Problem $1$: Soil from a construction site has these laboratory test results: $LL=30\%,PL=18\%,$ Passing No$.200$ sieve $=45\%.$ Classify the soil using the AASHTO Classification System, include the Group Index $($GI$)$ as appropriate, and identify its subgrade rating.

Table $5\mathrm{.}1$ Classification of Highway Subgrade Materials

ENCE $3340$

Homework No$.3$

Name:

Due Date: March $25,2024$

Silt$-$clay materials

General classification

$($more than $35\%$ of total sample passing No$.200)$

A$-7$

Group classification

A$-4$

A$-5$

A$-6$

A$-7-5$

Sieve analysis $($percentage passing$)$

A $-7-6^b$

No$.10$

No$.40$

No$.200$

Characteristics of fraction passing No$.40$

Liquid limit

Plasticity index

Usual types of significant constituent materials

$40$max. $,41$min.

$10$ max.

$10$ max.

Silty soils

$36$min.

$36$min.

$36$min.

General subgrade rating

$40$ max.

$41$min.

$11$min.

$11$min.

Clayey soils

$-$For A$-7-5,\frac{?}{PI}LL-30$

${?}^b$ For A$-7-6,\frac{?}{PI}>LL-30$

ENCE $3340$

Homework No$.3$

Due Date: March $25,2024$

Name:

Fair to poor