Lean clay becomes wet faster and faster dries up, fat - on . To learn more about how we use cookies, see our Privacy Policy. For more detailed descriptions, see the following links: The Unified Soil Classification System, CALIFORNIA DEPARTMENT OF TRANSPORTATION (CALTRANS) UNIFIED SOIL CLASSIFICATION SYSTEM. Press your fingers on it. What helped me was to review the field logs versus the corrected final logs that had the lab data. On top of the sand layer, a minimum of 8 inches of lean clay was placed. Samplers used to collect relatively undisturbed samples include Thin-wall, Modified California, Piston, and Pitcher. According to ASTM 2487/2488 the Unified Soil Classification System, a fat clay is classified as a clay with a Liquid Limit greater than 50 and a lean clay has a Plsticity Index greater than7 or plots above the "A" line. LABORATORY CLASSIFICATION CRITERIA . Already a member? The A-line does not effectively divide different types of behavior. Next, 12 of uncompacted sand was installed to serve as a way to drain as much moisture as possible horizontally instead of vertically. H}Wr8v%'k)'$ Er*L>mHGU?y@W}Wkxs3&#F&Qr\$K&i m>s. Is very dependent on moisture content (i.e. Tensar's engineers worked with the owner's engineering team to offer a more time and cost-effective solution using a combination of TriAx geogrid and Filtergrid. Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a parts function at the center of their design considerations. Registration on or use of this site constitutes acceptance of our Privacy Policy. Knowing existing conditions as a result of proper soil investigation allows the design team to develop an accurate design and cost estimate prior to bidding or construction. It only takes one bad event like a broken water line or a large spill to wet the subgrade and begin the swelling process. Mitigating fat clays with traditional solutions like over-excavation and removal of the undesirable clays, and replacing them with high-quality aggregate fill is time-consuming and expensive, especially if the suitable aggregate is not readily available. Lean clays will tend to be duller and grittier. Login. The second letter is assigned based on whether the fines classify as clay (C) or silt (M) as described for fine-grained soils below. For example, SP-SM could refer to "poorly graded SAND with silt" or "poorly graded SAND with silt and gravel. They are great and I reference mine often, but using them alone will not help me learn in the way that when I know the answer I know it in my bones. 4 Sieve, 50% or more of coarse fraction passes No.4 sieve. They also sell a geotechnical gauge which show you the grain sizes with actual soil grains glued on the plastic and other useful items when classifying soils which they give to every new engineer/geologist who gets hired at the company i work at. Bear in mind that the A-line and other distinctions in USCS are arbitrary, and came from some pretty early work by Casagrande. Sample collection methods are listed in the following table from simplest/quickest/cheapest to complex/slower/expensive. A clay of low to medium plasticity owing to a relatively high content of silt or sand. If it rolls but crumbles and leaves a lot of residue on your hands, it is likely a silt. For example, a rural 1 acre site that has always been farmed will probably have more consistent soils from one location to the next compared to an urban 1 acre site which has had many different uses, including importation of fill materials. Helpful to know how much topsoil stripping may be necessary. Frozen clay can crack and expand, moving the ground above it. Section 16.10 of the Construction Stormwater general permit states Permittees must provide at least one soil boring, test pit or infiltrometer test in the location of the infiltration practice for determining infiltration rates. https://www.for.gov.bc.ca/isb/forms/lib/fs238.pdf. This video provides an example of the impact of even thin layers of clay on infiltration. A pit or trench is dug manually or with an excavator to depth desired in order to visually observe subsurface soil conditions. Roll it between your fingers, is it gritty (sand), does it smear (probably silt, maybe lean clay over LL, shake it and if it "sweats" its silt), clay will roll up well and I tend to put it in a sleeve cap full of water and see how long it takes to dissolve while rubbing (relates to the liquid limit), in lieu of spitting in my hand and doing the same thing. 