Falling Head Permeability Device

The falling head permeability device is used to determine the rate of flow of water through a compacted HMA sample. Water in a graduated cylinder is allowed to flow through a saturated asphalt sample and the interval of time taken to reach a known change in head is recorded. The coefficient of permeability of the asphalt sample is then determined based on Darcy’s Law. (Figure 9)

Figure 9 – Falling Head Permeability (4 and 6 Inch Diameter) for Asphalt Samples