Ohio Department of Transportation

Ohio Department of Transportation Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum Office of Geotechnical Engineering

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum AGENDA • 08:30 10:30 Soil Classification • 10:30 10:45 Break • 10:45 11:30 Soil Classification – Hands On • 11:30 12:30 Lunch – On Own • 12:30 14:30 Rock Classification • 14:30 14:45 Break • 14:45 16:00 Rock Classification – Hands On • 16:00 16:15 Break • 16:15 17:00 Practical Exam

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum Instructors • Adam Willis: Geologist with ODOT since 2009. Prior to ODOT worked as a Consultant for 11 years. Currently geotechnical laboratory manager for ODOT. • P. Paul Painter: Geologist with ODOT since 2005. Prior to ODOT worked as a Consultant for 11 years. Currently working in Design Resources Group managing Geohazard Inventory

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum Purpose: • To inform and train all field persons who visually classify borehole samples (soil and rock). • Developed to ensure high quality and consistency in the field classification of samples during subsurface explorations . • Follows the Ohio Department of Transportation’s (ODOT) Specifications for Subsurface Explorations (SGE) - 2011. http://www.dot.state.oh.us/Divisions/Engineering/Geotechnical/Pages/SGE.aspx

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum Common Soil Classifications AASHTOAmerican Association State Highway and Transportation Officials • Standard for Several DOT Geotechnical Engineers • Classification geared for the design and construction of roadways • A-1-a is the best pavement subgrade USCSUnified Soil Classification System • Standard for non D.O.T. Geotechnical Engineers USDA United States Department of Agriculture • Standard for Agronomy (farming) • Soil Taxonomy

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum ODOT SOIL CLASSIFICATION ODOT utilizes a modified AASHTO system AASHTO system covered under M 145 Based on gradation and plastic index (PI) Percentages are based on: dry weight not volume Break point between granular and cohesive soils is 35% passing #200 sieve.

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum Most Soils have a mixture of different particle sizes being gravel, sand, silt and/or clay. The percentage of each will determine the classification • Granular Soils -vs- Cohesive Soils Determined based on Percentage of gravel and sand to silt an clay.

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum Review of Soil Properties • Particle Sizes • Plasticity • Dilatency

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum Based on AASHTO

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum Gravel and Sand– Visible to the naked eye and can be visually estimated. 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. 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.

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum Plasticity of Cohesive Soils • Plasticity determined through Atterburg Limits: • Liquid Limit Test (LL) • Plastic Limit Test (PL)

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum Plasticity Index (PI) = LL – PL PI is the basic measure of the nature of a fine-grained soil. Four (4) states of fine-grained soil relative to PI and moisture content: • Solid • Semi-solid • Plastic • Liquid

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum Plastic Limit Moisture content (%) at which the soil can be rolled into 1/8 in diameter thread, or the boundary between non-plastic and plastic state.

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum Field Plastic Limit • Select test soil at natural moisture • Remove any non-soil materials (i.e. rock, roots, etc.) • Roll sample between palms • Does it reach a uniform 1/8 inch diameter thread • Yes – above plastic limit • No – below plastic limit

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum Liquid Limit Moisture content (%) at which the soil crosses the boundary from a plastic state to a liquid state.

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum Field Liquid Limit As a soil is wetted from either a dry or natural moisture content the stickiness will indicate it’s relative plasticity. Stickiness estimates the soil’s capacity to adhere to other objects. Try to utilize a moisture content that displays the maximum adherence of the soil between the thumb and fore finger after it is squeezed together.

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum Non-Sticky Slightly Sticky Very Sticky

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum ODOT Soil Sample Description • Consistency or Compactness • Color • Primary Component (Classification) • Modifiers of Components • Supplementary Descriptive Terms • Water Content

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum Consistency or Compactness Cohesive Soils are Described by Consistency Granular Soils are Described by Compactness

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum Pocket Penetrometer Torvane

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum • N60=Nmeasuredx (ERi/60) • ERi= Hammer energy ratio

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum Color • Important property in identifying organic soils, and it may also be useful in identifying materials of similar geologic origin within a given locality. • Soil Color will change with moisture conditions. • Primary Color should be used (brown, gray, black, red...). • Soils with different shades or tints of basic colors are described using two basic colors (grayish brown, brownish gray, etc...). • Non-organic soil colors are associated with the presence, absence, or oxygenation of iron minerals. • Gray soil indicate that the surface particles have not reacted with oxygen. • Yellow and brown soils will become gray over time in anaerobic conditions.

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum • The soil color of the upper aerated profile will typically be brown to yellowish brown. • The soil color below the groundwater table will be typically more grayish. • A profile of clay soils typically go from brown near the surface and fade to gray with depth due to the lack of oxygen. • Sand colors are not typically affect by moisture. Standard set contain 322 colors

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum Primary Component • Primary material encountered. • Given a letter-number code designation example Gravel (A-1-a) Silt (A-4b) Clay (A-7-6)

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum Organics in Soils Except Peat: Describe organics by characteristics such as smell, texture, staining, color, or presence of organic material. 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. Gravel and Rock Fragments: Differentiate between gravel and rock fragments as follows: Gravel is rounded or sub-rounded pieces of rock exposed to either stream or glacial abrasion. Rock fragments are angular pieces of rock subjected to little or no abrasive action.

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum Supplementary Descriptive Terms: Use supplemental descriptive terms for additional information when appropriate, such as: well-graded, uniform, gap-graded, glacial till, alluvial, or residual. Use secondary descriptive terms such as: a description of foreign material, organic odor, fissures, voids or cavities, staining, or lenses. Denote isolated areas (such as lenses) with @ and depths!

Visual Classification Course for Geotechnical Logging of Soil and Rock Stratum Example #1: • Medium dense, brown coarse and fine sand (A-3a), some gravel, trace silt and clay, well-graded, wet. Example #2: • Very stiff, mottled brown and yellow silty clay (A-6b), some sand, little rock fragments, moist.

Ohio Department of Transportation