Q$4$: $8(5$ marks$)$

a$.$ Write down at least $4$ differences between AASHTO and Unified soil classification systems?

b$.$ Given the following properties and sieve analysis. The liquid limit $($L$)=23\%,$ and plastic limit $(PL)=19.$ Classify the soil according to the AASHTO system, give group name and group index.

$\backslash$table$[[$Sieve #$,\%$ Passing$],[4,100],[10,90],[40,38],[200,13]]$