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600 - Laboratory Testing

Published: July 15, 2022

601 General

The purpose of the laboratory testing is as follows:

  • Classify all soil, rock, and man-made materials which have been sampled
  • Define physical properties to be used for the design and construction of the project

Only qualified personnel working under the supervision of a licensed Professional Engineer may perform laboratory testing. Use only appropriate AASHTO or ASTM standard test methods unless otherwise stated herein or requested by the District Geotechnical Engineer. Develop the testing program so as to provide the necessary data in the most efficient manner. Refer to “Geotechnical Engineering Circular No. 5, Geotechnical Site Characterization,” FHWA NHI-16-072, for state of the practice laboratory testing information. This publication is available on the internet.

Soils having widely different physical characteristics are encountered throughout Ohio. To simplify the presentation and facilitate the interpretation of soils information for design and construction purposes, use the ODOT Soil Classification Chart, as shown in Figure 600-1. Perform all subsurface explorations for ODOT by classifying soils and miscellaneous materials according to this chart.

Determine the water content and visually describe every soil sample. Select a sufficient number of soil samples for classification testing to define the subsurface conditions. For each boring, perform at least one classification test for each distinct soil stratum encountered and for all samples at critical locations and depths related to stability, settlement, unsuitable materials, subgrade, or foundation design, including scour. Use classification testing to confirm or modify the visual descriptions of samples.

Visually describe all bedrock samples according to Section 605.

602 Visual Description of Soils

Determine the water content and visually describe every soil sample. Visually describe the soil samples using techniques and terminology described herein when manipulating and examining a soil. Use terms in the description of soils in the following order: compactness or consistency, color, primary component, secondary component(s) with modifier(s), supplementary descriptive terms (when appropriate), and water content.

Following are two examples of visual soil descriptions:

  • Medium dense, brown COARSE AND FINE SAND, some gravel, trace silt and clay, well-graded, wet
  • Very stiff, mottled brown and yellow CLAY, some sand, little stone fragments, moist

Since visual descriptions are based on estimates of particle size distribution and plasticity characteristics, it may be difficult to clearly identify the soil’s primary component. Secondary components may be used to describe primary components, such as silty clay or sandy silt, when the anticipated classification calls for it (see descriptions in Figure 600-1) or to indicate the soil may fall into one of two possible primary groups (i.e., borderline classifications).

Visually inspect each soil sample representing proposed pavement subgrade for the presence of gypsum (CaSO4·2H2O). Gypsum crystals are soft (easily scratched by a knife; they will not scratch a copper penny), translucent (milky) to transparent, and do not have perfect cleavage (do not split into thin sheets). Photos of gypsum crystals are shown in Supplement 1120. If gypsum is present, test the sample for sulfate content in accordance with Supplement 1122.

602.1 Compactness or Consistency

Use the terms defined herein to refer to the relative compactness of a non-cohesive soil (ODOT Classifications A-1, A-2, A-3, and non-plastic A-4 and A-8) and to the relative consistency of a cohesive soil (ODOT Classifications plastic A-4 and A-8, A-5, A-6, and A-7).

602.1.1 Non-Cohesive Soils

Describe the relative compactness of non-cohesive soils according to Table 600-1:

Table 600-1. Relative Compactness of Non-Cohesive Soils


Description

Standard Penetration
Blows Per Foot, N60

Very Loose

Less than 5

Loose

5 – 10

Medium Dense

11 – 30

Dense

31 – 50

Very Dense

Greater than 50

602.1.2 Cohesive Soils

Describe the relative consistency of cohesive soils according to Table 600-2. Unconfined compressive strength is preferred over standard penetration for description of relative consistency.

602.2 Color

Describe the color of the soil in clear and concise terms, such as: brown, gray, or black. Where two major and distinct colors are present, use both in the description, such as: brown and gray. Where a major color appears to be modified by a secondary color, refer to the modifying color first, such as: yellowish-brown, or greenish-gray. Where two major and distinct colors appear swirled in the soil, describe the colors as mottled, such as: mottled brown and gray.

