HomeMy WebLinkAboutSKYWAY DRIVE ROAD WIDENING - Filed SEPD-SURFACE EXPLORATION/PAVEMENT DESIGN REPORT - 2018-03-074396 GREENFIELD DRIVE
WINDSOR, COLORADO 80550
(970) 545-3908 FAX (970) 663-0282
November 21, 2017
GYS General Contracting, LLC
791 Copper Center Parkway
Colorado Springs, Colorado 80921
Attn: Mr. Brandon Grebe (brandon@growyourstorage.com)
Re: Subsurface Exploration / Pavement Design Report
Skyway Drive Road Widening
Fort Collins, Colorado
EEC Project No. 1172005
Mr. Grebe:
Earth Engineering Consultants, LLC (EEC) personnel have completed the geotechnical
subsurface exploration and pavement design for the Skyway Drive pavement improvements
planned as part of the planned Grow Your Storage facility off-site improvements in Fort Collins,
Colorado. Results of the geotechnical exploration and recommendations concerning subgrade
preparation and pavement sections for use on the pavement improvement areas are provided with
this report.
The roadway improvements planned for construction consist of the widening of a portion of
Skyway Drive in front of the planned self-storage facility. Acceleration/Deceleration lanes for
the self-storage facility are being constructed on the south side of Skyway Drive.
To develop subsurface information in the area of the proposed improvements, EEC personnel
completed two (2) test borings in the pavement improvement area. The test borings were
extended to depths of approximately 10 feet below existing grades. A diagram indicating the
approximate boring locations is included with this report.
Samples of the subsurface materials encountered in the test borings were obtained using split
barrel and California barrel sampling procedures. Laboratory testing of the recovered samples
included moisture content tests on each of the samples and estimation of the unconfined strength
of appropriate samples using a calibrated hand penetrometer. Atterberg limits and washed sieve
Earth Engineering Consultants, LLC
EEC Project No. 1172005
November 21, 2017
Page 2
analysis tests were completed on a selected sample to evaluate the quantity and plasticity of the
fines in the subgrade soils. Swell/consolidation tests were completed on near surface samples to
evaluate the soils tendency to change volume with variation in moisture content and load. A
composite sample was obtained from the test borings for Hveem Stabilometer/R-Value (ASTM
Specification D2844) testing analyses to determine the in-situ subgrade strength characteristics.
Results of the outlined tests are indicated on the attached boring logs and summary sheets.
As a part of the testing program, all samples were examined in the laboratory and classified in
general accordance with the attached General Notes and the Unified Soil Classification System,
based on the soil's texture and plasticity. The estimated group symbol for the Unified Soil
Classification System is indicated on the boring logs and a brief description of that classification
system is included with this report.
Based on results of the field boring and laboratory testing, subsurface conditions can be
generalized as follows. The existing Skyway Drive pavement sections observed in the test
borings included approximately 5 to 6 inches of hot bituminous pavement, over approximately 5
to 6 inches of aggregate base. The in-place subgrade soils consisted of near surface sandy lean
clay transitioning into siltstone/sandstone bedrock at a depth of approximately 5 feet in boring P-
1 and extending to the depths explored at approximately 10 feet below ground surface in boring
P-2. The swell tests completed on the cohesive lean clay soils showed low swell potential at in-
situ moisture and density.
Observations were made while drilling and after completion of the borings to detect the presence
and depth to hydrostatic groundwater. Free water was not observed in the either of the test
borings at the time of drilling. The borings were backfilled immediately after completion of
sampling and longer-term water level observations were not available. Fluctuations in
groundwater levels can occur over time depending on variations in hydrologic conditions and
other conditions not apparent at the time of this report. Perched/trapped water can be
encountered in more permeable zones interbedded with low permeability clays. The location and
amount of perched water can vary over time depending on variations in hydrologic conditions
and other conditions not apparent at the time of this report.
