Learn free Civil Engineering by Civilustaad about FINE AGGREGATE

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FINE AGGREGATE

It is the aggregate the majority of which passes 4.75 mm IS sieve and contains only so much coarser as is permitted by specification. According to source fine aggregate might be described as:

Natural Sand– it is the aggregate resulting from the natural breakdown of rock and which has been deposited by streams or glacial agenciesCrushed Stone Sand– it is the fine aggregate created by crushing hard stone.
Crushed Gravel Sand– it is the fine aggregate formed by crushing natural gravel.

According to size the fine aggregate may be described as coarse sand, medium sand and fine sand. IS specifications categorize the fine aggregate into four types according to its grading as fine aggregate of grading Zone-1 to grading Zone-4.

The four grading zones become gradually finer from grading Zone-1 to grading Zone-4. 90% to 100% of the fine aggregate passes 4.75 mm IS sieve and 0 to 15% passes 150 micron IS sieve depending upon its grading zone.

Learn free Civil Engineering by Civilustaad about CONCRETE CRIB WALLS

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CONCRETE CRIB WALLS

Concrete crib walls are gravity retaining walls, constructed from interlocking, precast, concrete mechanism. 

 They are filled with free draining material and earth backfill to get rid of the hazards of hydrostatic pressure building up behind the wall.

 Concrete crib walls are little cost, of open web construction, and can be rapidly and inexpensively erected. They can be used roughly anywhere a retaining wall is needed – as well as driveways, building sites, and garden areas.