Chapter 5, Problem 5.9P

To determine

Find the classification of the given soil using unified soil classification system and give the group symbols and group names.

Answer to Problem 5.9P

The classification of soil 1 using unified soil classification system is $\underset{\_}{\text{Clayey}\text{sand with gravel}}$.

The group symbol of the soil 1 is $\underset{\_}{\text{SC}}$.

The classification of soil 2 using unified soil classification system is $\underset{\_}{\text{Clayey}\text{gravel with sand}}$.

The group symbol of the soil 2 is $\underset{\_}{\text{GC}}$.

The classification of soil 3 using unified soil classification system is $\underset{\_}{\text{Sandy}\text{fat clay}}$.

The group symbol of the soil 3 is $\underset{\_}{\text{CH}}$.

The classification of soil 4 using unified soil classification system is $\underset{\_}{\text{Lean clay with sand}}$.

The group symbol of the soil 4 is $\underset{\_}{\text{CL}}$.

The classification of soil 5 using unified soil classification system is $\underset{\_}{\text{Lean clay with sand}}$.

The group symbol of the soil 5 is $\underset{\_}{\text{CL}}$.

The classification of soil 6 using unified soil classification system is $\underset{\_}{\text{Clayey sand}}$.

The group symbol of the soil 6 is $\underset{\_}{\text{SC}}$.

The classification of soil 7 using unified soil classification system is $\underset{\_}{\text{Fat clay with gravel}}$.

The group symbol of the soil 7 is $\underset{\_}{\text{CH}}$.

The classification of soil 8 using unified soil classification system is $\underset{\_}{\text{Sandy}\text{fat clay}}$.

The group symbol of the soil 8 is $\underset{\_}{\text{CH}}$.

The classification of soil 9 using unified soil classification system is $\underset{\_}{\text{Poorly graded}\text{sand with clay and gravel}}$.

The group symbol of the soil 9 is $\underset{\_}{\text{SP-SC}}$.

The classification of soil 10 using unified soil classification system is $\underset{\_}{\text{Well graded}\text{sand}}$.

The group symbol of the soil 10 is $\underset{\_}{\text{SW}}$.

The classification of soil 11 using unified soil classification system is $\underset{\_}{\text{Sandy}\text{lean clay}}$.

The group symbol of the soil 11 is $\underset{\_}{\text{CL}}$.

The classification of soil 12 using unified soil classification system is $\underset{\_}{\text{Poorly graded}\text{sand with clay}}$.

The group symbol of the soil 12 is $\underset{\_}{\text{SP-SC}}$.

Explanation of Solution

Calculation:

For soil 1:

The plasticity index (PI) is 21.

Determine the coarse fraction.

$\text{Coarse}\text{fraction}=100-\text{percent}\text{passing}\text{on}\text{No}\text{.200}\text{seive}$ (1)

Substitute 30 % for percent retained on No.200 sieve in Equation (1).

$\begin{array}{c}\text{Coarse}\text{fraction}=100-\text{30}\\ =\text{70}\text{\%}\end{array}$

Determine the gravel fraction.

$\text{Gravel}\text{fraction}=100-\text{percent}\text{passing}\text{on}\text{No}\text{.4}\text{seive}$ (2)

Substitute 70 % for percent passing No.4 sieve in Equation (2).

$\begin{array}{c}\text{Gravel}\text{fraction}=100-70\\ =3\text{0\%}\end{array}$

Determine the sand fraction using the relation.

$\text{Sand}\text{fraction}=\text{Percent}\text{of}\text{coarse}\text{fraction}-\text{Percent}\text{of}\text{gravel}\text{fraction}$ (3)

Substitute 70 % for percent of coarse fraction 30 % for percent of coarse fraction in Equation (3).

$\begin{array}{c}\text{Sand}\text{fraction}=70-30\\ =40\%\end{array}$

Refer Table 5.2 “Unified soil classification system” and Figure 5.3 “Plasticity chart” in the text book.

