3. The Plasticity Index (PI) and the Liquid Limit (LL) are soil properties used
ID: 2247061 • Letter: 3
Question
3. The Plasticity Index (PI) and the Liquid Limit (LL) are soil properties used in the AASHTO soil classification system. Figure 15.3 below shows how depending on the PI and LL values, soils could fall into different categories. For example: a. for PI = 50 and LL = 50, the soil would be classified as A-7-6 b. for PI = 5 and LL = 50, the soil would be classified as A-5 or A-2-5 (where two categories are listed the soil could be either one, so include both) c. … and so on, depending on the area where a point of coordinates LL, PI lands
Using visual basic (VBA) develop an application where users can enter values for PI and LL and the application will automatically find the AASHTO soil category as described in Figure 15.3. If the point is exactly on a border line between different areas it is ok if only one of the areas is identified and it does not matter which one. The program should work for any possible combination of LL and PI values. Submit this application online in the Homework and Exam folder. Don’t forget to sign it and make it unique.
Explanation / Answer
finecontent= input('Enter the percentage of soil passing US sieve No.200 (0.074 mm):');
percentage=100-finecontent;
if percentage>50
Sieve_result =input('Please enter the data obtained at the end of sieve analysis in the matrix form. The first column represents the sieve mesh (in mm) and the second column represents the mass retained on the Sieve (in g). Please do not forget to take the soil remained on the pan.Enter sieve mesh value for the pan as 0.0 e.g. Sieve_result = [4.76 0.0;3.36 180.0;2.38 125.0;2.0 75.0;1.19 60.0;0.84 35.0;0.42 25.0;0.0 50.0] ');
sieve_size= Sieve_result(:,1);
mass_retained=Sieve_result(:,2);
no= length(sieve_size);
for i = 1 : no
if sieve_size(i,1) <75 && sieve_size(i,1) >= 4.75
gravel(i,1) = mass_retained(i);
end
end
Gravel=sum(gravel(:,1));
for i = 1 : no
if sieve_size(i,1) <4.75 && sieve_size(i,1) >= 0.075
sand(i,1) = mass_retained(i);
end
end
Sand=sum(sand(:,1));
for i=2:no
mass_retained(i)= mass_retained(i)+mass_retained(i-1);
end
tot_mass=mass_retained(no);
percent_gravel=(Gravel/tot_mass)*100
percent_sand= (Sand/tot_mass)*100
for i=1:no
percent_cum_ret(i)= (mass_retained(i)/mass_retained(no))*100;
end
for i=1:no
percent_cum_passing(i)=100-percent_cum_ret(i);
end
result=percent_cum_passing';
[result, index] = unique(result);
D10 = interp1(result, sieve_size(index), 10, 'pchip')
D30 = interp1(result, sieve_size(index), 30, 'pchip')
D60 = interp1(result, sieve_size(index), 60, 'pchip')
result;
sieve_size=sieve_size(index);
Cu=D60/D10
Cc=(D30^2)/(D10*D60)
figure;
CCurve_h = semilogx(sieve_size,result,'Linewidth' , 2.0, 'Color' , [1 0 1] );
title('Grain Size Distribution ' , 'Color' , [1 0.5 0] )
xlabel('Particle Size (mm)', 'Fontsize' , 9);
ylabel('Percentage Finer by Weight ' , 'Fontsize' , 9);
set(gca, 'Xgrid' , 'on' , 'Ygrid' , 'on' , 'Xcolor' , [0 0 0.37] , 'Ycolor' , [0 0 0.37] , 'Box' , 'off' , 'XDir' , 'normal' , ...
'FontWeight' , 'Bold' , 'FontSize' , 7 , 'FontAngle' , 'Oblique' , 'XMinorTick' , 'on' , 'YMinorTick' , 'on', ...
