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Types of Soil• Three categories of soil: cohesionless,

cohesive and organic soils.• Cohesionless soil : the soil particle do not

tend to stick together.• Cohesive soils are characterized by very small

particle size where surface chemical effectspredominant. The particles do tend to sticktogether-the result of water-particleinteraction and attractive force betweenparticles.

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• Gravel and sand can be classified according toparticle size by sieve analysis.

• The common type of cohesive soil is clay,which has particle sizes less than about 0.005mm.

• Clayey soils cannot be separated by sieveanalysis in to size categories because nopractical sieve can be made with openings so

small; instead, particle sizes may be determineby observing settling velocities of the particlein a water mixture.

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Engineering properties soils• Granular soi ls, except for loose sand, generally

possess excellent engineering properties:• Large bearing capacity•

Small settlement• Make outstanding foundation material for

supporting roads and structure.• Make excellent backfill materials for retaining

wall because they are easily compacted andeasily drained, and because they exert smalllateral pressures.

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• Cohesive soi ls (mostly clays, but also silty claysand clay-sand mixtures with clay being

predominant) exhibit generally undesirableengineering properties compared with those ofgranular soils:

•

Lower shear strength.• They can be plastic and compressible, and they

expand when wetted and shrink when dry.•

They develop large lateral pressure and lowpermeability's.• Poor material for retaining wall backfill.

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• Silty soils are on the border between clayeyand sandy soils. They are fine-grained like

clays but cohesionless like sand.• Silty soils possess undesirable engineering

properties :• High capillarity and susceptibility to frost

action, yet they have low permeability andlow densities.

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• Any soils containing a sufficient amount oforganic matter to affect its engineering

properties is called organic soils .• Organic soils are typically spongy, crumbly,

and compressible. They posses low shear

strength and may contain harmful materials.• Organic soils are essentially unacceptable for

supporting foundation.

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MACKINTOSH PROBE

• Proba Mackintosh atau proba JKR adalah satukaedah yang telah diperkenalkan untukpenyiasatan tanah di peringkat awal. Ianyaadalah satu kaedah yang paling murah dansering diguna pakai untuk tujuan penyiasatantapak.

• Penentuan keupayang galas tanah(bearingcapacity of soils)

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Rajah 1: Susunan umum proba JKR (a), penunjuk proba JKR(b) dan penunjuk proba mackintosh (c).

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Standard Penetration test(ASTM D 1586)

• Useful in determining certain properties of soils,particularly of cohesionless soils, for whichundisturbed sample are not easily obtained.

• 623-N hammer falling 762 mm is used to drivethe split-spoon sampler 457 mm into the soil.

• As a sample is driven the 457 mm into the soil,

the number of blow required to penetrate eachof the three 152-mm increments is recordedseparately.

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• The SPT resistance value (or N-value) isnumber of blow required to penetrate the last

305 mm.• Thus, the N-value represent the number of

blow per foot(305mm).

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Method to correct-N-value

First Method (Peck et al, 1974)

Second Method Terzaghi et al, 1996 and Liao and Whitman

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TYPICAL BORE LOG FOR A PROJECT IN

MALAYSIA

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END