The group symbol of the soil can be taken as $\underset{\_}{\text{SC}}$.

Provide the group name of soil as shown below.

The gravel fraction $30\%$ is $\ge 15\%$.

Refer Figure 5.4 “Flowchart group names for gravelly and sandy soil” in the text book.

Take the group name as clayey sand with gravel for the group of SC and gravel fraction of $\ge 15\%$.

Thus, the classification of soil 1 using unified soil classification system is $\underset{\_}{\text{Clayey}\text{sand with gravel}}$.

For soil 2:

The plasticity index (PI) is 22.

Determine the coarse fraction as shown below.

Substitute 20 % for percent retained on No.200 sieve in Equation (1).

$\begin{array}{c}\text{Coarse}\text{fraction}=100-2\text{0}\\ =80\text{\%}\end{array}$

Determine the gravel fraction as shown below.

Substitute 48 % for percent passing No.4 sieve in Equation (2).

$\begin{array}{c}\text{Gravel}\text{fraction}=100-48\\ =52\text{\%}\end{array}$

Determine the sand fraction using the relation.

Substitute 80 % for percent of coarse fraction 52 % for percent of coarse fraction in Equation (3).

$\begin{array}{c}\text{Sand}\text{fraction}=80-52\\ =28\%\end{array}$

Refer Table 5.2 “Unified soil classification system” and Figure 5.3 “Plasticity chart” in the text book.

The group symbol of the soil can be taken as $\underset{\_}{\text{GC}}$.

Provide the group name of soil as shown below.

The sand fraction $28\%$ is $\ge 15\%$.

Refer Figure 5.4 “Flowchart group names for gravelly and sandy soil” in the text book.

Take the group name as clayey gravel with sand for the group of GC and sand fraction of $\ge 15\%$.

Thus, the classification of soil 2 using unified soil classification system is $\underset{\_}{\text{Clayey}\text{gravel with sand}}$.

For soil 3:

The plasticity index (PI) is 28.

Determine the coarse fraction as shown below.

Substitute 70 % for percent retained on No.200 sieve in Equation (1).

$\begin{array}{c}\text{Coarse}\text{fraction}=100-70\\ =30\text{\%}\end{array}$

Determine the gravel fraction as shown below.

Substitute 95 % for percent passing No.4 sieve in Equation (2).

$\begin{array}{c}\text{Gravel}\text{fraction}=100-95\\ =5\text{\%}\end{array}$

Determine the sand fraction using the relation.

Substitute 30 % for percent of coarse fraction 5 % for percent of coarse fraction in Equation (3).

$\begin{array}{c}\text{Sand}\text{fraction}=30-5\\ =25\%\end{array}$

Refer Table 5.2 “Unified soil classification system” in the text book.

The soil is a fine-grained soil.

Refer Table 5.2 “Unified soil classification system” and Figure 5.3 “Plasticity chart” in the text book.

The group symbol of the soil can be taken as $\underset{\_}{\text{CH}}$.

Provide the group name of soil as shown below.

Refer Figure 5.5 “Flowchart group names for inorganic silty and clayey soil” in the text book.

Take the group name as sandy fat clay for the group of CH, $\ge 30\%$ plus No.200, $\%\text{sand}\ge \%\text{gravel}$, and $<15\%\text{gravel}$.

Thus, the classification of soil 3 using unified soil classification system is $\underset{\_}{\text{Sandy}\text{fat clay}}$.

For soil 4:

The plasticity index (PI) is 19.

Determine the coarse fraction as shown below.

Substitute 82 % for percent retained on No.200 sieve in Equation (1).

$\begin{array}{c}\text{Coarse}\text{fraction}=100-82\\ =18\text{\%}\end{array}$

Determine the gravel fraction as shown below.

Substitute 100 % for percent passing No.4 sieve in Equation (2).

$\begin{array}{c}\text{Gravel}\text{fraction}=100-100\\ =0\end{array}$

Determine the sand fraction using the relation.