Table 600-2. Relative Consistency of Cohesive Soils

 

Description

Unconfined Compressive Strength*, tsf (kPa)

Standard Penetration
Blows Per Foot, N60

 

Hand Manipulation

Very Soft

Less than 0.25 (24)

Less than 2

Easily penetrated 2 in. by fist

Soft

0.25 – 0.5 (24 – 48)

2 – 4

Easily penetrated 2 in. by thumb

Medium Stiff

0.5 – 1.0 (48 – 96)

5 – 8

Penetrated by thumb with moderate effort

Stiff

1.0 – 2.0 (96 – 192)

9 – 15

Readily indented by thumb but not penetrated

Very Stiff

2.0 – 4.0 (192 – 383)

16 – 30

Readily indented by thumbnail

Hard

Greater than 4.0 (383)

Greater than 30

Indented with difficulty by thumbnail

*As determined by hand penetrometer or torvane tests.

602.3 Components

Use the particle sizes in Table 600-3 to describe the components of the soil:

Table 600-3. Description of Particle Size

Component

Size

Boulders

Larger than 12 in. (300 mm)

Cobbles

3 in. to 12 in.

(75 mm to 300 mm)

 

Gravel

Coarse

¾ in. to 3 in. (19 mm to 75 mm)

Fine

#10 sieve to ¾ in. (2.0 mm to 19 mm)

 

Sand

Coarse

#40 sieve to #10 sieve

(0.42 mm to 2.0 mm)

Fine

#200 sieve to #40 sieve

(.074 mm to 0.42 mm)

Silt

0.005 mm to #200 sieve (0.005 mm to 0.074 mm)

Clay

Smaller than 0.005 mm

Differentiate between silts and clays by manipulation as follows:

602.3.1 Silt

When subjected to shaking in the palm of the hand, a pat of saturated inorganic silt expels enough water to give a glossy appearance to the surface and, when bent or slightly squeezed between the fingers, the surface of the pat will become dull. The pat, upon working in the hand, loses moisture, becomes brittle, and breaks easily into very fine particles.

602.3.2 Clay

Clay is sticky at high water contents, plastic over a wide range of water contents, and can be rolled into a fine thread without breaking. Upon drying it becomes hard and will not break into fine particles.

602.4 Identification of Components

Describe soil components as: gravel, stone fragments, sand, silt, clay, organic materials such as root fibers or wood fragments, miscellaneous materials such as uncontrolled fill, or peat, or any combination thereof.

602.4.1 Organics in Soils Except Peat

Describe organics by characteristics such as smell, texture, staining, color, or presence of organic material.

602.4.2 Peat Soils

Describe soils composed primarily of plant tissue in various stages of decomposition and having a fibrous to amorphous texture, a dark brown to black color, and an organic odor as a peat. Distinguish among various peat soils according to its composition, for example, woody peat, fibrous peat, sedimentary peat, fine textured peat, loamy peat, marly peat, marls, or various combinations thereof.

602.4.3 Gravel and Stone fragments

Differentiate between gravel and stone fragments as follows: Gravel is rounded or sub- rounded pieces of rock exposed to either stream or glacial abrasion. Stone fragments are angular pieces of rock subjected to little or no abrasive action or manufactured materials such as blast furnace slag.

602.5 Modifiers of Components

Use modifiers of components according to Table 600-4:

Table 600-4. Modifiers of Components

Term

Percent By Weight

Trace

0 to 10

Little

> 10 to 20

Some

> 20 to 35

And

 > 35

602.6 Supplementary Descriptive Terms

Use supplemental descriptive terms for additional information when appropriate, such as: glacial till, alluvial, or residual type of manufactured material (i.e. slag, recycled asphalt or concrete, etc).

Use secondary descriptive terms such as: a description of foreign material, organic odor, fissures, voids or cavities, staining, or lenses.

602.7 Water Content

Describe the relative water content of the soil samples according to Table 600-5:

Table 600-5. Water Content of Soils

Term

Criteria

 

Dry

  • Soil leaves no moisture when pressed between fingers.
  • For cohesive soils, is brittle to powdery.
  • Water content well below the plastic limit

 

Damp

  • Soil leaves very little moisture when pressed between fingers.
  • Soil contains a small amount of moisture.
  • Water content below the plastic limit.

