SoilClass_ATT&USCS_Lecture 3(2)

Plasticity index, I p Liquid limit, w l (%) Plasticity index, I p Liquid limit, w l (%) Atterberg’s Limits ( A -Line Chart) 0 10 20 30 40 50 60 70 80 90 100 0.001 0.01 0.1 1 10 100 Particle size (mm) % Passing clay cobbles silt sand gravel fine medium coarse fine medium coarse fine medium coarse 0.002 0.075 2.36 63.0 0.006 0.02 0.2 0.6 6.0 20.0 Particle Size Distribution Curve (Sieve Analysis + Hydrometer Test) Sieve Analysis Hydrometer Test Sieve size 0.075 mm Last time… Unified Soil Classification System (USCS) Today…

Liquid Limit (LL or w L ) … the water content over which the soil behaves like a viscous mud, flowing under its own weight and having a very little strength. It is the transitional water content between the plastic state and liquid state.

Liquid Limit by Cone Penetrometer ( https://ecmslin04.services.adelaide.edu.au/OLT ) (Log scale) AS 1289.3.9.1 – Liquid Limit determination (Falling Cone Penetrometer)

Consistency Limits (Plastic Index, Liquidity Index and Activity) Plastic Index ( PI ) PI = 0 ……… (Nonplastic) PI < 7 ……….(Slightly plastic) 7 ≤ PI ≤17 ….(Medium plastic) PI >17 ………(Highly plastic) Soils with a high PI tend to be clay, those with a lower PI tend to be silt, and those with a PI of 0 (non-plastic) tend to have little or no silt or clay. Plastic Index PI = LL - PL Plasticity Index (PI): the range of water content over which the soil remains plastic.

Atterberg’s Limits ( A -Line Chart) H = High plasticity L = Low plasticity O = organic C = clay M = silt

Unified Soil Classification System … …two-letter code for soil classification: Major Soil Group + Descriptor Major soil group Descriptor G ravel ( G ) S and ( S ) W ell-graded ( W ) P oorly-graded ( P ) Silty ( M ) C layey ( C ) S ilt ( M ) C lay ( C ) O rganic ( O ) L ow plasticity ( L ) H igh plasticity ( H ) Peat ( Pt ) N/A GW = W ell-graded GRAVEL GP = P oorly-graded GRAVEL SW = W ell-graded SAND SP = P oorly-graded SAND GM = S ilty GRAVEL GC = C layey GRAVEL SM = S ilty SAND SC = C layey SAND ML = L ow plasticity SILT MH = H igh plasticity SILT CL = L ow plasticity CLAY CH = H igh plasticity CLAY OL = L ow plasticity ORGANIC soil OH = H igh plasticity ORGANIC soil Pt = Peat

Lecture Example  A grain size distribution analysis is carried out on a soil which gave the results shown in the figure below. Atterberg limits were performed on the fine fraction of the soil and gave a liquid limit of 45% and plastic limit of 20%. Classify the soil using the USCS and show all necessary calculations. Assume no organic content) 0 10 20 30 40 50 60 70 80 90 100 0.001 0.01 0.1 1 10 100 % Passing Particle Size (mm)

0 10 20 30 40 50 60 70 80 90 100 0.001 0.01 0.1 1 10 100 % Passing Particle Size (mm) Retained 0.075mm sieve = 100-23 = 77% Retained 2.36 mm sieve = 100 – 92 = 8% Passing 0.075mm sieve = 23% Passing 2.36 mm sieve = 92%