Earth Engineering Consultants, LLC
EEC Project No. 1172005
November 21, 2017
Page 3
ANALYSIS AND RECOMMENDATIONS
Swell – Consolidation Test Results
The swell-consolidation test is performed to evaluate the swell or collapse potential of soils to
assist in determining pavement design criteria. In this test, relatively undisturbed samples obtained
directly from the California ring barrel sampling device are placed in a laboratory apparatus and
inundated with water under a predetermined load. The swell-index is the resulting amount of swell
or collapse expressed as a percent of the sample’s initial thickness, after the inundation period.
Samples obtained at the 1 or 2-foot intervals are generally pre-loaded and inundated with water at
an approximate 150 pounds per square foot (psf) increment to simulate the pavement loading
conditions in general accordance with Larimer County Urban Area Street Standards (LCUASS)
Pavement Design criteria. After the inundation period additional incremental loads are applied to
evaluate consolidation response.
For this assessment, we conducted a total of two (2) swell-consolidation tests on subgrade
samples collected during our subsurface exploration at depths of approximately 2-feet below
existing site grades. The swell index value for the soil samples tested at the 150-psf inundation
pressure revealed low swell characteristics on the order of (+) 0.3% to (+) 1.3. The sandy lean
clay soils also exhibited slightly compressible characteristics.
The swell-index result for the roadway subsoils analyzed herein revealed a swell-index value less
than the LCUASS 2% criteria for requiring a swell-mitigation plan; therefore, swell-mitigation is
not expected for the site.
Subgrade preparation of the proposed Skyway Drive widening section should be completed in
general accordance with the recommendations presented in the LCUASS Pavement Design
Manual – Chapter 22.
Hveem Stabilometer (R-Value)
A composite sample of subgrade materials from the upper 5-feet below pavement grades was
obtained from the test borings, for laboratory Hveem Stabilometer/R-Value, (ASTM Specification
Earth Engineering Consultants, LLC
EEC Project No. 1172005
November 21, 2017
Page 4
D2844) analyses to determine the subgrade strength characteristics of existing subgrade materials.
A summary of the test results is provided below in Table I.
Table I - Summary of Laboratory (R-Value) Characteristics and Classification of Subgrade Soils
Boring Nos. Depth, Ft.
Hveem
Stabilometer
R-Value
ATTERBERG LIMITS AND CLASSIFICATION
LIQUID
LIMIT
PLASTIC
INDEX
% (-) NO. 200
SIEVE
SOIL DESCRIPTION
P-1 & P-2 0.0 – 5.0 14 33 20 55.6 Sandy Lean Clay (CL)
Based on the test results, an R-Value of 14 has been chosen for the pavement design.
Subgrade Preparation
All existing vegetation and any improvements including curb-and-gutter, sidewalk, existing
pavements and any other improvements should be removed from the widening/reconstruction
areas. Existing aggregate base could remain in-place to be incorporated into the new pavement
subgrades.
After stripping, removing all improvements and completing all cuts and prior to placement of
any fill soils or overlying improvements, we recommend the in-place soils be scarified to a
minimum depth of 9 inches, adjusted in moisture content and compacted to at least 95% of the
material’s maximum dry density as determined in accordance with ASTM Specification D698,
the standard Proctor procedure. The moisture content of the scarified materials should be
adjusted to be within the range of ± 2% of standard Proctor optimum moisture content at the time
of compaction. If the exposed subgrade will be stabilized as subsequently discussed in this
report, initial scarification and re-compaction of materials which will be stabilized would not be
necessary.
Any fill materials required to develop the pavement subgrade should consist of approved, low
volume change materials which are free from organic matter and debris. Materials similar to the
on-site sandy lean clay soils could be used for fill in these areas. If borrow materials are used,
we recommend those materials have sufficient fines to prevent ponding of water in the fill
materials.
Earth Engineering Consultants, LLC
EEC Project No. 1172005
November 21, 2017
Page 5
Fill materials should be placed in loose lifts not to exceed 9 inches thick, adjusted in moisture
content and compacted as recommended for the scarified soils.