 

Moist

  • Soil leaves small amount of moisture when pressed between fingers.
  • Water content above the plastic limit to -3% of the liquid limit.

 

Wet

  • For cohesive soils, the water content is near or above the liquid limit.
  • For non-cohesive soils, the pore space is filled with water and water can be poured from sample with ease.

603 Soil Classification

603.1 ODOT Soil Classification Method

Classify soils by their physical characteristics using the ODOT Soil Classification Chart, shown in Figure 600-1, based on test data for grain size distribution, liquid limit, and plasticity index. Classify soils by proceeding from top to bottom of the chart. Place a soil in the first classification in which the properties of the soil meet all the requirements of that classification.

The ODOT Soil Classification Chart is in general agreement with the "Classification of Soils and Soil Aggregate Mixtures for Highway Construction Purposes", AASHTO M 145, with modifications. These modifications have been made as a result of ODOT's experience with the behavior of subgrade and foundation soils encountered in Ohio.

The ODOT Soil Classification Chart provides for the classification of all materials commonly encountered in subsurface explorations. These materials are grouped into three general categories, as follows.

  • Granular material, having 35 percent or less by weight passes the No. 200 U.S. Standard sieve
  • Silt-clay material, having more than 35 percent by weight passes the No. 200 U.S. Standard sieve
  • Miscellaneous materials classified by visual inspection and not readily identified by the tests used for classification of soils

The first two categories are similar to those of the AASHTO classification system while the third category is a provision only of the ODOT Soil Classification Chart. The classifications within these categories are discussed in the following paragraphs.

The classifications for granular materials are the same as those adopted by AASHTO with the following exception: granular materials containing a minimum of 50 percent by dry weight of coarse and fine sand sizes and a maximum plasticity index of 6 have been classified as Group A-3a.

The classifications for silt-clay materials of the AASHTO classification have been modified as follows:

  1. The A-4 classification has been divided into A-4a and A-4b. A-4a soils are sandy silt soils containing less than 50 percent silt sizes. A-4b soils are predominantly silts containing not less than 50 percent silt sizes. Silt sizes are particles passing the No. 200 U.S. Standard sieve, or smaller than 0.074 millimeter, and larger than 0.005 millimeter in diameter.
  2. The A-6 classification has been divided into A-6a and A-6b. A-6a soils are predominantly silts and clays having a maximum liquid limit of 40 and a plasticity index of 11 to 15 inclusive. A-6b materials are silty clays with a maximum liquid limit of 40 and a plasticity index of 16 or greater.
  3. The A-8 classification is an optional AASHTO classification which is adopted by ODOT for organic silt or clay soils, not including peat. A-8 soils are defined as those soils which would otherwise classify as A-4, A-5, A-6, or A-7, but have a liquid limit value after oven drying less than 75 percent of its liquid limit before oven drying. The A-8 classification has been divided into A-8a and A-8b. A-8a soils are sandy silt soils which otherwise would have classified as an A-4 soil and exhibit the loss in liquid limit value upon oven drying as noted above. A-8b soils are predominantly silts and clays which otherwise would have classified as an A-5, A-6, or A-7 soil and exhibit the loss in liquid limit value upon oven drying as noted above.

The classification of miscellaneous materials is also provided by the ODOT Soils Classification Chart. These materials, which are commonly encountered in subsurface explorations, do not lend themselves to standard laboratory classification tests and are therefore classified by visual inspection based on their general character or geologic nature.

Figure 600-1. ODOT Soil Classification Chart

Figure 600-1


Examples of miscellaneous materials include topsoil, pavement and base, berm material, uncontrolled fill, cobble or boulder zones, and peat.

The AASHTO classification system provides a parameter for the characterization of soils referred to as the Group Index. This methodology has been included in the Ohio Classification Chart with modifications. Modifications to the AASHTO Group Index consist of limiting the value of the Group Index to 0 to 20, based on an empirical formula, weighted to take into account variations in the percentage of coarse material, the liquid limit, and the plasticity index. Assuming good drainage and thorough compaction, the suitability of soils as subgrade materials is inversely related to the Group Index. That is to say, the lower the Group Index, the better the supporting characteristics of the soil as a subgrade material. The modified empirical formula is as follows:

Group Index = 0.2A + 0.005AC + 0.01BD

where:

A = That portion of the percentage passing the No. 200 sieve greater than 35 percent and not exceeding 75 percent, expressed as a positive whole number (0 to 40).