Unified Soil Classification System Criteria for assigning Group Symbols and Group Names using laboratory tests Soil Classification Group Symbol Group Name Coarse Grained Soil (% retained on 0.075 mm sieve > 50%) Gravel (% retained on 2.36 mm sieve > 50%) (%fines < 5%) a C u ≥ 4 and C c = 1–3 c GW Well-graded Gravel C u < 4 or C c ≠ 1 –3 c GP Poorly-graded Gravel (%fines > 12%) a Fines classified as SILT (M) GM Silty Gravel Fines classified as CLAY (C) GC Clayey Gravel Sand (% retained on 2.36 mm sieve < 50%) (%fines < 5%) b C u ≥ 6 and C c = 1–3 c SW Well-graded Sand C u < 6 or C c ≠ 1 –3 c SP Poorly-graded Sand (%fines > 12%) b Fines classified as SILT (M) SM Silty Sand Fines classified as CLAY (C) SC Clayey Sand Fine Grained Soil (% retained on 0.075 mm sieve < 50%) Silts or Clays (Liquid Limit < 50) Inorganic PI plots on or above A- line d CL Low plasticity Clay PI plots below A- line d ML Low plasticity Silt Organic e PI plots on or above A- line d OL Low Plasticity Organic Clay PI plots below A- line d OL Low Plasticity Organic Silt Silts or Clays (Liquid Limit ≥ 50) Inorganic PI plots on or above A- line d CH High Plasticity Clay PI plots below A- line d MH High Plasticity Silt Organic e PI plots on or above A- line d OH High Plasticity Organic Clay PI plots below A- line d OH High Plasticity Organic Silt Highly Organic Soil Primarily organic matter, dark in colour and rotten odour Pt Peat a Gravel with (5–12%) fines requires dual symbols as follows: GW–GM Well-graded Gravel with Silt GW–GC Well-graded Gravel with Clay GP–GM Poorly-graded Gravel with Silt GP–GC Poorly-graded Gravel with Clay b Sand with (5–12%) fines requires dual symbols as follows: SW–SM Well-graded Sand with Silt SW–SC Well-graded Sand with Clay SP–SM Poorly-graded Sand with Silt SP–SC Poorly-graded Sand with Clay c 10 60 D D C u = and 60 10 2 30 ) ( D D D C c × = d CL–ML Atterberg limits plot in the hatched area, soil is classified as Low Plasticity Clay and Silt e The soil has between 20-75% organic matter Plasticity index, I p Liquid limit, w l (%) Plasticity index, I p Liquid limit, w l (%) Liquid limit = 45% and plastic limit = 20%. Retained 0.075mm sieve = 77% Retained 2.36 mm sieve = 8%

Worked Example (3) A grain size distribution analysis is carried out on a soil which gave the results shown in the figure below. Atterberg limits were performed on the fine fraction of the soil and gave a liquid limit of 40% and plastic limit of 34%. Classify the soil using the USCS and describe all the necessary steps for your classification. 0 10 20 30 40 50 60 70 80 90 100 0.001 0.01 0.1 1 10 100 % Passing Particle size (mm) clay cobbles silt sand gravel fine medium coarse fine medium coarse fine medium coarse 0.002 0.075 2.36 63.0 0.006 0.02 0.2 0.6 6.0 20.0

Unified Soil Classification System Criteria for assigning Group Symbols and Group Names using laboratory tests Soil Classification Group Symbol Group Name Coarse Grained Soil (% retained on 0.075 mm sieve > 50%) Gravel (% retained on 2.36 mm sieve > 50%) (%fines < 5%) a C u ≥ 4 and C c = 1–3 c GW Well-graded Gravel C u < 4 or C c ≠ 1 –3 c GP Poorly-graded Gravel (%fines > 12%) a Fines classified as SILT (M) GM Silty Gravel Fines classified as CLAY (C) GC Clayey Gravel Sand (% retained on 2.36 mm sieve < 50%) (%fines < 5%) b C u ≥ 6 and C c = 1–3 c SW Well-graded Sand C u < 6 or C c ≠ 1 –3 c SP Poorly-graded Sand (%fines > 12%) b Fines classified as SILT (M) SM Silty Sand Fines classified as CLAY (C) SC Clayey Sand Fine Grained Soil (% retained on 0.075 mm sieve < 50%) Silts or Clays (Liquid Limit < 50) Inorganic PI plots on or above A- line d CL Low plasticity Clay PI plots below A- line d ML Low plasticity Silt Organic e PI plots on or above A- line d OL Low Plasticity Organic Clay PI plots below A- line d OL Low Plasticity Organic Silt Silts or Clays (Liquid Limit ≥ 50) Inorganic PI plots on or above A- line d CH High Plasticity Clay PI plots below A- line d MH High Plasticity Silt Organic e PI plots on or above A- line d OH High Plasticity Organic Clay PI plots below A- line d OH High Plasticity Organic Silt Highly Organic Soil Primarily organic matter, dark in colour and rotten odour Pt Peat a Gravel with (5–12%) fines requires dual symbols as follows: GW–GM Well-graded Gravel with Silt GW–GC Well-graded Gravel with Clay GP–GM Poorly-graded Gravel with Silt GP–GC Poorly-graded Gravel with Clay b Sand with (5–12%) fines requires dual symbols as follows: SW–SM Well-graded Sand with Silt SW–SC Well-graded Sand with Clay SP–SM Poorly-graded Sand with Silt SP–SC Poorly-graded Sand with Clay c 10 60 D D C u = and 60 10 2 30 ) ( D D D C c × = d CL–ML Atterberg limits plot in the hatched area, soil is classified as Low Plasticity Clay and Silt e The soil has between 20-75% organic matter Plasticity index, I p Liquid limit, w l (%) Plasticity index, I p Liquid limit, w l (%)