The site cohesive soils may show instability and strength loss when wetted resulting in pumping
of the pavement subgrades. If necessary, stabilization of the subgrades could be considered to
reduce the potential instability of the subgrades at the time of construction.
If stabilization will be performed, we recommend the addition of 12% Class C fly ash to the in-
place subgrade materials, based on dry weights. The Class C fly ash should be thoroughly
blended with the in-place soils to a depth of 12 inches below the top of subgrade. The blended
materials should be adjusted to be within ±2% of standard Proctor optimum moisture and
compacted to at least 95% of the materials maximum dry density as determined in accordance
with the standard Proctor procedure for stabilized materials (ASTM Specification D558).
Pavement Sections
A Hveem Stabilometer / R-value of 14 is being assumed based on the test results. That Hveem
R-value correlates to a resilient modulus value of 4060 based on the Colorado Department of
Transportation (CDOT) correlation.
The Larimer County Urban Area Street Standards (LCUASS) default equivalent daily load
application (EDLA) value of 100 for 2-lane industrial/commercial collectors was used for
Skyway Drive. A 20-year equivalent single axle load (ESAL) value of 730,000 correlates to an
EDLA of 100.
Based on the outlined subgrade and traffic inputs, alternative pavement designs are indicated
below in Table I.
Earth Engineering Consultants, LLC
EEC Project No. 1172005
November 21, 2017
Page 6
TABLE 1 –MINIMUM PAVEMENT SECTION DESIGN THICKNESSES
Skyway Road
18-kip EDLA (Based on Table 10-1 LCUASS)
Design Traffic (20 year ESAL)
(1) Resilient Modulus (R-Value of 7 for on-site soils)
Reliability
Serviceability Loss (Initial – Final)
100
730,000
4060
90%
2.0
Design Structural Number 3.98
Composite Section: Alternative A – Widening Section w/o Stabilization
Hot Mix Asphalt (HMA) Pavement: S or SX-75, PG 64-28
Hot Mix Asphalt (HMA) Pavement: SG or S-75, PG 58-28
Aggregate Base Course (ABC) (Class 5 or Class 6)
Design Weighted Structural Number (SN)
3″ @ 0.44 = 1.32
4″ @ 0.44 = 1.76
9″ @ 0.11 = 0.99
4.07
Composite Section: Alternative B – Widening Section w/ Stabilization
Hot Mix Asphalt (HMA) Pavement: S or SX-75, PG 64-28
Hot Mix Asphalt (HMA) Pavement: SG or S-75, PG 58-28
Aggregate Base Course (ABC) (Class 5 or Class 6)
Fly Ash Treated Subgrade (Upper 12-inches, 10-inches of full credit)
Design Weighted Structural Number (SN)
2″ @ 0.44 = 0.88
3″ @ 0.44 = 1.32
8″ @ 0.11 = 0.88
10″ @ 0.10 = 1.0
4.08
The HMA for use in the pavement section should be Grading S (100) with performance grading
PG 64-28 for the surface top 2-1/2 to 3-inches and 58-28 used below that depth.
The HMA should be compacted to be within the range of 92% to 96% of maximum theoretical
specific gravity (Rice value) at the time of placement. Aggregate base course should be either
Class 5 or Class 6 aggregate base and should be compacted to at least 95% of the materials
standard Proctor maximum dry density at the time of placement.
Pavement design methods are intended to provide structural sections with adequate thickness over
a particular subgrade such that wheel loads are reduced to a level the subgrade can support. The
support characteristics of the subgrade for pavement design do not account for shrink/swell
movements of either expansive or compressible clay subgrade. The pavement may be adequate
from a structural standpoint, yet still experience cracking and deformation due to shrink/swell
related movement of the subgrade. It is, therefore, important to minimize moisture changes in the
subgrade to reduce shrink/swell movements.
