What to check in purchasing crush ?

Which qualities to be checked in crush.....Some crush looks white....Some dark grey....Some bluish....Which is best for strength? Beside colour some crush has khaka....Some has round stones....Some has brownish stones?What should be seen in purchasing?

Dear hamid, fine aggregates of margalla will be black and grey,crushed with sharp edges,washed and with out khaaka. Brown,white etc are mild stones they are not suit able for formwork. Round edges aggregate does't give a required strength. Presentation of brownish,white mild stones,khaka upto 5% having does not matter,don't worry. For inspection use a water glass and fill with aggregates and insert water into glass.all colours of aggregates and quantity of khaka can be seen.

Thnx a lot....ARMCO...this is what i was looking for...regards

Welcome @HAMID