Recycled sand (RS) for concrete
Introduction
The granular material that is mainly used as raw material in construction is called aggregate.
Aggregate differs from other materials in its chemical stability and mechanical resistance, and is characterized by its size. Those mineral substances used as raw materials in industrial processes due to their chemical composition are not considered aggregates.
Guys
Depending on its origin, the aggregate can be natural, artificial or recycled.
Natural aggregate is that which comes from working a deposit and has been subjected only to mechanical processes.
Regarding their shape, they are distinguished as rounded (or rolled) and from crushing. The latter presents angular shapes due to the mechanical fracturing necessary to obtain it.
The rocks from which natural aggregates are extracted are:
Artificial aggregate is that which comes from an industrial process and has been subjected to some physical-chemical or other type of modification (such as clay).
Recycled aggregate is that which results from the recycling of demolition or construction waste and rubble.
Processes
The aggregate extracted from a quarry does not usually have the properties required on site, such as a defined granulometry, a maximum size or being free of fines, so it must be subjected to several processes for its implementation:
• - Cleaning: Branches, fines and other remains they may have are removed. It usually involves moistening them so in the end they will also have a subsequent drying if dry is required.
• - Crushed: To achieve the maximum necessary diameter, they must be broken with the crushers. Complete crushing has three phases. The primary one in which a 2 cm aggregate is produced, the secondary one in which the size ranges between 1.5 and 0.5 cm and the tertiary one that produces sand.
• - Classification: Depending on the diameter it can be done with screening, although if the diameter is less than 2 mm it is more profitable to use hydraulic and pneumatic separation.