Faculty of Applied Engineering and Urban Planning Civil Engineering Department Soil Mechanics ECGD3303 Grain Size Analysis Lecture 2 Week 1 1 st Quadester 2007/2008 UP Copyrights 2007

Content Purposes of Grain Size Analysis Sieve Analysis Hydrometer Analysis Particle Distribution Shape of Soil Particles

Purposes of Grain Size Analysis The size distribution is often of critical importance to the way the material performs in use. Concrete StructuresEconomical Filler Examples Roads ConstructionBearing Base AgricultureInfiltration Rate EnvironmentFilters

Grain Size Analysis S 1 < d M 1 % S 3 < d < S 2 M 3 % S 2 < d < S 1 M 2 % d < S 3 M 4 %

Sieve Analysis

Standard Sieves Sieve Opening (mm) Sieve No See text book (table 2.5)

Cohesiveness Soils can also be divided into: cohesive and non-cohesive Non-cohesive means the soil has no shear strength if no confinement. Cohesive soil contains clay minerals and posses plasticity Clay is cohesive and plastic. Sand is non-cohesive and non-plastic.

Hydrometer Analysis Based on the principle of sedimentation of soil grains in water and bouncy principle. Stock’s Law V1V1 V2V2 < Bouncy Force F = V ρ g

Hydrometer Analysis

Questions?! 30:00 min

Percent Finer 76.2 mm 4.75 mm mm Pan 100 % Finer (Passing) 93 % 62 % 0 % Gravel Sand Silt and Clay 100 – 93 = 7% 93 – 62 = 31% 62 – 0 = 62% Gravel Sand Silt and Clay

Example: Sieve Analysis

Log-Scale

Group Work

Particle-Size Distribution Curve

1. Effective Size (D 10 ) 2. Uniformity Coefficient (C u ) 3. Coefficient of Gradation (C z ) 10% FinerHydraulic Conductivity

Particle-Size Distribution Curve 1. Effective Size (D 10 ) 2. Uniformity Coefficient (C u ) 3. Coefficient of Gradation (C z ) 10% FinerHydraulic Conductivity

Particle-Size Distribution Curve Question What is the C u for a soil with only one grain size?

Particle-Size Distribution Curve Uniformity Coefficient (C u ) D Finer Grain size distribution

Particle-Size Distribution Curve Criteria for Well-Graded Soil

Particle-Size Distribution Curve

Questions?! 90:00 min

Hydrometer Analysis Stokes’ Law

Hydrometer Analysis

R L L = – R

1. Temperature (F T ) 2. Meniscus Correction (F m ) 3. Zero Correction (F z ) F T = T Corrections: Hydrometer Analysis

Questions?! 105:00 min

Example: Sieve Analysis

Rounded Angular

Questions?! 120:00 min