'Xlim' , [0.01 10] ,'Ylim', [0 100],'XTickLabel', { '0.01' ; '0.1' ; '1' ; '10' } );
if percentage>50 & Gravel>Sand & finecontent>12
LL=input('What is the liquid limit:');
PL=input('What is the plastic limit:');
PI=LL-PL;
end
end
if percentage>50 & Gravel>Sand & (0<=finecontent && finecontent<=5) & Cu>4 & ( 1<Cc && Cc<3)
sprintf('Soil classification based on USCS is: GW (well-graded gravel)')
elseif percentage>50 & Gravel>Sand & (0<=finecontent && finecontent<=5 ) & Cu<=4 & (Cc<1 | Cc>3)
sprintf('Soil classification based on USCS is: GP (poorly graded gravel)')
elseif percentage>50 & Gravel>Sand & finecontent>12 & (PI<0.73*(LL-20) | PI<4)
sprintf('Soil classification based on USCS is: GM (silty gravel)')
elseif percentage>50 & Gravel>Sand & finecontent>12 & (PI> 0.73*(LL-20) &PI>7)
sprintf('Soil classification based on USCS is: GC (clayey gravel)')
elseif percentage>50 & Gravel>Sand & finecontent>=12 & LL<50 & (4<PI && PI<7)& PI> (0.73*(LL-20))
sprintf('Soil classification based on USCS is: GC-GM ( silty,clayey gravel)')
end
if percentage>50 & Gravel>Sand & (5<finecontent & finecontent<12)
LL=input('What is the liquid limit:');
PL=input('What is the plastic limit:');
PI=LL-PL;
if Cu>4 & (1<Cc & Cc<3) & (PI<0.73*(LL-20) | PI<4)
sprintf('Soil classification based on USCS is: GW-GM (well graded gravel with silt)')
elseif Cu>4 & (1<Cc & Cc<3) & (PI> 0.73*(LL-20)) &PI>4
sprintf('Soil classification based on USCS is: GW-GC (well graded gravel with clay)')
elseif Cu<=4 & (Cc<1 | Cc>3) & (PI<0.73*(LL-20) | PI<4)
sprintf('Soil classification based on USCS is: GP-GM(poorly graded gravel with silt)')
elseif Cu<=4 & (Cc<1 | Cc>3) & PI> 0.73*(LL-20) &PI>7
sprintf ('Soil classification based on USCS is: GP-GC(poorly graded gravel with clay)')
end
end
if percentage>50 & Sand>Gravel & finecontent>12
LL=input('What is the liquid limit:');
PL=input('What is the plastic limit:');
PI=LL-PL;
end
if percentage>50 & Sand>Gravel & (5<finecontent & finecontent<12)
LL=input('What is the liquid limit:');
PL=input('What is the plastic limit:');
PI= LL-PL;
if Cu>6 & (1<Cc & Cc<3) & (PI<0.73*(LL-20) | PI<4)
sprintf('Soil classification based on USCS is: SW-SM(well graded sand with silt)')
elseif Cu>6 & (1<Cc & Cc<3) & (PI> 0.73*(LL-20)) &PI>4
sprintf('Soil classification based on USCS is: SW-SC(well graded sand with clay)')
elseif (Cu<=6 | (Cc<1 | Cc>3))& (PI<0.73*(LL-20) | PI<4)
sprintf('Soil classification based on USCS is: SP-SM(poorly graded sand with silt) ')
elseif (Cu<=6 | Cc<1 | Cc>3)& (PI> 0.73*(LL-20)) &PI>4
sprintf('Soil classification based on USCS is: SP-SC(poorly graded sand with clay)')
end
end
if percentage>50 & Sand>Gravel & (0<finecontent && finecontent<5) & Cu>6 & (1<Cc && Cc<3)
sprintf('Soil classification based on USCS is: SW (well graded sand)')
elseif percentage>50 & Sand>Gravel & (0<finecontent && finecontent<5)& (Cu<=6 | Cc<1 | Cc>3)
sprintf('Soil classification based on USCS is: SP (poorly graded sand)')
else if percentage>50 & Sand>Gravel & finecontent>12 &( PI< 0.73*(LL-20) | PI<4)
sprintf('Soil classification based on USCS is: SM (silty sand)')
elseif percentage>50 & Sand>Gravel & finecontent>12 &( PI> 0.73*(LL-20) & PI>7)
sprintf('Soil classification based on USCS is: SC (clayey sand)')
elseif percentage>50 & Sand>Gravel & finecontent>12 & (4<PI && PI<7)& PI> (0.73*(LL-20))
sprintf('Soil classification based on USCS is: SC-SM (silty-clayey sand)')
end
end
if (percentage<50)
LL=input('What is the liquid limit:');
PL=input('What is the plastic limit:');
PI=LL-PL;
end
if (percentage<50) & LL<50 & PI>7 & PI> (0.73*(LL-20))
sprintf('Soil classification based on USCS is: CL (clay of low plasticity)')
elseif ( percentage<50 & LL<50 & (PI<4 & PI> (0.73*(LL-20)))) | (percentage<50 & LL<50 & PI<0.73*(LL-20))
sprintf('Soil classification based on USCS is: ML (silt)')
elseif (percentage<50) & LL<50 & (4<PI && PI<7)& PI> (0.73*(LL-20))
sprintf('Soil classification based on USCS is: CL-ML(silty clay) ')
elseif (percentage<50) & LL>=50 & (PI>=0.73*(LL-20))
sprintf('Soil classification based on USCS is: CH (clay of high plasticity)')
elseif (percentage<50)& LL>50 & PI< 0.73*(LL-20)
sprintf('Soil classification based on USCS is: MH (silt of high plasticity)')
end
Equation for U – line:Ip= 0.9( 8)
For a soil specimen, given:
Passing 2 mm sieve = 100 %; Passing 0.425 mm sieve = 85 %;
Passing No. 200 sieve = 38 %
LL = 20 % and PI = 12 %
Classify the soil by the Unified soil classification system
For a soil specimen, given:
Passing No. 4 sieve = 92 %; Passing No. 40 sieve = 78 %;
Passing No. 10 sieve = 81 %; Passing No. 200 sieve = 65 %
LL = 48 % and PI = 32 %
Classify the soil by the unified classification system
No. 4 sieve = 4.75 mm
No. 10 sieve = 2 mm;
No. 40 sieve = 0.425 mm sieve
For soil A, G = 2%, S = 98%;
M = 0% & C = 0%.
CU = 1.4/0.5 = 2.8; Cc = 0.952/(1.4)*(0.5) = 1.29
Soil A is a poorly graded sand (SP)
For soil B, G = 0%, S = 61%;
M = 35% & C = 4%.
CU = 0.45/0.005 = 90
Soil A is a very well graded silty sand (SM)
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.