Substitute 18 % for percent of coarse fraction 0 for percent of coarse fraction in Equation (3).

$\begin{array}{c}\text{Sand}\text{fraction}=18-0\\ =18\%\end{array}$

Refer Table 5.2 “Unified soil classification system” in the text book.

The soil is a fine-grained soil.

Refer Table 5.2 “Unified soil classification system” and Figure 5.3 “Plasticity chart” in the text book.

The group symbol of the soil can be taken as $\underset{\_}{\text{CL}}$.

Provide the group name of soil as shown below.

Refer Figure 5.5 “Flowchart group names for inorganic silty and clayey soil” in the text book.

Take the group name as lean clay with sand for the group of CL.

Thus, the classification of soil 4 using unified soil classification system is $\underset{\_}{\text{Lean clay with sand}}$.

For soil 5:

The plasticity index (PI) is 21.

Determine the coarse fraction as shown below.

Substitute 74 % for percent retained on No.200 sieve in Equation (1).

$\begin{array}{c}\text{Coarse}\text{fraction}=100-72\\ =26\text{\%}\end{array}$

Determine the gravel fraction as shown below.

Substitute 100 % for percent passing No.4 sieve in Equation (2).

$\begin{array}{c}\text{Gravel}\text{fraction}=100-100\\ =0\end{array}$

Determine the sand fraction using the relation.

Substitute 26 % for percent of coarse fraction 0 for percent of coarse fraction in Equation (3).

$\begin{array}{c}\text{Sand}\text{fraction}=26-0\\ =26\%\end{array}$

Refer Table 5.2 “Unified soil classification system” in the text book.

The soil is a fine-grained soil.

Refer Table 5.2 “Unified soil classification system” and Figure 5.3 “Plasticity chart” in the text book.

The group symbol of the soil can be taken as $\underset{\_}{\text{CL}}$.

Provide the group name of soil as shown below.

Refer Figure 5.5 “Flowchart group names for inorganic silty and clayey soil” in the text book.

Take the group name as lean clay with sand for the group of CL.

Thus, the classification of soil 5 using unified soil classification system is $\underset{\_}{\text{Lean clay with sand}}$.

For soil 6:

The plasticity index (PI) is 18.

Determine the coarse fraction as shown below.

Substitute 26 % for percent retained on No.200 sieve in Equation (1).

$\begin{array}{c}\text{Coarse}\text{fraction}=100-26\\ =74\text{\%}\end{array}$

Determine the gravel fraction as shown below.

Substitute 87 % for percent passing No.4 sieve in Equation (2).

$\begin{array}{c}\text{Gravel}\text{fraction}=100-87\\ =13\text{\%}\end{array}$

Determine the sand fraction using the relation.

Substitute 74 % for percent of coarse fraction 13 % for percent of coarse fraction in Equation (3).

$\begin{array}{c}\text{Sand}\text{fraction}=74-13\\ =61\%\end{array}$

Refer Table 5.2 “Unified soil classification system” and Figure 5.3 “Plasticity chart” in the text book.

The group symbol of the soil can be taken as $\underset{\_}{\text{GC}}$.

Provide the group name of soil as shown below.

The gravel fraction $13\%$ is $<15\%$.

Refer Figure 5.4 “Flowchart group names for gravelly and sandy soil” in the text book.

Take the group name as clayey sand for the group of GC and sand fraction of $<15\%$.

Thus, the classification of soil 6 using unified soil classification system is $\underset{\_}{\text{Clayey sand}}$.

For soil 7:

The plasticity index (PI) is 38.

Determine the coarse fraction.

Substitute 78 % for percent retained on No.200 sieve in Equation (1).

$\begin{array}{c}\text{Coarse}\text{fraction}=100-78\\ =22\text{\%}\end{array}$

Determine the gravel fraction.

Substitute 88 % for percent passing No.4 sieve in Equation (2).

