uestion 3 The natural soils along a proposed highway alignme

uestion #3 The natural soils along a proposed highway alignment have a particle size distribution as described by curve A in the figure below, a liquid limit of 44, a plastic limit of 21, and is inorganic. Determine the AASHTO soil classification and rate its suitability for pavement support. 5 FINES SAND GRAVEL Fine edium [Coarse! Fine Coarse #200 #4 3\" 100 70 60 50 5 40 a 30 F/ B 20 10 0.001 0.01 0.1 10 100 Particle size (mm)

Solution

Read the AASHTO chart.

% Passing 0.075mm =55%, LL=44 i.e. >41

PI = 44-21 = 23 i.e. >11 and

also LL-30 = 44-30 = 14 i.e. <PI,

So the only classification that fits the data of the soil curve is A-7-6 Clayey Soil

Subgrade material rating: Fair to Poor