0 10 20 30 40 50 60 70 80 90 100 0.001 0.01 0.1 1 10 100 % Passing Particle size (mm) clay cobbles silt sand gravel fine medium coarse fine medium coarse fine medium coarse 0.002 0.075 2.36 63.0 0.006 0.02 0.2 0.6 6.0 20.0

Unified Soil Classification System Criteria for assigning Group Symbols and Group Names using laboratory tests Soil Classification Group Symbol Group Name Coarse Grained Soil (% retained on 0.075 mm sieve > 50%) Gravel (% retained on 2.36 mm sieve > 50%) (%fines < 5%) a C u ≥ 4 and C c = 1–3 c GW Well-graded Gravel C u < 4 or C c ≠ 1 –3 c GP Poorly-graded Gravel (%fines > 12%) a Fines classified as SILT (M) GM Silty Gravel Fines classified as CLAY (C) GC Clayey Gravel Sand (% retained on 2.36 mm sieve < 50%) (%fines < 5%) b C u ≥ 6 and C c = 1–3 c SW Well-graded Sand C u < 6 or C c ≠ 1 –3 c SP Poorly-graded Sand (%fines > 12%) b Fines classified as SILT (M) SM Silty Sand Fines classified as CLAY (C) SC Clayey Sand Fine Grained Soil (% retained on 0.075 mm sieve < 50%) Silts or Clays (Liquid Limit < 50) Inorganic PI plots on or above A- line d CL Low plasticity Clay PI plots below A- line d ML Low plasticity Silt Organic e PI plots on or above A- line d OL Low Plasticity Organic Clay PI plots below A- line d OL Low Plasticity Organic Silt Silts or Clays (Liquid Limit ≥ 50) Inorganic PI plots on or above A- line d CH High Plasticity Clay PI plots below A- line d MH High Plasticity Silt Organic e PI plots on or above A- line d OH High Plasticity Organic Clay PI plots below A- line d OH High Plasticity Organic Silt Highly Organic Soil Primarily organic matter, dark in colour and rotten odour Pt Peat a Gravel with (5–12%) fines requires dual symbols as follows: GW–GM Well-graded Gravel with Silt GW–GC Well-graded Gravel with Clay GP–GM Poorly-graded Gravel with Silt GP–GC Poorly-graded Gravel with Clay b Sand with (5–12%) fines requires dual symbols as follows: SW–SM Well-graded Sand with Silt SW–SC Well-graded Sand with Clay SP–SM Poorly-graded Sand with Silt SP–SC Poorly-graded Sand with Clay c 10 60 D D C u = and 60 10 2 30 ) ( D D D C c × = d CL–ML Atterberg limits plot in the hatched area, soil is classified as Low Plasticity Clay and Silt e The soil has between 20-75% organic matter Plasticity index, I p Liquid limit, w l (%) Plasticity index, I p Liquid limit, w l (%)

0 10 20 30 40 50 60 70 80 90 100 0.001 0.01 0.1 1 10 100 % Passing Particle size (mm) clay cobbles silt sand gravel fine medium coarse fine medium coarse fine medium coarse 0.002 0.075 2.36 63.0 0.006 0.02 0.2 0.6 6.0 20.0

