Certification Set Exam Questions
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Soil Classification - ANSWER Is the arrangement of different soils with similar
properties into groups reflects soil's physical and mechanical properties
Soil is classified according to characteristic properties such as : - ANSWER -
Cohesion: non-cohesive soils (gravel, sand) & cohesive soils (silt, clay)
- Grain size: coarse-grained soils (sand, gravel) & fine-grained soils (silt, clay)
Particle-Size Analysis Tests : - ANSWER 1. Sieve analysis test
2. Hydrometer test
Sieve No. 4 - ANSWER 4.75 mm
Sieve No. 200 - ANSWER 0.075 mm
Coefficient of Uniformity (Cu) = - ANSWER D60/D10
,Coefficient of Curvature (Cc) = - ANSWER D30^2 / ( D60 * D10 )
Well graded sand : - ANSWER Cu > 6 and Cc = (1-3), otherwise, poorly graded
Well graded gravel : - ANSWER Cu > 4 and Cc = (1-3), otherwise, poorly
graded
Consistency of Cohesive Soil depends on : - ANSWER - Depends on the water
content of the soil.
(At very low water contents, soil sample behaves like a solid )
(At very high water contents, may flow like a liquid)
soil water content, cohesive soil may be divided into 4 basic states : - ANSWER
- solid ( Dry )
- semi-solid ( Shrinkage Limit )
- plastic ( Plastic Limit )
- liquid ( Liquid Limit )
Plasticity Index (PI) - ANSWER PI = LL - PL
Liquid Limit Test (LL) - ANSWER The water content at the soil will just close
(0.5 inch) after 25 drops. ( WL for 25 drops)
Plastic Limit Test (PL) - ANSWER The water content at which soil crumbles
when rolled into threads 3 mm (1/8" in) in diameter.
, Shrinkage Limit Test : - ANSWER The water content of this sample if it is
saturated with water at the same volume
GW - ANSWER well graded gravel without fines (symbol)
GP - ANSWER poorly graded gravel without fines (symbol)
SW - ANSWER well graded sand without fines (symbol)
SP - ANSWER poorly graded sand without fines (symbol)
S - ANSWER sand (symbol)
G - ANSWER gravel (symbol)
M - ANSWER silt (symbol)
C - ANSWER clay (symbol)
O - ANSWER organic silt or clay (symbol)
GM - ANSWER silty-gravels (symbol)
, GC - ANSWER clayey-gravels (symbol)
SM - ANSWER silty sand (symbol)
SC - ANSWER clayey sand (symbol)
ML - ANSWER silt with low plasticity (symbol)
CL - ANSWER clay with low plasticity (symbol)
MH - ANSWER Plastic silts (symbol)
CH - ANSWER clay with high plasticity (symbol)
L - ANSWER liquid limit below 50 (low plasticity) (symbol)
H - ANSWER liquid limit above 50 (high plasticity) (symbol)
OL - ANSWER organic silt-clay of low plasticity (symbol)
OH - ANSWER organic clay of high plasticity (symbol)
PT - ANSWER peat and highly organic soil (symbol)