We all know that both the liquid and plastic limits are percentages, and the subtraction between LL and PL is the result of what we know as plasticity index (PI).
My question is, the correct way of expressing this plasticity index (PI), do you think it is by adding the percentage?.
LL =30%, PL = 12%, PI = 18%.
OR do you think without the percentage (PI = 18) is ok?.
I asked you this because I noticed many geotech books use different terminologies. There are some which only include them using the LL and PL, but not for the PI. There are other few which do include percentages as units for LL, LP and PI. And there are others which do not use the percentage symbol at all.