In the Standard Proctor test, the energy is expressed as which value?

In the Standard Proctor test, the energy is expressed as which value?

• A. 56,200 ft lbs
• B. 25 blows per layer
• C. 3 layers
• D. 12,400 ft lbs

Answer: (D)

In this test, energy is the fixed amount of energy input per unit volume delivered to the soil during compaction. For the Standard Proctor, that energy is 12,400 ft-lbf per cubic foot (often written as 12,400 ft-lbf/ft^3). This value comes from using a lighter hammer dropped a short height with a specific number of blows per layer across a set number of layers. The Modified Proctor uses a higher energy input, about 56,250 ft-lbf/ft^3, due to a heavier hammer and greater drop height. The other options describe the procedure (number of blows per layer, number of layers) or point to the higher energy of the Modified Proctor, not the Standard one. So the correct energy expression for the Standard Proctor is 12,400 ft-lbf/ft^3.

In this test, energy is the fixed amount of energy input per unit volume delivered to the soil during compaction. For the Standard Proctor, that energy is 12,400 ft-lbf per cubic foot (often written as 12,400 ft-lbf/ft^3). This value comes from using a lighter hammer dropped a short height with a specific number of blows per layer across a set number of layers. The Modified Proctor uses a higher energy input, about 56,250 ft-lbf/ft^3, due to a heavier hammer and greater drop height. The other options describe the procedure (number of blows per layer, number of layers) or point to the higher energy of the Modified Proctor, not the Standard one. So the correct energy expression for the Standard Proctor is 12,400 ft-lbf/ft^3.