The right sand in the concrete, and its silt checked
Why — act while you have leverage
Sand is bought by the load and nobody weighs it. Dirty sand or the wrong grade quietly weakens every batch it goes into, and there is nothing to see afterwards.
What to look at
- A jar silt test on each new load, done in front of the supplier
- The grading zone stated on the delivery note, not just "M sand"
- Sand stacked on a hard base, not on bare earth where it picks up soil
How to check it yourself
IS 383:2016 recognises crushed-stone (manufactured) sand alongside river sand and sorts fine aggregate into Zones I to IV — Zone II is the usual choice for reinforced concrete. Because crushing always makes more fine dust, the standard relaxes the 150 micron limit to 20 percent for crushed sand. The field test costs nothing: put sand and water in a glass jar, shake, let it settle, and look at the silt band that forms on top.
Where this comes from: IS 383:2016 — Coarse and fine aggregate for concrete (grading zones; manufactured sand) (indian standard or building code)