Needle hole distribution apparatus

Standard: ASTM D4647, BS 1377:5

Dispersive Soils and Erosion Risk

Some soils that tend to disperse spontaneously in water are evaluated as "susceptible soils" in terms of erosion and piping. These soils are known in soil mechanics science as "dispersive clay or dispersive soils."

These soils, which are structurally unstable, can easily disperse and be highly susceptible to erosion. If dispersive clay soils are to be used in the construction of hydraulic structures, embankment dams, and road fills, they must be properly identified and constructed using appropriate techniques. Otherwise, serious engineering problems that can lead to landslides may be encountered.

Erosion resulting from the dispersibility of clay depends on the mineralogy and chemical composition of the clay, as well as the quality and quantity of dissolved salt content in the soil voids and in the water causing erosion.

Importance of the Test

This test technique allows for the simple classification of soil samples and determination of the quality of the soil sample.

Pinhole Test Apparatus

The pinhole test apparatus is used to determine the soil's susceptibility to erosion under water flow.