B = That portion of the percentage passing the No. 200 sieve greater than 15 percent and not exceeding 55 percent, expressed as a positive whole number (0 to 40).

C = That portion of the numerical liquid limit greater than 40 and not exceeding 60, expressed as a positive whole number (0 to 20).

D = That portion of the numerical plasticity index greater than 10 and not exceeding 30 expressed as a positive whole number (0 to 20).

603.2 Testing Requirements

Classify representative soil samples by the ODOT Soil Classification Method. Perform the tests listed in Table 600-6 utilizing either AASHTO or ASTM test methods, except modify the Particle- Size Analysis according to Section 603.3.

Table 600-6. Testing Requirements for Classification of Soils

Test Method

AASHTO
Designation

ASTM
Designation

Water Content Determination

T 265

D 2216

Organic Content by Loss on Ignition

T 267

D 2974

Particle-Size Analysis

T 88

D 422*

Liquid Limit

T 89

D 4318

Plastic Limit and Plasticity Index

T 90

D 4318

* D 422 is withdrawn from ASTM Standards but should continue to be used until a replacement procedure is identified.

603.3 Modifications to Test Methods

603.3.1 Organic Content by Loss on Ignition

Perform the organic content by loss on ignition test only on samples visually described as moderately to highly organic or as peat.

603.3.2 Particle-Size Analysis

Perform the particle-size analysis of soils as described by AASHTO T 88 or ASTM D 422 except:

  • Limit the length of the hydrometer test to two hours
  • Do not perform the hydrometer test on non-cohesive materials essentially free of material passing the No. 200 U.S. standard sieve, as determined by visual inspection

603.3.3 Plastic Limit and Plasticity Index

Perform the plastic limit test prior to performing the liquid limit test.

603.3.4 Liquid Limit

Determine the liquid limit of soils as described by AASHTO T 89 or ASTM D 4318 only on samples determined to be plastic by means of the plastic limit test.

Determine the liquid limit of silt-clay soils visually described as moderately to highly organic on each sample twice. First determine the liquid limit when prepared by air drying as described by AASHTO R 58 or ASTM D 421 dry preparation method. Then determine the liquid limit on the same sample when prepared by oven drying as described by AASHTO T 265 or ASTM D 2216.

603.4 Organic Silts and Clays

Designate organic silts and organic clays as such when they have sufficient organic content to influence the soil properties. Classify a soil as an A-8a organic silt when it would have otherwise classified as an A-4 soil and its liquid limit value after oven drying is less that 75 percent of its liquid limit value before oven drying. Classify a soil as an A-8b organic clay when it would have otherwise classified as an A-5, A-6, or A-7 soil and its liquid limit value after oven drying is less that 75 percent of its liquid limit value before oven drying. Perform the organic content by loss on ignition test to determine the percent organic content.

603.5 Granular and Silt-Clay Soils Containing Organics

Classify granular soils and silt-clay soils which contain organics but retain 75 percent or more of its liquid limit value after oven drying according to the ODOT classifications A-2 through A-7. Verify the organic content of soils containing organic material visually described as moderately to highly organic by performing the organic content by loss on ignition test. Modify, as necessary, the description of the soil according to Table 600-7:

Table 600-7. Organic Content of Soils

Percent of Organic Matter
(By Weight)

Description

2 to 4

Slightly Organic

4 to 10

Moderately Organic

> 10

Highly Organic

603.6 Peat Soils

Do not subject samples visually identified as peat to further classification testing. Unless the peat is fibrous or woody, perform the organic content by loss on ignition test to determine the percent organic content.

603.7 Sulfate Content in Soils

Use the test procedure described in Supplement 1122 for the determination of the sulfate content of soils.

604 Strength and Consolidation Testing of Soils

Perform strength and consolidation testing when necessary for design of the project. Do not test undisturbed samples until after related samples have been classified to determine the nature of subsurface conditions.

