Lesson 2/Learning Event 4
and highly compressive (CH). If the soil cannot be ribboned, it is nonplastic (ML or MH). If it can be
ribboned only with difficulty into short lengths, the soil is considered to have low plasticity (CL). The
roll test and the ribbon test complement each other in giving a clearer picture of the degree of plasticity
of soil. Figure 20 illustrates how the ribbon test is performed.
FIGURE 20. RIBBON TEST
BITE OR GRIT TEST
The bite and grit test is a quick and useful method of identifying sand, silt, or clay. In this test, a small
pinch of the soil material is ground lightly between the teeth and the soils identified as follows.
The sharp hard particles of sand will grate very harshly between the teeth and will be highly
objectionable. This is true even of the fine sand.