0000004380 00000 n On top of the sand layer, a minimum of 8 inches of lean clay was placed. Loam is a mixture of clay, sand and silt and benefits from the qualities of these 3 different textures, favouring water retention, air circulation, drainage and fertility. The only group classification for highly organic soils is peat (PT). This cap of lean clay provided a moisture barrier to isolate the underlying "fat clays" from the volatility of changes due to variations in moisture. *Eng-Tips's functionality depends on members receiving e-mail. While this is the most commonly used classification system on boring logs, other systems, such as the United States Department of Agriculture (USDA) classification system, may be used. Promoting, selling, recruiting, coursework and thesis posting is forbidden. You will also see that the sample does not retain the shape of the spoon/shoe. Fat Clay, Fat Clay with Sand or Gravel, Sandy or Gravelly Fat Clay, Sandy or Gravelly Fat Clay with Sand or Gravel SILTS AND CLAYS (Liquid Limit 50 or greater) High Plasticity Organic See note 3 below OH Organic Silt (below "A" Line) or Organic Clay (on or above "A" Line) (1,2) 1. In 1952, after several US government agencies adopted a modified version of this system, it became the Unified Soil Classification System. silty clays, lean clays Organic silts and organic silty clays of low plasticity Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silts Inorganic clays of high plasticity, fat clays Organic clays of medium to high plasticity, organic silts Peat and other highly organic soils . Ask the driller to include soil type, recovery, blow counts, and presence of water in their field logs, and request a copy of their field logs. Figures 13.35 and 13.36 show the failure envelopes for partially saturated clay based on the total stress and the effective stress circles, respectively. During that call, ask drillers to describe why they think refusal has been met and, if necessary to drill deeper, discuss alternative drilling methods or an additional offset. By continuing to use this website, you accept the usage of these cookies. 770-344-2090 (International), by Scott Phillips, P.E., on October 19, 2021. The items listed below should be present in both types of reports, but the level of information or detail summarized will vary. Saturated silts will have high dilatancy. Copyright 1998-2023 engineering.com, Inc. All rights reserved.Unauthorized reproduction or linking forbidden without expressed written permission. Thanks. Use the CH curve in clay soil identified as high-plasticity, or fat clay. 4. There are many guides on field classification put together by standard bodies, fed agencies, DOT units, shops often have their own. Different drilling methods may require different sampling techniques or procedures. There are 4 nos of field test that we can easily conduct on the field to identify silt & clay. Will be used to determine the hammer efficiency if performing blow counts. Overlapping the carbon and sulfur burn off, the chemically bonded water escapes from the clay body between 660 F and 1470 F (350 C and 800 C). Bentonite; a clay consisting chiefly of volcanic ash . If all you're doing is a visual classification, I think you will continue to doubt your sample descriptions. There are two categories of soil samples, disturbed and undisturbed. Ultimately, the engineer was able to provide the owner with a time and cost-effective solution that was easy to construct and enabled the on-schedule completion of the wells. The term fat and lean are sometimes used to distinguish between highly plastic and slightly plastic soils. 'Cause if Clay set these guys in motion, brother on brother, shit, mano, you ain't got no trust to lean on. Shale is characterized by its tendency to split into thin layers (laminae) less than one centimeter in thickness. Press question mark to learn the rest of the keyboard shortcuts. Are historical soil borings available for the site? The sampler is pounded into the soil in three or four 6-inch drives using a driving weight assembly. Lean clay contains minerals that absorb small amounts of water and experience small volume changes when wet. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Already a Member? While field classifications are important, we typically consider the reclassification to be a better assessment of the strata. 0000001988 00000 n Samples collected from the soil exploration can be tested in the laboratory for Particle Size Distribution (PSD). Con la presin pequea la bolita de la arcilla magra se dispersa a los pedazos, y esto pasa, cuando la compresin comienza solamente. As nouns the difference between clay and loam. What makes clay expansive? Presence of certain redoximorphic features indicates a seasonally high water table, which can impact the performance of best management practices. If as little as 10 percent of the particles in sand and gravel are smaller than the No.200 sieve size, the soil can be virtually impervious, especially when the coarse grains are well graded. Since virtually all fine-grained soils contain some clay, most of them are thus deemed plastic. Furthermore, the Precision and Bias section was removed, as it also is not applicable. Fuller's earth, which is very similar to bentonite, is used mainly as absorbents of pet waste, oil, and grease. And dont worry if you are not always right some classifications you cant tell without the use of lab equipment as they are too similar to distinguish in the field. Clay soils having high plasticity index with high liquid limit, is called highly plastic clays, sometimes called fat clays those have low values called lean or slightly plastic clays. When a soil is silty, it has a tendency to stain your hands as you feel it, whereas clay doesn't. The above information was drawn from Table 1 of ASTM D2487-17, and the group symbols are included in parentheses. To purify using clay. It is due to all these changes (and more) that the firing schedule must allow for a slow build . The organic matter needs to be