604.1 Laboratory Strength and Consolidation Test Methods

Use only relatively undisturbed samples, successfully obtained using a thin-walled tube of suitable diameter per AASHTO T 207 or ASTM D 1587. Classify the undisturbed samples by performing testing on a portion of the sample as described above. In addition, test samples selected for strength or consolidation determinations using the appropriate test methods from the list below. Use either AASHTO or ASTM test methods:

Table 600-8. Strength and Consolidation Testing Requirements for Soils

Test Method

AASHTO
Designation

ASTM
Designation

Unconfined Compressive Strength

T 208

D 2166

Direct Shear

T 236

D 3080

Unconsolidated-Undrained Triaxial Compression

T 296

D 2850

Consolidated-Undrained Triaxial Compression

T 297

D 4767

One-Dimensional Consolidation

T 216

D 2435

Specific Gravity

T 100

D 854

604.2 Index Strength Tests

Perform index strength tests such as hand penetrometer and torvane tests according to manufacturer's instructions. Do not rely solely on these index strength results to determine strength parameters for final design. Use these results for relative consistency and strength, and comparative indication to anticipated and achieved laboratory and field test results.

604.3 Other Tests

Perform other tests, when necessary for design of the project, with prior approval from the District Geotechnical Engineer.

605 Bedrock Description

605.1 General

Bedrock encountered in Ohio is sedimentary. Metamorphic and igneous rocks are encountered only in the form of gravel, cobbles, and boulders, which were carried and deposited into the state as a result of glaciation.

Visually describe all bedrock encountered. Use terms described herein for the description of bedrock, which may include in the following order: bedrock type, color, degree of weathering, strength, texture, bedding, other descriptors, type and condition of discontinuities, unit RQD, and unit recovery. Unit RQD, and unit recovery are not required for bedrock exposures or rock sampled by means other than a core barrel.

Following are two examples of visual rock descriptions:

  • Sandstone, gray, unweathered, strong, very fine to coarse grained, thick bedded, argillaceous, Unit RQD 90%, Unit Recovery 95%
  • Shale, variegated brown and gray, moderately weathered, slightly strong, thin bedded to laminated, fissile, jointed, moderately fractured, narrow, slightly rough, Unit RQD 85%, Unit Recovery 100%

605.2 Bedrock Type

Determine the type of in-place bedrock based upon its physical characteristics. The primary bedrock types encountered in Ohio are: claystone, coal, dolomite, limestone, sandstone, shale, siltstone, and underclay. Refer to Appendix A for a complete listing and brief description of all rock types.

When alternating layers occur between two distinct rock types describe the material as “Interbedded” with the major rock type first, with estimated percentage, and the secondary rock type second, with estimated percentage. Provide the unit RQD and unit recovery, then describe each rock type in detail, such as:

  • Interbedded Shale (70%) and Limestone (30%), Unit RQD 50%, Unit Recovery 90%;
  • Shale, gray, moderately weathered, weak, laminated, calcareous, blocky, fair; ranges in thickness from 8 inches to 24 inches;
  • Limestone, light gray, slightly weathered, moderately strong, thin bedded, fossiliferous, blocky, good; ranges in thickness from 2 inches to 6 inches

605.3 Color

Determine the color of the bedrock using the wet color of the rock. Describe the color of the bedrock, for example: brown, gray, or black. Colors may be modified as light or dark. If the primary color appears to be tinted by a secondary color, refer to the secondary color first, such as: greenish-gray, yellowish-brown, or brownish-gray. Where two or more major and distinct colors appear in the rock, describe the color as variegated, such as: variegated red and gray.

605.4 Weathering

Describe the degree of weathering of the rock mass according to Table 600-9. Do not describe weathering for coal, fireclay, or underclay.

Table 600-9. Weathering of Bedrock

Description

Parameters

Unweathered

No evidence of any chemical or mechanical alternation of the rock mass. Mineral crystals have a bright appearance with no discoloration. Fractures show little or no staining on surfaces.


Slightly Weathered

Slight discoloration of the rock surface with minor alterations along discontinuities. Less than 10 percent of the rock volume presents alteration.


Moderately Weathered

Portions of the rock mass are discolored as evident by a dull appearance. Surfaces may have a pitted appearance with weathering “halos” evident. Isolated zones of varying rock strengths due to alteration may be present. 10 to 15 percent of the rock volume presents alterations.