$\begin{array}{c}\text{Gravel}\text{fraction}=100-88\\ =12\text{\%}\end{array}$

Determine the sand fraction using the relation.

Substitute 22 % for percent of coarse fraction 12 % for percent of coarse fraction in Equation (3).

$\begin{array}{c}\text{Sand}\text{fraction}=22-12\\ =10\%\end{array}$

Refer Table 5.2 “Unified soil classification system” in the text book.

The soil is a fine-grained soil.

Refer Table 5.2 “Unified soil classification system” and Figure 5.3 “Plasticity chart” in the text book.

The group symbol of the soil can be taken as $\underset{\_}{\text{CH}}$.

Provide the group name of soil as shown below.

Refer Figure 5.5 “Flowchart group names for inorganic silty and clayey soil” in the text book.

Take the group name as fat clay with gravel for the group of CH, $<30\%$ plus No.200, and $\%\text{sand}<\%\text{gravel}$.

Thus, the classification of soil 7 using unified soil classification system is $\underset{\_}{\text{Fat clay with gravel}}$.

For soil 8:

The plasticity index (PI) is 26.

Determine the coarse fraction as shown below.

Substitute 57 % for percent retained on No.200 sieve in Equation (1).

$\begin{array}{c}\text{Coarse}\text{fraction}=100-57\\ =43\text{\%}\end{array}$

Determine the gravel fraction as shown below.

Substitute 99 % for percent passing No.4 sieve in Equation (2).

$\begin{array}{c}\text{Gravel}\text{fraction}=100-99\\ =1\text{\%}\end{array}$

Determine the sand fraction using the relation.

Substitute 43 % for percent of coarse fraction 1 % for percent of coarse fraction in Equation (3).

$\begin{array}{c}\text{Sand}\text{fraction}=43-1\\ =42\%\end{array}$

Refer Table 5.2 “Unified soil classification system” in the text book.

The soil is a fine-grained soil.

Refer Table 5.2 “Unified soil classification system” and Figure 5.3 “Plasticity chart” in the text book.

The group symbol of the soil can be taken as $\underset{\_}{\text{CH}}$.

Provide the group name of soil as shown below.

Refer Figure 5.5 “Flowchart group names for inorganic silty and clayey soil” in the text book.

Take the group name as sandy fat clay for the group of CH, $\ge 30\%$ plus No.200, $\%\text{sand}\ge \%\text{gravel}$, and $<15\%\text{gravel}$.

Thus, the classification of soil 8 using unified soil classification system is $\underset{\_}{\text{Sandy}\text{fat clay}}$.

For soil 9:

The plasticity index (PI) is 16.

Determine the coarse fraction as shown below.

Substitute 11 % for percent retained on No.200 sieve in Equation (1).

$\begin{array}{c}\text{Coarse}\text{fraction}=100-11\\ =89\text{\%}\end{array}$

Determine the gravel fraction as shown below.

Substitute 71 % for percent passing No.4 sieve in Equation (2).

$\begin{array}{c}\text{Gravel}\text{fraction}=100-71\\ =29\text{\%}\end{array}$

Determine the sand fraction using the relation.

Substitute 89 % for percent of coarse fraction 29 % for percent of coarse fraction in Equation (3).

$\begin{array}{c}\text{Sand}\text{fraction}=89-29\\ =60\%\end{array}$

Refer Table 5.2 “Unified soil classification system” and Figure 5.3 “Plasticity chart” in the text book.

The group symbol of the soil can be taken as $\underset{\_}{\text{SP-SC}}$.

Provide the group name of soil as shown below.

Refer Figure 5.4 “Flowchart group names for gravelly and sandy soil” in the text book.

Take the group name as poorly graded sand with clay and gravel for the group of SP-SC and gravel fraction of $\ge 15\%$.

Thus, the classification of soil 9 using unified soil classification system is $\underset{\_}{\text{Poorly graded}\text{sand with clay and gravel}}$.

For soil 10:

Determine the coarse fraction as shown below.

