Washed Sand vs Natural Sand: Differences and When to Use Each
By David Polido, CEO of Chambino Areias and INERCORChambino Areias supplies sand in Portugal only (Seixal, near Lisbon). Prices exclude VAT; delivery to site from 5 t across the Lisbon and Setúbal region; smaller orders are collected at the pit.
Introduction
When planning a construction project, choosing between washed sand and natural (pit) sand is a crucial decision that impacts the quality, durability and cost of the work. In this guide, we compare the differences, advantages and disadvantages of each type to help you choose for your project.
What is Washed Sand?
Washed sand is an aggregate that undergoes an industrial washing process to remove impurities such as clay, silt, organic materials and part of the fine particles, which can interfere with cement setting.
Washing Process (general outline; it varies from plant to plant):
- Extraction: Sand is extracted from pits or river beds
- Screening: First separation by grain size
- Washing: Water removes clay, silt and organic matter
- Drainage: Removal of excess water
- Classification: Final separation by grain size (0/1, 0/4, etc.)
Characteristics of Washed Sand:
- Free of clay and organic matter
- Clean grains without coatings
- Controlled grain size
- At Chambino: CE marking under EN 12620
What is Natural (Pit) Sand?
Natural sand, popularly known as pit sand, is extracted from land deposits (pits) instead of river beds and is used as it comes out of extraction, without washing.
It is important to distinguish between two things. A generic unwashed natural sand, from an unknown origin, may carry clay, lumps and organic matter, and may have no CE marking at all. Our pit sand 0/4, extracted at our own pit in Seixal, has CE marking under EN 12620, with a Declaration of Performance (DoP) available on request, so the technician can check on the DoP whether its declared values suit the project.
Natural does not have to mean dirty: Tagus River sand is also a natural sand, naturally clean of clay and organic matter without industrial washing, with rounded grains and CE marking under EN 12620 (big bag €25, excl. VAT).
Characteristics of Generic Unwashed Sand:
- May contain clay and fines
- Variable grain size
- May contain organic matter
- CE marking depends on the supplier: always ask for it
Chambino Pit Sand 0/4:
- Grain size 0/4 mm
- CE marking under EN 12620, Declaration of Performance on request
- Big bag: €24 · 25 kg bag: €1 (excl. VAT)
- Uses: fills, bedding and levelling layers, pipe bedding, ordinary non-structural mortars, outdoor works
Direct Comparison
| Criterion | Washed Sand 0/4 | Chambino Pit Sand 0/4 |
|---|---|---|
| Processing | Washed: free of clay and organic matter | Unwashed, used as extracted |
| Price (big bag, excl. VAT) | €24 | €24 |
| Price (25 kg bag, excl. VAT) | €0.85 | €1 |
| CE Marking | ✓ Yes (EN 12620) | ✓ Yes (EN 12620) |
| Best for | Screeds, concrete, masonry mortars, exposed work | Fills, bedding layers, levelling, hidden work |
Advantages and Disadvantages
Washed Sand
✓ Advantages:
- Free of clay and organic matter
- Low fines content, which helps cement setting and reduces shrinkage
- Consistent grading
✗ Disadvantages:
- Often more expensive on the market; at Chambino it is not: the big bag costs the same (€24) and the 25 kg bag of washed 0/4 is cheaper (€0.85 vs €1)
Pit Sand
✓ Advantages:
- Used as extracted, with no washing step
- Good for fills and bedding layers
- Chambino pit sand 0/4: CE marking under EN 12620
✗ Disadvantages:
- May contain more fines than washed sand, so mortars may need more cement
- At Chambino, not sold in bulk: for volume work, washed 0/4 in bulk (€9.25/t, from 5 t) is usually the cheaper option
- Rougher result in exposed or finishing work
- Generic unwashed sand may contain clay or organic matter and may have no CE marking
When to Use Each Type?
Use Washed Sand in:
- Screeds and floors: washed coarse sand 0/4, mix of about 1:3 to 1:4 (cement:sand)
- Concrete: structural and non-structural
- Masonry mortars: laying blocks and bricks
- Renders: washed fine sand 0/1, mix of about 1:5 to 1:6
- Exposed or load-bearing work: where the sand carries load or stays visible
Use Pit Sand in:
- Fills: trenches, excavations, backfills
- Bedding and levelling layers
- Pipe and box bedding
- Ordinary non-structural mortars
- Outdoor works: landscaping and terrain levelling
Rule of thumb: where the sand stays hidden, pit sand pays off; where it stays visible or carries load, choose washed sand. In any work that requires CE-marked aggregates, ask for the Declaration of Performance: all Chambino sands, including pit sand 0/4, have CE marking under EN 12620.
Cost
At Chambino Areias, a big bag of washed sand 0/4 costs €24 and one of pit sand 0/4 costs €24 (excl. VAT); in 25 kg bags, €0.85 and €1. The big bag costs the same and the 25 kg bag of washed sand is cheaper. For volume work, washed 0/4 is the only sand sold in bulk, at €9.25/t (excl. VAT, from 5 t). So the choice is about the application, not the price.
Final Conclusion
The choice between washed sand and pit sand should be based on the type of work. For screeds, concrete and exposed or finishing work, choose washed sand. For fills, bedding layers and hidden work, pit sand is the practical option.
At Chambino Areias, all our sands (washed coarse 0/4, washed fine 0/1, pit sand 0/4 and Tagus River sand) have CE marking under EN 12620, with a Declaration of Performance available on request. Our washed gravel 8-12 mm has no CE marking and is for non-structural uses only.