1. Chapter 1: Engineering Properties of Soils
What is the definition of soils?

2. Soils = All Material Above Bedrock
Included in soils are gravel, sand , clay, organic material, air, and water.
Mineral soil was formed by weathering of the planets bedrock
Physical Weathering - The process of freeze/thaw, water, landslides, glaciers, and animal /plant life which break bedrock into granular soils.

3. Chemical Weathering
Chemical weathering - Water runs through rocks leaching out some of the minerals. The resulting material are called clays.
Main Type of Mineral Soils
Gravel
Sand
Silt
Clay

4. Gravel / Sands vs. Clays
Gravel / Sands - Grains are cubical or rounded providing the ability to carry heavy loads. The load is transferred by friction among the grains.
Clays - Cannot carry loads like Gravel/Sand. Surplus negative charges on the clay particle attracts moisture. Ratios up to 40:1 (Water:Soil)

5. Mass - Volume Relations
Soil Phase Model
Total Volume = Volume/Air Volume/Water +
Volume/Soils
Total Mass = Mass/Water +
Mass/Soils
Air
Water
Solids

6. Mass - Volume Relations, cont.
Density = Mass / Volume
Dry Density = Dry Mass / Volume
Water Content = Mass of Water / Dry Mass
Void Ratio = (Vol.of Air +Vol.of Water) /
(Vol.of Soils
Degree of Saturation = Vol. of Water /
Total Volume
Porosity = (Vol.of Air + Vol.of Water) /

7. Classification Tests ASTM D 422-63 Particle-Size Analysis of Soils
Types
Grain size measure
Sieve Analysis For Sands and Gravels
Hydrometer For Clays and Silts

8. Sieve Analysis
Sieve Analysis is the process of shaking the dry material through a series of screens. The screen openings decrease in size down the stack. Weighing the weight of material retained on each screen provides the data to classify the soil. Standard screen sizes: #4,#10, #20, and # 200 indicate the number of openings per square inch.

9. Hydrometer Test
Clay and silt particles are too small for the eye to see
The particles are suspended in water
Particles suspended settle at a rate according to their size
Hydrometer is used to measure the density at different times while the grains settle

10. Liquid Limit, Plastic Limit, and Plasticity Index of Soils
ASTM D a
Liquid Limit, Plastic Limit, and Plasticity Index of Soils
Known as the Atterberg Limits Test
Material is sieved through the #40 screen
Plastic Limit
Water is added until the soil can be rolled to ⅛” diameter thread and starts to crumble
This moisture content becomes the Plastic Limit

11. ASTM D 4318 -95a Liquid Limit, Plastic Limit, and Plasticity Index of Soils
Soil is placed in a brass cup
Grove is run through soil
Turning the crank of the brass cup raises and drops the cup
Moisture content when it takes 25 drops to close grove = Liquid limit

12. Liquid Limit, Plastic Limit, and Plasticity Index of Soils Formula
ASTM D a
Liquid Limit, Plastic Limit, and Plasticity Index of Soils Formula
Liquid Limit - Plastic Limit = Index of Plasticity

13. Soils Classification United Soils Classification System
Unified Soil Classification System - Wikipedia, the free
Uses a combination of Sieve Analysis and Atterberg Limits Test to classify soils

14. AASHTO T 215 Permeability of Granular Soil
Tests the flow rate of water through material

15. Shear Strength In Soils
Unconfined Compression Test
Direct Shear Test
Triaxial Compression Test

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