Highly Weathered

Entire rock mass appears discolored and dull. Some pockets of slightly to moderately weathered rock may be present and some areas of severely weathered materials may be present.


Severely Weathered

Majority of the rock mass reduced to a soil-like state with relic rock structure discernable. Zones of more resistant rock may be present, but the material can generally be molded and crumbled by hand pressures.

605.5 Relative Strength

Describe the relative strength of the bedrock according to Table 600-10:

Table 600.10. Strength of Bedrock

 

Description

 

Field Parameters

Range of Unconfined Compressive Strength

psi (ksf)

MPa

 

Extremely Strong

Cannot be scratched by a knife or sharp pick. Chipping of hand specimens requires hard repeated blows of the geologist hammer.

Greater than 30,000

(> 4320)

 

Greater than 200

 

Very Strong

Cannot be scratched by a knife or sharp pick. Breaking of hand specimen requires hard repeated blows of the geologist hammer.

 

15,000 to 30,000

(2160 to 4320)

 

100 to 200

 

Strong

Can be scratched with a knife or pick only with difficulty. Requires hard hammer blows to detach hand specimen. Sharp and resistant edges are present on hand specimen.

 

7500 to 15,000

(1080 to 2160)

 

50 to 100

 

Moderately Strong

Can be scratched with a knife or pick. Grooves or gouges to ¼” (6mm) deep can be excavated by hand blows of a geologist’s pick. Requires moderate hammer blows to detach hand specimen.

 

3600 to 7500

(520 to 1080)

 

 

25 to 50

 

Slightly Strong

Can be grooved or gouged 0.05 inch (2 mm) deep by firm pressure of a knife or pick point. Can be excavated in small chips to pieces about 1-inch (25 mm) maximum size by hard blows of the point of a geologist’s pick.

 

1500 to 3600

(215 to 520)

 

10 to 25

 

Weak

Can be grooved or gouged readily by a knife or pick. Can be excavated in small fragments by moderate blows of a pick point. Small, thin pieces can be broken byfinger pressure.

 

750 to 1500

(108 to 215)

 

 

5 to 10

 

Very Weak

Can be carved with a knife. Can be excavated readily with a point of a pick. Pieces 1 inch (25 mm) or more in thickness can be broken by finger pressure. Can be scratched by fingernail.

 

40 to 750

(6 to 108)

 

 

0.3 to 5

605.6 Texture

Describe the rock texture by the grain size of the parent material from which the rock is composed. Use the particle sizes in Table 600-11, which are based upon the American Geological Institute, to describe the rock texture:

Table 600-11. Texture of Bedrock

Component

Particle Size

Boulder

Larger than 12 in.

Larger than 300 mm

Cobbles

3 in. to 12 in.

75 mm to 300 mm

Gravel

0.08 in. to 3 in.

2 mm to 75 mm

 

 

 

Sand

Coarse

0.02 in. to 0.08 in. (#35 to #10 sieve)

0.5 mm to 2 mm

Medium

0.01 in. to 0.02 in. (#60 to #35 sieve)

0.25 mm to 0.5 mm

Fine

0.005 in. to 0.01 in. (#120 to #60 sieve)

0.125 mm to 0.25 mm

Very Fine

0.003 in. to 0.005 in. (#200 to #120 sieve)

0.074 mm to 0.125 mm

605.7 Bedding

The bedding thickness is the average perpendicular distance between bedding surfaces. Describe bedding thicknesses according to Table 600-12:

Table 600-12. Bedding Thickness of Bedrock

Description

Thickness

Very Thick

Greater than 36 in. (> 1000 mm)

Thick

18 in. to 36 in.

(500 mm to 1000 mm)

Medium

10 in. to 18 in.

(250 mm to 500 mm)

Thin

2 in. to 10 in.

(50 mm to 250 mm)

Very Thin

0.4 in. to 2 in. (10 mm to 50 mm)

Laminated

0.1 in. to 0.4 in. (2.5 mm to 10 mm)

Thinly Laminated

Less than 0.1 in. (< 2.5 mm)

605.8 Descriptors

Describe secondary characteristics of bedrock as necessary. Use no more than three characteristics in the description. Use the list of common terms, which are defined in Appendix A.

