Why good quality sand is never obtained from the sea?

River sand vs. Sea sand:
- River sand is generally considered to be of better quality than sea sand for construction purposes.
- Sea sand contains salt which can corrode metals used in construction.
- Sea sand may also contain impurities like shells and organic matter which can weaken the concrete.

Factors affecting sand quality:
- The shape and texture of sand particles play a crucial role in determining its quality.
- Sand with round and smooth particles is considered to be of higher quality compared to angular and rough particles.
- The presence of impurities like clay, silt, and organic matter can also affect the quality of sand.

Nala sand vs. Sea sand:
- Nala sand refers to sand obtained from streams or small rivers.
- Nala sand is typically cleaner and better quality compared to sea sand as it is less likely to contain impurities like salt, shells, and organic matter.
- Nala sand is often preferred for construction purposes due to its better quality and suitability for use in concrete.
In conclusion, good quality sand is never obtained from the sea due to the presence of salt, impurities, and the inferior quality of sand particles. Nala sand, on the other hand, is considered to be of better quality and more suitable for construction purposes.