Earth Engineering Consultants, LLC
EEC Project No. 1172005
November 21, 2017
Page 7
Other Considerations
Positive drainage should be developed across and away from pavement edges to avoid wetting of
the pavement subgrades. Subgrade soils allowed to become wetted subsequent to construction
can result in poor pavement performance.
GENERAL COMMENTS
The analysis and recommendations presented in this report are based upon the data obtained
from the soil boring performed at the indicated location and from any other information
discussed in this report. This report does not reflect any variations which may occur across the
site. The nature and extent of such variations may not become evident until construction. If
variations appear evident, it will be necessary to re-evaluate the recommendations of this report.
It is recommended that the geotechnical engineer be retained to review the plans and
specifications so comments can be made regarding the interpretation and implementation of our
geotechnical recommendations in the design and specifications. It is further recommended that
the geotechnical engineer be retained for testing and observations during construction phases to
help determine that the design requirements are fulfilled.
This report has been prepared for the exclusive use of GYS General Contracting, LLC for
specific application to the project discussed and has been prepared in accordance with generally
accepted geotechnical engineering practices. No warranty, express or implied, is made. In the
event that any changes in the nature, design, or location of the project as outlined in this report
are planned, the conclusions and recommendations contained in this report shall not be
considered valid unless the changes are reviewed and the conclusions of this report are modified
or verified in writing by the geotechnical engineer.
Earth Engineering Consultants, LLC
DRILLING AND EXPLORATION
DRILLING & SAMPLING SYMBOLS:
SS: Split Spoon ‐ 13/8" I.D., 2" O.D., unless otherwise noted PS: Piston Sample
ST: Thin‐Walled Tube ‐ 2" O.D., unless otherwise noted WS: Wash Sample
R: Ring Barrel Sampler ‐ 2.42" I.D., 3" O.D. unless otherwise noted
PA: Power Auger FT: Fish Tail Bit
HA: Hand Auger RB: Rock Bit
DB: Diamond Bit = 4", N, B BS: Bulk Sample
AS: Auger Sample PM: Pressure Meter
HS: Hollow Stem Auger WB: Wash Bore
Standard "N" Penetration: Blows per foot of a 140 pound hammer falling 30 inches on a 2‐inch O.D. split spoon, except where noted.
WATER LEVEL MEASUREMENT SYMBOLS:
WL : Water Level WS : While Sampling
WCI: Wet Cave in WD : While Drilling
DCI: Dry Cave in BCR: Before Casing Removal
AB : After Boring ACR: After Casting Removal
Water levels indicated on the boring logs are the levels measured in the borings at the time indicated. In pervious soils, the indicated
levels may reflect the location of ground water. In low permeability soils, the accurate determination of ground water levels is not
possible with only short term observations.
DESCRIPTIVE SOIL CLASSIFICATION
Soil Classification is based on the Unified Soil Classification
system and the ASTM Designations D‐2488. Coarse Grained
Soils have move than 50% of their dry weight retained on a
#200 sieve; they are described as: boulders, cobbles, gravel or
sand. Fine Grained Soils have less than 50% of their dry weight
retained on a #200 sieve; they are described as : clays, if they
are plastic, and silts if they are slightly plastic or non‐plastic.
Major constituents may be added as modifiers and minor
constituents may be added according to the relative
proportions based on grain size. In addition to gradation,
coarse grained soils are defined on the basis of their relative in‐
place density and fine grained soils on the basis of their
consistency. Example: Lean clay with sand, trace gravel, stiff
(CL); silty sand, trace gravel, medium dense (SM).
CONSISTENCY OF FINE‐GRAINED SOILS
Unconfined Compressive
Strength, Qu, psf Consistency
< 500 Very Soft
500 ‐ 1,000 Soft
1,001 ‐ 2,000 Medium
2,001 ‐ 4,000 Stiff
4,001 ‐ 8,000 Very Stiff
8,001 ‐ 16,000 Very Hard
RELATIVE DENSITY OF COARSE‐GRAINED SOILS:
N‐Blows/ft Relative Density
0‐3 Very Loose
4‐9 Loose
10‐29 Medium Dense
30‐49 Dense
50‐80 Very Dense
80 + Extremely Dense
PHYSICAL PROPERTIES OF BEDROCK
DEGREE OF WEATHERING:
Slight Slight decomposition of parent material on
joints. May be color change.
