Shrinkage Limit & Particle Size Distribution Curve - GATE Civil Soil Mechanics

The equipment for determination of shrinkage limit consist of Porcelain evaporating dish, two glass plates, stainless steel shrinking dish.

A soil is said to be well graded when it has a good representation of particle of all size.

Vaseline prevents the formation of air-bubbles. Hence it is used as for inner coating in a shrinking dish.

The coefficient of curvature (Cc) is given by the equation Cc = (D30)2/D10×D60.

The right side the particle size distribution curve shows the coarse-grained while the left shows the relatively fine-grained soil.

Mixing the soil with sufficient distilled water and making it pasty enough prevents forming air bubbles in shrinking dish.

A curve with a flat portion represents oil in which intermediate size particle are missing.

Since VS = (VL-Vd) × 100/Vd
But, (VL-Vd)×100/Vd = (WL-WS) SR
Therefore, VS = (WL-WS) SR.

γ = 0.905(0.01)
γ = 9.05 × 10^-5
t = 15hr 20min 49sec = 55429 sec
t = h/v
55429 = h/9.05 × 10^-5
h = 55429 × 9.05 × 10^-5
h = 5.000034 m.

Alternatively, shrinking limit can be found out if the specific gravity G of the soil grains is known.

A particle-size curve shows both type and gradation of the soil.

The density of mercury = 13.6 g/cm³.

The size D10 is sometimes called as the effective size or effective diameter.

One –third of shrinkage dish is filled with wet soil to prevent overflow.

The coefficient of uniformity CV, is defined as the ratio of D60 and D10
i.e.CV = D60/ D10.