There has been a long-term growing demand for aggregates to produce concrete and this has presented increased problems of supplying of sand and gravel. Besides this, environmental rules and regulations and scarcity of natural aggregates result in a continuously increasing trend towards the use of crushed stone aggregates in concrete.
Crushed stone aggregates are more suitable for production of high strength concrete compared to natural gravel and sand. Crushed stone aggregates differ from sand and gravel in particle shape and surface texture and in the grading of fines. the grading requirements of crushed stone fine aggregate which is slightly different than that of the natural sand. The difference is related to the very fine particles, often referred to as “crushed stone dust” or simply “dust”, i.e. particles passing 75 pm BS test sieve.
Some standard allows a dust content of up to 15%t by mass for crushed stone fine aggregates and 10% by mass for crushed stone all-in aggregates. If there is a reluctance to use crushed stone aggregates in concrete manufacturing, it is primarily based on this allowance of a higher dust content in crushed stone fines than that in the natural sand.