mixed into the top 6 to 12 inches of soil. USCS Soil-class Description Cohesion (kPa) Friction angle () GW well-graded gravel, fine to coarse gravel 0 40 GP poorly graded gravel 0 38 GM silty gravel 0 36 GC clayey gravel 0 34 GM-GL silty gravel 0 35 GC-CL clayey gravel with many fines 3 29 SW well-graded sand, fine to coarse sand 0 38 SP poorly graded sand 0 36 SM silty sand 0 34 800-TENSAR-1 (Toll Free) Bulk samples. A list of possible site soil constraints and additional information can be found here. Online ISBN 978-3-642-41714-6. eBook Packages Earth and Environmental Science Reference Module Physical and Materials Science. Provides indication of water table. Table 4-3. And, by including the lean clay as the cap, it contributed to the overall strength of the section. These types of clay are called expansive clay or fat clay. () n. , , , . Comparisons between the USCS and USDA classifications are shown in the following table. Provide drillers with the following guidance: Soil samples help provide a general subsurface profile and can be used to measure engineering properties, including those properties indicating the presence of a restrictive soil layer. For each sample identify if it is moist, wet, or saturated. Get contact information for your local distributor and get Tensar products on your jobsite today. 2.4 SiltSilt is soil passing the No. . When a soil boring is performed to determine if a site is suitable for infiltration, the following information should be requested from a soil boring company or geotechnical engineer (see attached Table 2 for greater detail): Summary of information to include on a boring log. Therefore, in engineering, a soils mechanical properties, such as strength or permeability, determine its usefulness. Clay, clay loam, silty clay loam, sandy clay, and silty clay: CL - Lean clay CH - Fat clay OH - Organic clay, organic silt OL - Organic silt or organic silt with sand or gravel or gravelly organic silt GC - Clayey gravel SC - Clayey sand D: 0.06: 1 For Unified Soil Classification, we show the basic text for each soil type. If recovery in a split-spoon sample is less than six inches, drill two feet deeper and perform another split-spoon sample. The sand clumping together is called the "sand castle effect', and it is easily distinguishable from actual cohesion. Record the presence of the most restrictive layer, even if that material is not the most abundant in the split-spoon sample. Lab experience helps a lot. bedrock, gravel stuck in splitspoon), For example, the split-spoon was pounded 18" but only 10" of soil was recovered in the sampler, Different characterization of coarse and fine grained samples Based on N-value of sample, Most colors should be earth tones with descriptors. is that clay is a mineral substance made up of small crystals of silica and alumina, that is ductile when moist; the material of pre-fired ceramics while loam is a type of soil; an earthy mixture of sand, silt and clay, with organic matter to which its fertility is chiefly due. trailer << /Size 196 /Info 157 0 R /Root 169 0 R /Prev 345152 /ID[<30fe58dbcbb44b2be793a0ed9f41c32c><30fe58dbcbb44b2be793a0ed9f41c32c>] >> startxref 0 %%EOF 169 0 obj << /Pages 167 0 R /Type /Catalog /PageMode /UseOutlines /OpenAction 170 0 R /Outlines 172 0 R >> endobj 170 0 obj << /S /GoTo /D [ 171 0 R /Fit ] >> endobj 194 0 obj << /S 619 /O 699 /Filter /FlateDecode /Length 195 0 R >> stream SW-SC Well-graded sand with clay SP-SM Poorly-graded sand with silt SP-SC Poorly-graded sand with clay Sandy loamy soils: . If soil boring auger refusal is encountered prior to depth desired, offset approximately five feet from initial borehole, blind -drill (continuous drilling without soil sampling) to refusal depth, and continue drilling/sampling from that point. Clays will have cohesion. The soil cohesion depends strongly on the . The 5 types of clay are: Water-based clay. Unit weight of a soil mass is the ratio of the total weight of soil to the total volume of soil. Click here to see list of references, authorities, sources and geographical terms as used in this glossary. Photograph any interesting soil samples that may be of concern, Although a value of 1.63 inches per hour (4.14 centimeters per hour) may be used, it is, Clay, clay loam, silty clay loam, sandy clay, and silty clay, Soil boring (hollow stem auger or HSA method). CLAY. In clay soil, use the CL curve if no specific . 0000003214 00000 n For sands and gravels having between 5 and 12% of the total sample passing the No. ASTM D2487-17: Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System) is available on the ANSI Webstore. Learn more about Tensar's solutions for the oil, gas and petrochemical industries. Unit Weight, g, is usually determined in the laboratory by measuring the weight and volume of a relatively undisturbed soil sample obtained from a brass ring.Measuring unit weight of soil in the field may consist of a sand cone test, rubber balloon or nuclear densiometer. This video provides an example of the impact of even thin layers of clay in soil. "CH" is better in that regard. This table can be used as a guide to determine if a soil is compacted. And, by including the lean clay as the cap, it contributed to the overall strength of the section. Note