its particle size. The size of the particles affects the amount of water that can be absorbed by the aggregate. If the particles are too large, they will not absorb enough water to form a strong bond with the cement paste.
On the other hand, if the particles are too small, they will not provide enough strength to the concrete. The shape of the particles is also important. Angular particles provide better interlocking than rounded particles. This helps to create a stronger bond between the aggregate and the cement paste. Surface texture is another important factor in determining the quality of an aggregate. Smooth surfaces allow for better adhesion between the aggregate and the cement paste.
Rough surfaces can cause air pockets to form in the concrete, which can weaken its strength. Finally, porosity is an important factor in determining the quality of an aggregate. Porosity refers to how much air is trapped in the aggregate. If there is too much air trapped in the aggregate, it can reduce its strength and durability. In conclusion, good quality aggregates must be clean, hard, strong, have durable particles, and be free of absorbed harmful chemicals, clay coatings, or other contaminants that may affect cement hydration or reduce paste-aggregate bonding.