If you're building in Patna, your mason will ask for two kinds of sand at different times: Sone sand and Ganga sand. They look different, they cost different amounts, and they do different jobs. Mix them up and you either waste money or end up with weak work.
Here's a plain explanation, from people who sell sand every day.
The short answer
Use Sone sand for RCC: the slab, beams, columns and foundation concrete. Use Ganga sand for plaster, filling and, in many cases, brickwork. Most houses in Patna need both.
What is Ganga sand?
Ganga sand comes from the bed of the Ganga river around Patna. It's fine-grained and light grey to off-white in colour, which is why people sometimes call it white sand or safed balu. When you rub it between your fingers, it feels soft and smooth.
Because the grains are small, Ganga sand mixes into a smooth, workable mortar. That's exactly what you want on a wall. Plaster made with it is easy for the mason to spread and leaves a clean, even surface that takes putty and paint well.
What is Sone sand?
Sone sand comes from the Sone river, which meets the Ganga near Patna. It's coarser, with bigger, sharper grains, and it has a yellow to reddish colour. In Patna it's often just called lal balu or peela balu.
Those bigger grains are what concrete needs. In RCC, sand fills the gaps between stone chips and helps the cement bind everything into one strong mass. Coarse, well-graded sand does that job much better than fine sand.
Side-by-side comparison
| Ganga sand | Sone sand | |
|---|---|---|
| Colour | Light grey / off-white | Yellow to reddish |
| Grain | Fine and smooth | Coarse and sharper |
| Best for | Plaster, filling, brickwork, tile bedding | RCC: slab, beams, columns, foundation |
| Price | Usually lower | Usually higher |
Why not use Ganga sand for everything?
Because it's cheaper, some people are tempted to use Ganga sand in the slab as well. Don't. Fine sand in concrete needs more water and more cement to get the same strength, and if the mix isn't adjusted, the concrete can end up weaker. For a slab or column, that's not a risk worth taking to save a few thousand rupees.
And why not Sone sand for plaster?
You can plaster with Sone sand, but the coarser grain makes it harder to get a smooth finish, especially on the final coat. Many masons in Patna use Ganga sand for plaster for exactly this reason. Some like to mix a little Sone sand into the first (rough) coat, which is fine. Follow what your mason or engineer recommends.
What about brickwork?
This is where opinions differ. Plenty of masons in Patna use Ganga sand for brick walls, and it works well. Others prefer a mix of Ganga and Sone sand for a slightly stronger mortar. Either is common practice. Ask your mason which one he prefers, and order accordingly.
How to tell them apart when the load arrives
- Colour. Ganga sand is pale grey or whitish. Sone sand is clearly yellow or reddish.
- Feel. Ganga sand feels soft and fine. Sone sand feels gritty.
- Water test. Put a handful of either sand in a glass of water, stir it and leave it for a few minutes. If a thick layer of mud settles on top, the sand is dirty. This has nothing to do with Ganga or Sone. It's a sign of a poor-quality load.
How much of each will a house need?
It depends on the design, but as a rough idea, a typical house uses a large share of Sone sand during the structure stage (foundation, columns, slabs) and then mostly Ganga sand for brickwork, plaster and flooring. Plan your orders around the stages of work, so sand isn't sitting at your site for weeks and getting mixed with soil.
If you want a rough total for your house, read our guide: How Much Sand Do You Need to Build a House?
The bottom line
Sone sand for strength, Ganga sand for finish. Use each where it belongs, and you'll get a stronger house and a better-looking one, without wasting money on the wrong load.