  • Arenaceous
  • Calcareous
  • Clay Seams
  • Dolomitic
  • Fossiliferous
  • Lithic
  • Siliceous
  • Vitreous
  • Argillaceous
  • Carbonaceous
  • Conglomeritic
  • Ferriferous
  • Friable
  • Micaceous
  • Stylolitic
  • Coal Stringer
  • Brecciated
  • Cherty
  • Crystalline
  • Fissile
  • Iron Stained
  • Pyritic
  • Vuggy

605.9 Discontinuities

When a bedrock description is necessary due to a design element relative to the condition of the bedrock, such as a foundation supported on/or into bedrock or a cut slope within bedrock, provide a description of the bedrock discontinuities. Typically, for spread footings founded on/or into bedrock, utilize a modified Rock Mass Rating (RMR) description of the discontinuities as outlined in Section 605.9.1. For drilled shafts extending into bedrock provide a Geologic Strength Index (GSI) description of the discontinuities as outlined in Section 605.9.2. For rock cut slopes, utilize both modified RMR and GSI discontinuities descriptions as outlined in Section 605.9.1 and 605.9.2.

605.9.1 Description Utilizing Modified RMR

Describe discontinuities according to Table 600-13:

Table 600-13. Discontinuities in Bedrock

 

Description

 

Parameters

 

Fault

Fracture which expresses displacement parallel to the surface that does not result in a polished surface.

 

Joint

Planar fracture that does not express displacement. Generally occurs at regularly spaced intervals.

 

Shear

Fracture which expresses displacement parallel to the surface that results in polished surfaces or slickensides.

 

Bedding

 

A surface produced along a bedding plane.

 

Contact


A surface produced along a contact plane. (generally not seen in Ohio)

When the discontinuity is a fracture (i.e. fault, joint, or shear), describe the degree and condition of the fracturing. Determine the degree of fracturing based on the average distance between recognized natural fractures. Describe the conditions of the fractures based on average aperture width and surface roughness, as shown in Tables 600-14 and 600-15:

Table 600-14. Degree of Fracturing in Bedrock

Description

Spacing

Unfractured

Greater than 10 ft.

Intact

3 ft. to 10 ft.

Slightly Fractured

1 ft. to 3 ft.

Moderately Fractured

4 in. to 12 in.

Fractured

2 in. to 4 in.

Highly Fractured

Less than 2 in.

Table 600-15. Condition of Fractures in Bedrock

A. Aperture Width

Description

Width

Open

Greater than 0.2 in.

Greater than 5.0 mm

Narrow

0.05 in. to 0.2 in.

1.0 mm to 5.0 mm

Tight

Less than 0.05 in.

Less than 1.0 mm

B. Surface Roughness

Description

Criteria

Very Rough

Near vertical steps and ridges occur on the discontinuity surface

Slightly Rough

Asperities on the discontinuity surface are distinguishable and can be felt.

Slickensided

Surface has a smooth, glassy finish with visual evidence of striations.

605.9.2 Description Utilizing GSI

Describe discontinuities according to Table 600-16:

Table 600-16. Structure

 

Description

 

Parameters


Intact or Massive


Intact rock with few widely spaced discontinuities


Blocky


Well interlocked undisturbed rock mass consisting of cubical blocks formed by three interesting discontinuity sets

Very Blocky

Interlocked, partially disturbed mass with multi- faceted angular blocks formed by 4 or more joint sets

Blocky/Disturbed/Seamy

Angular blocks formed by many intersecting discontinuity sets, Persistence of bedding planes


Disintegrated

Poorly interlocked, heavily broken rock mass with mixture of angular and rounded rock pieces


Laminated/Sheared

Lack of blockiness due to close spacing of weak shear planes

Table 600-17. Surface Condition

 

Description

 

Parameters


Very Good


Very rough, fresh unweathered surfaces

 

Good

 

Rough, slightly weathered, iron stained surface

Fair

Smooth, moderately weathered and altered surfaces


Poor

Slickensided, highly weathered surface with compact coatings or fillings or angular fragments


