River sand has become scarce and expensive in many Indian states because of restrictions on sand mining. Manufactured sand, or M-sand, made by crushing hard rock, has largely taken its place. Used correctly, it performs very well. Used without checking, it can cause trouble.
How M-sand is made
Hard granite or basalt is crushed in stages and then shaped in a vertical shaft impactor, which knocks off sharp edges to make more cubical particles. The product is washed or air-classified to remove excess fine dust, and graded to a consistent particle size range.
River sand vs M-sand
| River sand | M-sand (good quality) | |
|---|---|---|
| Particle shape | Rounded, smooth | Cubical, rough-textured |
| Silt and clay | Often present, varies by source | Very low if washed |
| Grading | Varies | Consistent |
| Bond with cement | Good | Very good, thanks to rough surface |
| Workability | Easier to work | Needs slightly more water or a plasticiser |
| Availability | Restricted in many areas | Widely available |
Concrete sand vs plaster sand
M-sand is usually sold in two grades. Coarser sand, sometimes called concrete sand, is for concrete and masonry. Finer plaster sand gives a smoother finish for plastering. Using coarse sand for plaster gives a rough surface and more cracking.
How to check M-sand quality
- Rub test: rub wet sand between your palms. Lots of fine powder sticking to your hands means excess dust.
- Shape: particles should look cubical, not flat and flaky.
- Silt test: the bottle test described in our field tests guide works for M-sand too.
- Consistency: buy from a plant that can provide test reports, and check that lorries look the same from load to load.
Tips for using M-sand
- Do not add extra water to make the mix flow. Use a plasticiser instead.
- Cure carefully. Mortar with dusty M-sand is prone to shrinkage cracks.
- For plaster, use plaster-grade M-sand, not the coarse concrete grade.
Frequently asked questions
Is M-sand allowed by Indian Standards?
Yes. The standard for concrete aggregates includes manufactured and crushed sand, with limits on grading and fine content.
Is M-sand cheaper?
In many regions it is now cheaper and more reliably available than river sand, though prices vary by location.