Civil Engineering Reference
In-Depth Information
Figure 5.1
Soil particle sizes.
on your hands it will dust off while dry clay will leave your hands dirty and will have
to be washed off.
Soil particle shapes also differ considerably. Clay grains are usually plate-like while
silt, sand and gravel grains are more rotund.
Words such as sand, silt and clay are used both to classify a particular grain size and
to describe a soil which may contain lesser quantities of other sizes. The distribution
of particle sizes in a soil is represented by a grading curve on a particle size chart, as
shown in Fig. 5.2. If the grading curve is flat the soil contains a wide variety of different
particle sizes and is known to engineers as well graded; if the curve is steep and one size
Figure 5.2
Grading curves plotted on a particle size distribution chart. (After BS 1377:1990.)