Unified Soil Classification System Criteria for assigning Group Symbols and Group Names using laboratory tests Soil Classification Group Symbol Group Name Coarse Grained Soil (% retained on 0.075 mm sieve > 50%) Gravel (% retained on 2.36 mm sieve > 50%) (%fines < 5%) a C u ≥ 4 and C c = 1–3 c GW Well-graded Gravel C u < 4 or C c ≠ 1 –3 c GP Poorly-graded Gravel (%fines > 12%) a Fines classified as SILT (M) GM Silty Gravel Fines classified as CLAY (C) GC Clayey Gravel Sand (% retained on 2.36 mm sieve < 50%) (%fines < 5%) b C u ≥ 6 and C c = 1–3 c SW Well-graded Sand C u < 6 or C c ≠ 1 –3 c SP Poorly-graded Sand (%fines > 12%) b Fines classified as SILT (M) SM Silty Sand Fines classified as CLAY (C) SC Clayey Sand Fine Grained Soil (% retained on 0.075 mm sieve < 50%) Silts or Clays (Liquid Limit < 50) Inorganic PI plots on or above A- line d CL Low plasticity Clay PI plots below A- line d ML Low plasticity Silt Organic e PI plots on or above A- line d OL Low Plasticity Organic Clay PI plots below A- line d OL Low Plasticity Organic Silt Silts or Clays (Liquid Limit ≥ 50) Inorganic PI plots on or above A- line d CH High Plasticity Clay PI plots below A- line d MH High Plasticity Silt Organic e PI plots on or above A- line d OH High Plasticity Organic Clay PI plots below A- line d OH High Plasticity Organic Silt Highly Organic Soil Primarily organic matter, dark in colour and rotten odour Pt Peat a Gravel with (5–12%) fines requires dual symbols as follows: GW–GM Well-graded Gravel with Silt GW–GC Well-graded Gravel with Clay GP–GM Poorly-graded Gravel with Silt GP–GC Poorly-graded Gravel with Clay b Sand with (5–12%) fines requires dual symbols as follows: SW–SM Well-graded Sand with Silt SW–SC Well-graded Sand with Clay SP–SM Poorly-graded Sand with Silt SP–SC Poorly-graded Sand with Clay c 10 60 D D C u = and 60 10 2 30 ) ( D D D C c × = d CL–ML Atterberg limits plot in the hatched area, soil is classified as Low Plasticity Clay and Silt e The soil has between 20-75% organic matter Plasticity index, I p Liquid limit, w l (%) Plasticity index, I p Liquid limit, w l (%)

0 10 20 30 40 50 60 70 80 90 100 0.001 0.01 0.1 1 10 100 % Passing Particle size (mm) clay cobbles silt sand gravel fine medium coarse fine medium coarse fine medium coarse 0.002 0.075 2.36 63.0 0.006 0.02 0.2 0.6 6.0 20.0

Unified Soil Classification System Criteria for assigning Group Symbols and Group Names using laboratory tests Soil Classification Group Symbol Group Name Coarse Grained Soil (% retained on 0.075 mm sieve > 50%) Gravel (% retained on 2.36 mm sieve > 50%) (%fines < 5%) a C u ≥ 4 and C c = 1–3 c GW Well-graded Gravel C u < 4 or C c ≠ 1 –3 c GP Poorly-graded Gravel (%fines > 12%) a Fines classified as SILT (M) GM Silty Gravel Fines classified as CLAY (C) GC Clayey Gravel Sand (% retained on 2.36 mm sieve < 50%) (%fines < 5%) b C u ≥ 6 and C c = 1–3 c SW Well-graded Sand C u < 6 or C c ≠ 1 –3 c SP Poorly-graded Sand (%fines > 12%) b Fines classified as SILT (M) SM Silty Sand Fines classified as CLAY (C) SC Clayey Sand Fine Grained Soil (% retained on 0.075 mm sieve < 50%) Silts or Clays (Liquid Limit < 50) Inorganic PI plots on or above A- line d CL Low plasticity Clay PI plots below A- line d ML Low plasticity Silt Organic e PI plots on or above A- line d OL Low Plasticity Organic Clay PI plots below A- line d OL Low Plasticity Organic Silt Silts or Clays (Liquid Limit ≥ 50) Inorganic PI plots on or above A- line d CH High Plasticity Clay PI plots below A- line d MH High Plasticity Silt Organic e PI plots on or above A- line d OH High Plasticity Organic Clay PI plots below A- line d OH High Plasticity Organic Silt Highly Organic Soil Primarily organic matter, dark in colour and rotten odour Pt Peat a Gravel with (5–12%) fines requires dual symbols as follows: GW–GM Well-graded Gravel with Silt GW–GC Well-graded Gravel with Clay GP–GM Poorly-graded Gravel with Silt GP–GC Poorly-graded Gravel with Clay b Sand with (5–12%) fines requires dual symbols as follows: SW–SM Well-graded Sand with Silt SW–SC Well-graded Sand with Clay SP–SM Poorly-graded Sand with Silt SP–SC Poorly-graded Sand with Clay c 10 60 D D C u = and 60 10 2 30 ) ( D D D C c × = d CL–ML Atterberg limits plot in the hatched area, soil is classified as Low Plasticity Clay and Silt e The soil has between 20-75% organic matter Plasticity index, I p Liquid limit, w l (%) Plasticity index, I p Liquid limit, w l (%)

