Base should be compacted using a compactor rated to how many ft-lbf?

Base should be compacted using a compactor rated to how many ft-lbf?

• A. 7,000 lbf
• B. 5,000 lbf
• C. 9,000 lbf
• D. 12,000 lbf

Answer: (A)

Filling and stabilizing the base layer requires a specific amount of energy to densify the granular material without harming the underlying subgrade. That energy is measured in ft-lbf and comes from the plate’s weight and its drop height. For the base in interlocking concrete pavement, ICPI guidance uses a compactor rated about 7,000 ft-lbf. This level provides enough force to achieve the necessary density and uniform compaction across the base, helping to prevent future settlement and improve load transfer to the subgrade. Using a lower energy, around 5,000 ft-lbf, can leave the base under-compacted, leading to soft spots or creep under traffic. On the other hand, higher energies like 9,000 or 12,000 ft-lbf can over-work the base, potentially crushing fines or causing movement in the base that compromises stability. So 7,000 ft-lbf hits the balance between achieving proper density and preserving base integrity.

Filling and stabilizing the base layer requires a specific amount of energy to densify the granular material without harming the underlying subgrade. That energy is measured in ft-lbf and comes from the plate’s weight and its drop height. For the base in interlocking concrete pavement, ICPI guidance uses a compactor rated about 7,000 ft-lbf. This level provides enough force to achieve the necessary density and uniform compaction across the base, helping to prevent future settlement and improve load transfer to the subgrade.

Using a lower energy, around 5,000 ft-lbf, can leave the base under-compacted, leading to soft spots or creep under traffic. On the other hand, higher energies like 9,000 or 12,000 ft-lbf can over-work the base, potentially crushing fines or causing movement in the base that compromises stability. So 7,000 ft-lbf hits the balance between achieving proper density and preserving base integrity.