Very Poor

Slickensided, highly weathered surfaces with soft clay coating or fillings

605.10 Rock Quality Designation (RQD)

The Rock Quality Designation, RQD, is an index of fracture frequency. Determine the RQD value for each core run (Run RQD) and for the total length of each bedrock unit encountered by a boring (Unit RQD). The RQD value is calculated by adding up the total length of each rock core piece which is 4 inches, or longer, and dividing by the total length of the core run or total rock unit thickness. Express the value as a percentage. Take measurements along the centerline axis of the core. Consider only natural fractures for the RQD determination, discounting mechanical breaks resulting from the drilling operations or transport of the core. If there are fractures that cannot be determined to be either mechanical or natural, consider these to be natural. Figure 600-2 illustrates the procedure for calculating RQD.

Figure 600-2. Typical RQD Calculation

Figure 600-2

605.11 Core Recovery

Calculate core recovery within each core run (Run Recovery) and for each rock unit (Unit Recovery). Calculate the run recovery for each core run, expressed as a percentage, by the following equation.

Recovery run formula

Where:

RR = Length of recovered core of the core run.
LR = Length of the core run

Calculate the unit recovery for each rock unit, expressed as a percentage, by the following equation.

Unit recovery

Where:

RU = Length of recovered core for the bedrock unit.
LU = Length of core run for the bedrock unit.

606 Testing of Rock

606.1 Test Methods

When necessary for design of the project, perform testing on rock according to the test methods listed in Table 600-18:

Table 600-18. Rock Testing Methods

TEST METHOD

ASTM DESIGNATION

Slake Durability

D 4644

Point Load Strength Index

D 5731

Unconfined Compressive Strength of Intact Rock

D 7012, Method C

Compressive Strength and Elastic Moduli

D 7012, Method D

606.2 Other Tests

Perform other tests necessary for the design of the project, with prior approval of the District Geotechnical Engineer.

607 Method of Payment

Laboratory Testing is an engineering service to be performed and paid for according to the engineering agreement and the Specifications for Consulting Services.

The method of compensation for the work involved in Laboratory Testing will be unit cost. The quantities of pay items for Laboratory Testing will be the actual number of units completed and accepted. The unit prices in the engineering agreement for the respective pay items shall include all testing, determinations, measurements, computations, tabulations, and other work required in the performance of the tests; technical supervision and engineering oversight; and services, labor, storage, equipment, transportation, materials, and supplies necessary for and incidental to the completion of the laboratory testing work specified herein, including work reasonably implied. A unit for the direct shear test and consolidated-undrained triaxial compression test will include testing of three specimens. Payment for the visual description of bedrock will be included in the cost of procuring the bedrock cores.

The quantities of pay items for Laboratory Testing shall be the actual number of units completed and accepted. The basis of payment shall be the quantity of accepted work multiplied by the unit price in the engineering agreement for each of the items of Laboratory Testing.

Pay items for Laboratory Testing according to Table 600-19:

Table 600-19. Method of Payment

Description

Unit

Unit Price

Water Content Test and Visual Description

Each

$16

Classification Package, per Table 600-6, excluding Organic Content by Loss on Ignition, and including Visual Description and Hydrometer

 

Each

 

$199

Organic Content by Loss on Ignition

Each

$60

Liquid Limit Test

Each

$44

Plastic Limit Test

Each

$43

Particle Size Analysis--Sieve and Hydrometer

Each

$113

Particle Size Analysis--Sieve Only**

Each

$86

Unconfined Compression Test on Soil

Each

$91

Direct Shear Test

Each

$580*

Unconsolidated-Undrained Triaxial Compression Test

Each

$193

Consolidated-Undrained Triaxial Compression Test

Each

$1,032

One-Dimensional Consolidation Test

Each

$585

Specific Gravity Test

Each

$76

Slake Durability

Each

$243

Point Load Strength Index

Each

$75

Unconfined Compressive Strength of Intact Rock

Each

$110

Compressive Strength and Elastic Moduli on Rock

Each

$278

Misc.:

Each

 

* Unit price assumes intact specimens with a maximum time to failure of 24 hours each.

** Sieve Only includes a dry sieve on the #200 (no wash sieve).