Substitute 2 % for percent retained on No.200 sieve in Equation (1).

$\begin{array}{c}\text{Coarse}\text{fraction}=100-2\\ =98\text{\%}\end{array}$

Determine the gravel fraction as shown below.

Substitute 100 % for percent passing No.4 sieve in Equation (2).

$\begin{array}{c}\text{Gravel}\text{fraction}=100-100\\ =0\end{array}$

Determine the sand fraction using the relation.

Substitute 98 % for percent of coarse fraction 0 for percent of coarse fraction in Equation (3).

$\text{Sand}\text{fraction}=98\%$

Refer Table 5.2 “Unified soil classification system” and Figure 5.3 “Plasticity chart” in the text book.

The group symbol of the soil can be taken as $\underset{\_}{\text{SW}}$.

Provide the group name of soil as shown below.

Refer Figure 5.4 “Flowchart group names for gravelly and sandy soil” in the text book.

Take the group name as well graded sand for the group of SW and gravel fraction of $<15\%$.

Thus, the classification of soil 10 using unified soil classification system is $\underset{\_}{\text{Well graded}\text{sand}}$.

For soil 11:

The plasticity index (PI) is 21.

Determine the coarse fraction as shown below.

Substitute 65 % for percent retained on No.200 sieve in Equation (1).

$\begin{array}{c}\text{Coarse}\text{fraction}=100-65\\ =35\text{\%}\end{array}$

Determine the gravel fraction as shown below.

Substitute 89 % for percent passing No.4 sieve in Equation (2).

$\begin{array}{c}\text{Gravel}\text{fraction}=100-89\\ =11\text{\%}\end{array}$

Determine the sand fraction using the relation.

Substitute 35 % for percent of coarse fraction 11 % for percent of coarse fraction in Equation (3).

$\begin{array}{c}\text{Sand}\text{fraction}=35-11\\ =24\%\end{array}$

Refer Table 5.2 “Unified soil classification system” in the text book.

The soil is a fine-grained soil.

Refer Table 5.2 “Unified soil classification system” and Figure 5.3 “Plasticity chart” in the text book.

The group symbol of the soil can be taken as $\underset{\_}{\text{CL}}$.

Provide the group name of soil as shown below.

Refer Figure 5.5 “Flowchart group names for inorganic silty and clayey soil” in the text book.

Take the group name as sandy lean clay for the group of CL, $\ge 30\%$ plus No.200, $\%\text{sand}\ge \%\text{gravel}$, and $<15\%\text{gravel}$.

Thus, the classification of soil 11 using unified soil classification system is $\underset{\_}{\text{Sandy}\text{lean clay}}$.

For soil 12:

The plasticity index (PI) is 31.

Determine the coarse fraction as shown below.

Substitute 8 % for percent retained on No.200 sieve in Equation (1).

$\begin{array}{c}\text{Coarse}\text{fraction}=100-8\\ =92\text{\%}\end{array}$

Determine the gravel fraction as shown below.

Substitute 90 % for percent passing No.4 sieve in Equation (2).

$\begin{array}{c}\text{Gravel}\text{fraction}=100-90\\ =10\text{\%}\end{array}$

Determine the sand fraction using the relation.

Substitute 92 % for percent of coarse fraction 10 % for percent of coarse fraction in Equation (3).

$\begin{array}{c}\text{Sand}\text{fraction}=92-10\\ =82\%\end{array}$

Refer Table 5.2 “Unified soil classification system” and Figure 5.3 “Plasticity chart” in the text book.

The group symbol of the soil can be taken as $\underset{\_}{\text{SP-SC}}$.

Provide the group name of soil as shown below.

Refer Figure 5.4 “Flowchart group names for gravelly and sandy soil” in the text book.

Take the group name as poorly graded sand with clay for the group of SP-SC and gravel fraction of $<15\%$.

Thus, the classification of soil 12 using unified soil classification system is $\underset{\_}{\text{Poorly graded}\text{sand with clay}}$.