Non-clay v.s. Clay SoilsMajor Contents

- Composition of a given soil

- Properties of non-clay soils

- Properties of clay soils

- Soil classification

- Gradations of soil

- SPT v.s. MPT

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Non-clay v.s. Clay SoilsI. *Components of a given soil1. Solids (mineral: inorganic and/or organic)2. Water and /or3. Air II.* Phases of soil1. Dry soil: void space contains only air. 2. Saturated soil(fully saturated & partially saturated ):

soil whose void space contains only water. ( semi-saturated).

3. Submerged III. *Properties of Non-clay (granular) soils1. Constituents: predominantly of gravel, sand, and silt

y particles2. Frictional forces between the contact plane among p

articles: keeping the particles from sliding past one another

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Non-clay v.s. Clay Soils3. Function of water: to keep an unconfined vertical

surface steep; some water may increase the potential for the surface to approach vertical.

4. Magnitude of the surface tension:

1) Keeping hold of the particles together (among air, water and particles)

2) The greatness of the surface tension increases as the size of the pore space decreases

3) Relatively small in gravelly soil, while considerably large in clayey soil

4) Greater the surface tension is, more slowly the surface of a soil dries.

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Non-clay v.s. Clay Soils

IV. *Properties of Clay Soils1. Shape: Flat and platy due to their molecular structur

e and thus providing a broad surface for electro-chemical interaction

2. Overall electrical charge: the platy shape and electrical charge prolong contact with water and /or air

3. Very low permeabilityIV. *Soil Classification 1. Principles for Soil Classification1) on the basis of a scientific method 2) simple 3) permitting classification by visual and manual tests. 4) describing certain engineering properties 5) acceptable to all engineers 4 Thursday, April 20, 2023

Non-clay v.s. Clay Soils

2. *USCS (Unified Soil Classification System)

1) Development

2) Basis of the USCS:

(1) Sizes of the particles

(2) Soil’s plasticity

(3) By percentage (weight) of different sized particles by sieving a representative sample of the soil through screen openings of various sizes

V. Gradations of a Soil

1. Definition: Distribution of particle sizes within a given sample

2. Poorly-graded

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Non-clay v.s. Clay SoilsV. Gradations of a Soil

3. Well-graded: having no excessive amounts of one size particles and no gaps in another size of particles

VI. Organic Soil

1. Identified on the basis of the presence of any organic materials and its plasticity rather than on any specific particle size

2. Disadvantages of organic soils in foundation

VII. *SPT (Standard Penetration Test) v.s. MPT (Modified Penetration Test)

1. Only suitable for sand, gravel, clay and the like.

2. The hammer of SPT is lighter than that of MPT, which would be the only significant difference of the two.

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Components of Soil

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Soil Phases

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