Moderate Some decomposition and color change
throughout.
High Rock highly decomposed, may be extremely
broken.
Group
Symbol
Group Name
Cu≥4 and 1<Cc≤3
E
GW Well-graded gravel
F
Cu<4 and/or 1>Cc>3
E
GP Poorly-graded gravel
F
Fines classify as ML or MH GM Silty gravel
G,H
Fines Classify as CL or CH GC Clayey Gravel
F,G,H
Cu≥6 and 1<Cc≤3
E
SW Well-graded sand
I
Cu<6 and/or 1>Cc>3
E
SP Poorly-graded sand
I
Fines classify as ML or MH SM Silty sand
G,H,I
Fines classify as CL or CH SC Clayey sand
G,H,I
inorganic PI>7 and plots on or above "A" Line CL Lean clay
K,L,M
PI<4 or plots below "A" Line ML Silt
K,L,M
organic Liquid Limit - oven dried Organic clay
K,L,M,N
Liquid Limit - not dried Organic silt
K,L,M,O
inorganic PI plots on or above "A" Line CH Fat clay
K,L,M
PI plots below "A" Line MH Elastic Silt
K,L,M
organic Liquid Limit - oven dried Organic clay
K,L,M,P
Liquid Limit - not dried Organic silt
K,L,M,O
Highly organic soils PT Peat
(D30)2
D10 x D60
GW-GM well graded gravel with silt NPI≥4 and plots on or above "A" line.
GW-GC well-graded gravel with clay OPI≤4 or plots below "A" line.
GP-GM poorly-graded gravel with silt PPI plots on or above "A" line.
GP-GC poorly-graded gravel with clay QPI plots below "A" line.
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
Earth Engineering Consultants, LLC
IIf soil contains >15% gravel, add "with gravel" to
group name
JIf Atterberg limits plots shaded area, soil is a CL-
ML, Silty clay
Unified Soil Classification System
2
1
P-1
P-2
Boring Location Diagram
Grow Your Storage - Skyway Drive Road Widening - Fort Collins, Colorado
EEC Project Number: 1172005
November 2017
EARTH ENGINEERING CONSULTANTS, LLC
P-1 & P-2: Approximate
Locations of 2 New
Pavement Borings in
General Accordance
with LCUASS
1
Legend
Site Photos
(Photos taken in approximate
location, in direction of arrow)
GROW YOUR STORAGE – ACCEL/DECEL LANE
FORT COLLINS, COLORADO
EEC PROJECT NO. 1172005
NOVEMBER 2017
DATE:
RIG TYPE: CME55
FOREMAN: DG
AUGER TYPE: 4" CFA
SPT HAMMER: AUTOMATIC
SOIL DESCRIPTION D N QU MC DD -200
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
Existing Hot Mix Asphalt (HMA) = 5 Inches _ _
Existing Aggregate Base Course (ABC) = 6 Inches 1
_ _
SANDY LEAN CLAY (CL) 2
brown _ _ % @ 150 psf
medium stiff to stiff CS 3 12 9000+ 14.9 117.2 33 19 53.4 1400 psf 1.3%
_ _
4
_ _
SS 5 19 3500 19.2
_ _
SILTSTONE / SANDSTONE 6
brown / olive _ _
moderately hard to hard 7
_ _
8
_ _
9
_ _
SS 10 50/5" 4000 13.7
_ _
BOTTOM OF BORING DEPTH 10.5' 11
_ _
12
_ _
13
_ _
14
_ _
15
_ _
16
_ _
17
_ _
18
_ _
19
_ _
20
_ _
21
_ _
22
_ _
23
_ _
24
_ _
25
_ _
Earth Engineering Consultants, LLC
GROW YOUR STORAGE - SKYWAY DRIVE ROAD WIDENING
DATE:
RIG TYPE: CME55
FOREMAN: DG