0 10 20 30 40 50 60 70 80 90 100 0.001 0.01 0.1 1 10 100 % Passing Particle size (mm) clay cobbles silt sand gravel fine medium coarse fine medium coarse fine medium coarse 0.002 0.075 2.36 63.0 0.006 0.02 0.2 0.6 6.0 20.0 D 30 D 10 D 60 D 60 = 5.5mm; D 30 = 0.3mm; D 10 = 0.075mm 𝐶𝐶 𝑢𝑢 = 𝐷𝐷 60 𝐷𝐷 10 = 5.5 0.075 = 73 > 0.4 𝐶𝐶 𝑐𝑐 = 𝐷𝐷 30 2 𝐷𝐷 60 𝐷𝐷 10 = 0.3 2 0.075 ∗ 5.5 = 0.22 ≠ 1 − 3

Unified Soil Classification System Criteria for assigning Group Symbols and Group Names using laboratory tests Soil Classification Group Symbol Group Name Coarse Grained Soil (% retained on 0.075 mm sieve > 50%) Gravel (% retained on 2.36 mm sieve > 50%) (%fines < 5%) a C u ≥ 4 and C c = 1–3 c GW Well-graded Gravel C u < 4 or C c ≠ 1 –3 c GP Poorly-graded Gravel (%fines > 12%) a Fines classified as SILT (M) GM Silty Gravel Fines classified as CLAY (C) GC Clayey Gravel Sand (% retained on 2.36 mm sieve < 50%) (%fines < 5%) b C u ≥ 6 and C c = 1–3 c SW Well-graded Sand C u < 6 or C c ≠ 1 –3 c SP Poorly-graded Sand (%fines > 12%) b Fines classified as SILT (M) SM Silty Sand Fines classified as CLAY (C) SC Clayey Sand Fine Grained Soil (% retained on 0.075 mm sieve < 50%) Silts or Clays (Liquid Limit < 50) Inorganic PI plots on or above A- line d CL Low plasticity Clay PI plots below A- line d ML Low plasticity Silt Organic e PI plots on or above A- line d OL Low Plasticity Organic Clay PI plots below A- line d OL Low Plasticity Organic Silt Silts or Clays (Liquid Limit ≥ 50) Inorganic PI plots on or above A- line d CH High Plasticity Clay PI plots below A- line d MH High Plasticity Silt Organic e PI plots on or above A- line d OH High Plasticity Organic Clay PI plots below A- line d OH High Plasticity Organic Silt Highly Organic Soil Primarily organic matter, dark in colour and rotten odour Pt Peat a Gravel with (5–12%) fines requires dual symbols as follows: GW–GM Well-graded Gravel with Silt GW–GC Well-graded Gravel with Clay GP–GM Poorly-graded Gravel with Silt GP–GC Poorly-graded Gravel with Clay b Sand with (5–12%) fines requires dual symbols as follows: SW–SM Well-graded Sand with Silt SW–SC Well-graded Sand with Clay SP–SM Poorly-graded Sand with Silt SP–SC Poorly-graded Sand with Clay c 10 60 D D C u = and 60 10 2 30 ) ( D D D C c × = d CL–ML Atterberg limits plot in the hatched area, soil is classified as Low Plasticity Clay and Silt e The soil has between 20-75% organic matter Plasticity index, I p Liquid limit, w l (%) Plasticity index, I p Liquid limit, w l (%) liquid limit of 40% and plastic limit of 34%. (PI = 7%)

Next lecture… • Compaction in soils Tutorial… • Finish Tutorial 2 Labs • Start this week Interactive Learning Module for Geotechnical Engineering ( https://ecmslin04.services.adelaide.edu.au/OLT ) - use FireFox Lab Manual