• Hammer weight: 2.5 kg (5.5 lb)
• Drop height: 305 mm (12 in)
• No. of layers: 3
• Blows per layer: 25
• Energy: $600 \, kN-m/m^3$ ($12,400 \, ft-lb/ft^3$)

• Hammer weight: 4.54 kg (10 lb)
• Drop height: 457 mm (18 in)
• No. of layers: 5
• Blows per layer: 25
• Energy: $2,700 \, kN-m/m^3$ ($56,000 \, ft-lb/ft^3$)
• Used for higher load applications (airfields, highways).

A plot of dry unit weight ($\gamma_d$) vs. water content ($w$).

• Maximum Dry Unit Weight ($\gamma_{d,max}$): The peak of the curve.
• Optimum Moisture Content (OMC): The water content at which $\gamma_{d,max}$ is achieved.
• Zero Air Voids (ZAV) Curve: Theoretical maximum density where $S=100\%$. $\gamma_{zav} = \frac{G_s \gamma_w}{1 + w G_s}$

Used to verify if the required compaction is achieved in the field.

• Sand Cone Method
• Rubber Balloon Method
• Nuclear Density Gauge

The ratio of field dry unit weight to the maximum laboratory dry unit weight. $R = \frac{\gamma_{d,field}}{\gamma_{d,max-lab}} \times 100\%$ Typical specification: $R \ge 95\%$.