AUGER TYPE: 4" CFA
SPT HAMMER: AUTOMATIC
SOIL DESCRIPTION D N QU MC DD -200
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
Existing Hot Mix Asphalt (HMA) = 6 Inches _ _
Existing Aggregate Base Course (ABC) = 5 Inches 1
_ _
SANDY LEAN CLAY (CL) 2
brown _ _ % @ 150 psf
medium stiff CS 3 10 1000 17.6 109.4 180 psf 0.3%
_ _
4
_ _
SS 5 10 4000 16.2
_ _
6
_ _
7
_ _
8
_ _
9
with calcareous deposits _ _
SS 10 8 3000 20.7
_ _
BOTTOM OF BORING DEPTH 10.5' 11
_ _
12
_ _
13
_ _
14
_ _
15
_ _
16
_ _
17
_ _
18
_ _
19
_ _
20
_ _
21
_ _
22
_ _
23
_ _
24
_ _
25
_ _
Earth Engineering Consultants, LLC
GROW YOUR STORAGE - SKYWAY DRIVE ROAD WIDENING
Project:
Location:
Project #:
Date:
Grow Your Storage - Skyway Drive Road Widening
Fort Collins, Colorado
1172005
Nov-17
Beginning Moisture: 14.9% Dry Density: 119.7 pcf Ending Moisture: 15.9%
Swell Pressure: 1400 psf % Swell @ 150: 1.3%
Sample Location: Boring 1, Sample 1, Depth 2'
Liquid Limit: 33 Plasticity Index: 19 % Passing #200: 53.4%
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Brown Sandy Lean Clay (CL)
-10.0
-8.0
-6.0
-4.0
-2.0
0.0
2.0
4.0
6.0
8.0
10.0
0.01 0.1 1 10
Percent Movement
Load (TSF)
Consolidatio Swell
Water Added
Project:
Location:
Project #:
Date:
Grow Your Storage - Skyway Drive Road Widening
Fort Collins, Colorado
1172005
Nov-17
Beginning Moisture: 17.6% Dry Density: 115.4 pcf Ending Moisture: 16.8%
Swell Pressure: 180 psf % Swell @ 150: 0.3%
Sample Location: Boring 2, Sample 1, Depth 2'
Liquid Limit: - - Plasticity Index: - - % Passing #200: - -
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Brown Sandy Lean Clay (CL)
-10.0
-8.0
-6.0
-4.0
-2.0
0.0
2.0
4.0
6.0
8.0
10.0
0.01 0.1 1 10
Percent Movement
Load (TSF)
Consolidatio Swell
Water Added
PROJECT: Grow Your Storage - Skyway Drive Pavements PROJECT NO. 1172005
LOCATION: DATE Nov-17
MATERIAL DESCRIPTION: Sandy Lean Clay (CL)
SAMPLE LOCATION:
LIQUID LIMIT: Pending PLASTICITY INDEX: Pending %PASSING #200: Pending
R-VALUE LABORATORY TEST RESULTS
TEST SPECIMEN NO. 1 2 3
COMPACTION PRESSURE (PSI) 100 150 175
DENSITY (PCF) 110.6 112.8 114.9
MOISTURE CONTENT (%) 17.8 16.9 15.7
EXPANSION PRESSURE (PSI) 0.00 0.00 0.00
HORIZONTAL PRESSURE @ 160 PSI 131 128 126
SAMPLE HEIGHT (INCHES) 2.56 2.47 2.45
EXUDATION PRESSURE (PSI) 227.4 329.3 400.0
UNCORRECTED R-VALUE 12.3 14.9 16.4
CORRECTED R-VALUE 12.6 14.9 16.4
R-VALUE @ 300 PSI EXUDATION PRESSURE = 14 RESILIENT MODULUS, PSI = 4,060
RESISTANCE R-VALUE & EXPANSION PRESSURE OF
COMPACTED SOIL - ASTM D2844
Fort Collins, Colorado
Composite Subgrade Sample Upper 5' - Borings P-1 and P-2
0
10
20
30
40
50
60
70
80
90
100
0 50 100 150 200 250 300 350 400 450 500 550 600
R-Value
Exudation Pressure, PSF
FORT COLLINS, COLORADO
