1. SOILS PRESENTATION ACPA PIPE CLASS By: Colin A. Franco, P.E.
Associate Chief Engineer
RIDOT
Orlando, Florida
March 3, 2015

2. Soils - Definition
Soil is the entire unconsolidated earthen material that overlies and excludes bedrock.
It is composed of loosely-bound mineral grains of various sizes and shapes.
Due to its nature of being loosely bound, it contains many voids of varying sizes.
These voids may contain air, water, organic matter, or different combinations of these materials.

3. Soils – Formation From Rock
Soil forms when rocks that are exposed to the atmosphere disintegrate and decompose, either by mechanical action (wind, water, ice, and vegetation), chemical action, or both.
The resulting material may remain where it is formed or it may be transported by water, glaciers, wind, or gravity and deposited at a distance from the parent rock.
Geologists classify rocks into three basic groups:
Igneous (formed by cooling from a molten state).
Sedimentary (formed by the accumulation and cementation of existing particles and remains of plants and animals).
Metamorphic (formed from existing rocks subjected to heat and pressure).

4. Soils - Sampling
Test Pit

5. Solis - Sampling
Soil Auger

6. Soils - Sampling
Boring
Boring Log

7. Soils – Sampling (Field)
Quartering

8. Soils – Sampling (Lab)
Splitting

9. Soil - Types Granular Soils  Sands and Gravel
Fine-grained Soils  Silts and Clays
Organic Soils  Peat, Organic clays and silts

10. Soils – Granular Soils Coarse-grained
Gravel, sand, & fine-grained soil- Separately or combined
>50% retained on the #200 sieve.
“Well Graded”
A good representation of all particle sizes
“Poorly graded”
Uniformly graded
Most particles about the same size or lacking one or more intermediate sizes.
“Gap graded”
One or more grain sizes are missing.

11. Soils – Granular Soils (Cohesionless)

12. Soils – Fine-Grained Soils
Fine-grained soils are those in which 50 percent or more pass the No. 200 sieve (fines) and the fines are inorganic or organic silts and clays.

13. Soils – Organic Soils Organic Soils
Soils that contain significant amounts of muck. (Example: Organic Silt)
Muck
Deposits of a saturated or unsaturated mixture of soils and organic matter not suitable for foundation material regardless of moisture content.
Organic Matter
The more or less decomposed material of soil derived from organic sources, usually from plant remains. The term "organic matter" covers such material in all stages of decay. (Example: Peat)

14. Soils – Physical Properties
A soil’s physical properties help determine the engineering characteristics. The following properties are the basis for the soil-classification system used in engineering identification of soil types. The discussion of the physical properties of soil focuses on the soil particles themselves. The terms particle and grain are used interchangeably.
Grain size.
Particle shape.
Sieve Analysis.
Density.
Specific gravity.
Moisture.
Consistency.
Organic soil.
Plasticity characteristics of fine-grained soil components include the liquid limit (LL) and the plastic limit (PL).

15. Soils – Grain Size
< ¼”
< ¼”

16. Soils – Aggregate Shapes
Cubical
Flat
Irregular
Elongated
Rounded

17. Soils - Gradation
Sieve Analysis

18. Distribution of Grain Size
Soils - Gradation
Distribution of Grain Size
Poor
Well
Gap

19. Soils - Gradation
Grain Size Plot

20. Soils – Lab Test Plasticity
Plasticity is a soil’s ability to deform without cracking or breaking.
A plasticity index (PI) is used to determine whether soil is cohesive.
Soil is considered cohesive if its PI is greater than 5.
Gravels, sands, and most silts are not cohesive and are called cohesionless soils.
In engineering practice, soil plasticity is determined by observing the different physical states that a plastic soil passes through as the moisture conditions change.

21. Plastic Limit (PL) Test
Soils – Lab Test
Plasticity
Plasticity Index (PI)
PI = LL-PL
Liquid Limit (LL) Test
Plastic Limit (PL) Test
1 8 ”

22. Soils – Classification
Plasticity Chart

23. Soils - Classification
USCS Classification

24. Soils - Classification
AASHTO Classification

25. Soils – Tests for Construction
Moisture Content - AASHTO T225

26. Soils – Tests for Construction
Compaction Test - AASHTO T180
Hammer - 10 LBS
Drop – 18”
Layers - 5

27. Soils – Tests for Construction
Compaction Plot
Discussion:
Compaction is Important
Improves shear strength of a soil.
Loose soils under “saturated conditions” can become “quick” or unstable.
Adds support and provides strength to buried structures.
Reduces subsidence or settlements of supporting structures.

28. Soils – Tests for Construction
CBR - AASHTO T193

29. Soils – Field Testing Visual Examination Roll/Thread Test
Separate Gravel
Wet Shaking Test
Odor Test
Breaking/Dry-Strength Test
Sedimentation Test
Ribbon Test
Bite/Grit Test
Shine Test
Feel Test