| Type | Aggregate | Minimum Compressive Strength | Typical Density | |------|-----------|-----------------------------|------------------| | | Normal weight (gravel, crushed stone) | 35 MPa (after 28 days) | 2240–2400 kg/m³ | | Type B | Heavyweight (magnetite, hematite, barite) | 35 MPa | >3040 kg/m³ |