It consists of small angular or round grains of silica and is formed by the decomposition of sandstone under the effect of weathering agencies. Sand is commonly used as a fine aggregate in the plain cement concrete. It may be either natural sand e.g. river sand, pit sand, and sea sand or artificial sand i.e. prepared by crushing stones and gravel to powder form.
Characteristics of Sand (Fine aggregate)
- Clean, sharp and angular
- Hard strong and durable.
- Chemically an inert material
- Highly silicious and free from impurities such as clay, loam, dust, coal particles and organic matter.
Functions of Sand
- It fills the voids present in the coarse aggregate.
- It assists in the hardening of cement by allowing water to penetrate through its voids.
- Help to minimizes shrinking and cracking of concrete.
- It prepares concrete economically, of any required strength, by varying its proportions.