---
title: "Concrete — density, melting point and properties"
description: "Concrete has a density of 2,400 kg/m³ (2,200–2,500). Melting point, strength, conductivity, what it is used for, and whether it floats, rusts or is magnetic."
url: https://atoneplace.net/material/concrete/
site: "At One Place"
---

# Concrete

**Density of concrete: 2,400 kg/m³ (2,200–2,500)**

2.40 g/cm³ · 149.8 lb/ft³

The tensile figure of 2-5 MPa is the important one and the one nobody quotes: concrete carries 25-40 MPa in compression and roughly a tenth of that in tension, which is why every span of it has steel in the bottom. It gains strength by hydration, not drying — concrete cured underwater is stronger than concrete left in the sun — and it keeps gaining slowly for years past the 28-day test figure. Its thermal expansion coefficient happens to match steel almost exactly, which is the quiet coincidence that makes reinforced concrete possible at all.

## Properties

- **Density:** 2,400 kg/m³ (2,200–2,500) — 2.40 g/cm³
- **Tensile strength:** 2–5 MPa
- **Young's modulus:** 30 GPa
- **Thermal conductivity:** 1.4 W/(m·K)
- **Thermal expansion:** 10 µm/(m·K)
- **Floats in water:** No
- **Magnetic:** No

## What it is used for

- Foundations, slabs and footings
- Blockwork and paving
- Dams and retaining walls
- Precast pipes and lintels

## How it compares

*Water is 1,000 kg/m³. Anything with a shorter bar than water floats in it.*

- air: 1.2 kg/m³
- expanded polystyrene foam: 20 kg/m³
- rigid polyurethane foam: 40 kg/m³
- Water — the float line: 1,000 kg/m³
- concrete: 2,400 kg/m³
- tungsten: 19,250 kg/m³
- gold: 19,300 kg/m³
- platinum: 21,450 kg/m³

*Water is 1,000 kg/m³. Anything below that floats.*

| Material | Density | Relative to water |
| --- | --- | --- |
| rigid polyurethane foam | 40 kg/m³ | 0.04× |
| expanded polystyrene foam | 20 kg/m³ | 0.02× |
| air | 1.2 kg/m³ | 0.00× |
| concrete ← | 2,400 kg/m³ | 2.40× |
| platinum | 21,450 kg/m³ | 21.45× |
| gold | 19,300 kg/m³ | 19.30× |
| tungsten | 19,250 kg/m³ | 19.25× |

## Does it rust?

Concrete contains no iron, so it cannot rust. Whether it degrades depends on the material, not on oxidation.

## Is it magnetic?

Concrete is not a metal and has no ferromagnetic response.

## Common questions

### What is the density of concrete?

2,400 kg/m³ (2,200–2,500), or 2.40 g/cm³.

### Does concrete float?

No. At 2,400 kg/m³ it is denser than water.

### Is concrete magnetic?

Concrete is not a metal and has no ferromagnetic response.

## Related pages

- [Does concrete float?](https://atoneplace.net/does-it-float/concrete/)
- [Brick](https://atoneplace.net/material/brick/)
- [Gypsum board (drywall)](https://atoneplace.net/material/gypsum-board/)
- [Tungsten carbide](https://atoneplace.net/material/tungsten-carbide/)
- [Reinforced concrete](https://atoneplace.net/material/reinforced-concrete/)
- [Graphite](https://atoneplace.net/material/graphite/)
- [Porcelain](https://atoneplace.net/material/porcelain/)
- [Plaster](https://atoneplace.net/material/plaster/)
- [Silicon carbide](https://atoneplace.net/material/silicon-carbide/)

## Sources

- Typical range compiled from manufacturer specifications — At One Place (/about/)