Materials Guide
Sand & Gravel Quality Guide for Cambodian Builders
BuildHub Team9 July 2026
How to test sand and gravel on site, what grades to use for concrete vs plaster, and where good aggregate is sourced in Cambodia.
Sand & Gravel Quality Guide for Cambodian Builders
Aggregates account for around 70% of concrete volume. Cheap, dirty sand is the single most common cause of cracked slabs in Cambodia.
Types of sand
- River sand (Mekong / Tonle Sap) — clean, well-graded, ideal for concrete and plaster.
- Pit sand — coarser, cheaper, good for backfill only.
- Sea sand — high salt content, do not use for reinforced concrete; corrodes rebar within a few years.
Quick on-site tests
Silt test. Fill a bottle 1/3 with sand, top up with water, shake, let settle 3 hours. The silt layer on top should be less than 6% of the sand volume.
Salinity test. Taste a pinch — if it is salty, reject it.
Gravel grades
| Grade | Size | Use |
|---|---|---|
| 3/4" (20 mm) | Small stones | Slabs, columns, beams |
| 1" (25 mm) | Medium | Foundations, mass concrete |
| 1.5"–2" | Large | Rip-rap, drainage |
Ordering tips
- Buy by weight (tonnes), not volume — trucks often under-fill.
- Check delivery for a written weight docket.
- Sand should be dry-ish; heavy moisture inflates the price you actually pay per kg of solids.
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