PROJECT NO: 1172005 LOG OF BORING P-2 NOVEMBER 2017
SHEET 1 OF 1 WATER DEPTH
START DATE 11/15/2017 WHILE DRILLING None
SURFACE ELEV N/A 24 HOUR N/A
FINISH DATE 11/15/2017 AFTER DRILLING N/A
A-LIMITS SWELL
FORT COLLINS, COLORADO
PROJECT NO: 1172005 LOG OF BORING P-1 NOVEMBER 2017
SHEET 1 OF 1 WATER DEPTH
START DATE 11/15/2017 WHILE DRILLING None
SURFACE ELEV N/A 24 HOUR N/A
FINISH DATE 11/15/2017 AFTER DRILLING N/A
A-LIMITS SWELL
Soil Classification
Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests
Sands 50% or more
coarse fraction
passes No. 4 sieve
Fine-Grained Soils
50% or more passes
the No. 200 sieve
<0.75 OL
Gravels with Fines
more than 12%
fines
Clean Sands Less
than 5% fines
Sands with Fines
more than 12%
fines
Clean Gravels Less
than 5% fines
Gravels more than
50% of coarse
fraction retained on
No. 4 sieve
Coarse - Grained Soils
more than 50%
retained on No. 200
sieve
CGravels with 5 to 12% fines required dual symbols:
Kif soil contains 15 to 29% plus No. 200, add "with sand"
or "with gravel", whichever is predominant.
<0.75 OH
Primarily organic matter, dark in color, and organic odor
ABased on the material passing the 3-in. (75-mm)
sieve
ECu=D60/D10 Cc=
HIf fines are organic, add "with organic fines" to
group name
LIf soil contains ≥ 30% plus No. 200 predominantly sand,
add "sandy" to group name.
MIf soil contains ≥30% plus No. 200 predominantly gravel,
add "gravelly" to group name.
DSands with 5 to 12% fines require dual symbols:
BIf field sample contained cobbles or boulders, or
both, add "with cobbles or boulders, or both" to
group name. FIf soil contains ≥15% sand, add "with sand" to
GIf fines classify as CL-ML, use dual symbol GC-
CM, or SC-SM.
Silts and Clays
Liquid Limit less
than 50
Silts and Clays
Liquid Limit 50 or
more
0
10
20
30
40
50
60
0 10 20 30 40 50 60 70 80 90 100 110
PLASTICITY INDEX (PI)
LIQUID LIMIT (LL)
ML OR OL
MH OR OH
For Classification of fine-grained soils and
fine-grained fraction of coarse-grained
soils.
Equation of "A"-line
Horizontal at PI=4 to LL=25.5
then PI-0.73 (LL-20)
Equation of "U"-line
Vertical at LL=16 to PI-7,
then PI=0.9 (LL-8)
CL-ML
HARDNESS AND DEGREE OF CEMENTATION:
Limestone and Dolomite:
Hard Difficult to scratch with knife.
Moderately Can be scratched easily with knife.
Hard Cannot be scratched with fingernail.
Soft Can be scratched with fingernail.
Shale, Siltstone and Claystone:
Hard Can be scratched easily with knife, cannot be
scratched with fingernail.
Moderately Can be scratched with fingernail.
Hard
Soft Can be easily dented but not molded with
fingers.
Sandstone and Conglomerate:
Well Capable of scratching a knife blade.
Cemented
Cemented Can be scratched with knife.
Poorly Can be broken apart easily with fingers.
Cemented