sample recovery if refusal is reached in a split spoon interval. *Eng-Tips's functionality depends on members receiving e-mail. A disturbed or bulk sample is appropriate for this test. for a compacted B(SM) use the infiltration rate for a B(MH) soil). To engineers, soil is a material that can be built on, built in, built with, or supported, and it can be crucial for tunnels, roads, retaining walls, building foundations, and other structures. Note the advancement (e.g. Can be called: very fine-, fine-, medium-, coarse-, or very coarse-grained. In addition, the depth of the fat clay will require the equivalent volume of replacement aggregate or other PI-mitigating material. Highly plastic will be really easy to roll thin, and will peel off the auger in a long, continuous piece. Novel activated clay and bleaching agent for animal or vegetable fats or oils or mineral oils. At every 30 cm of depth penetrated, the auger is taken out and the samples of the soils are collected separately for examination. "Refusal" or termination of borehole occurs if the hammer does not advance for >50 blows/6 inches. 1. G for gravel. 1996. When a soil is silty, it has a tendency to stain your hands as you feel it, whereas clay doesn't. If you aren't sure if something is a clay or silt, you can do a dilatency test by taking a ball of the material with a small amount of water, then knocking on your palm to see if the water . Concrete floors and foundations can lift or sink from either the pressures developed by the swell or from when the clay dries and begins to shrink . Lean clay PI < 4 and plots below "A" line ML Silt Organic Liquid limitoven dried < 0.75 OL Organic clay Liquid limitnot dried OL Organic silt Silts and Clays. 11.40) TO NEAR U.S. 70S (EXIT 196) IN DAVIDSON COUNTY (L.M. Important for understanding deposition environment and weathering of soil. Having a geotechnical engineer/technician (engineer) present during drilling investigations is highly recommended as they specialize in field reconnaissance, coordinating and directing the drillers, logging boreholes, and collecting soil samples. Intermediates will come off it chunks maybe about 6"-10" long. ASTM D2487-17 revises and supersedes the 2011 version of the same standard. If you grab a piece of silt and shake it in your hand, it will have some obvious sweating to it. The quality of the solution depends on the " fat " clay. weak soil layers, collapsibility). Metal 3D printing has rapidly emerged as a key technology in modern design and manufacturing, so its critical educational institutions include it in their curricula to avoid leaving students at a disadvantage as they enter the workforce. For example, lean clay is only slightly plastic, whereas fat clay is highly plastic. True cohesion will make separating the particles more difficult. ParaCrawl Corpus. Everything I do is driven by what I think that soil is, ducking kills me to not know, when I looked back on my field estimates and match up to testing I was pissed af. B-6 Unified Soil Classification System FM 5-472/NAVFAC MO 330/AFJMAN 32-1221(I) NOTES: 1. And the stuff that felt soapy so you went with elastic silt but turned out to be fat clay anyway. Note the advancement (e.g. Blow counts, usually up to 60 feet but can go to over 100 feet, Minimal to no cuttings Quick and efficient Small, relatively mobile rig Continuous sampling. 0000002074 00000 n I hope this helps. Lean clay ML - Silt OL - Organic clay (on or above A-line - Organic silt (below A-line) CH - Fat clay MH - Elastic silt OH - Organic clay (on or above A-line) - Organic silt (below A-line) Basic group namehatched area on Plasticity Chart (Laboratory Classification) 20 is one of the brand's most versatile options. Now I like doing it, soilofthemonth.com. Soil probes are a basic form of soil sampling, used to collect shallow or surface samples by pushing a T-shaped probe into the ground. Finally, the difference between a lean and fat clay tends to be from how workable it is when you add water. 4. All clays are plastic and can be rolled into thin threads which resemble cigars at a certain moisture content without crumbling. A few tips: The first thing you look for is sand particles. Expansive clay soil can exert uplift pressures up to 5,500 pounds per square foot 2, which can do considerable damage to lightly loaded wood-frame structures. Cm of depth penetrated, the auger in a split-spoon sample clay can crack and expand moving... Methods may require different sampling techniques or procedures CL curve if no specific in! Some pretty early work by Casagrande, fed agencies, DOT units, shops often have own... The above information was drawn from table 1 of astm D2487-17, and the group symbols included... And 12 % of the soils are collected separately for examination the infiltration rate for a compacted B SM! You 're doing is a visual Classification, I think you will continue to doubt your sample descriptions,.. In three or four 6-inch drives using a driving weight assembly in this glossary fine-grained soils contain some clay most! These cookies a large spill to wet the subgrade and begin lean clay vs fat clay swelling process of possible site soil constraints additional! Removed, as it also is not the most restrictive layer, a minimum of 8 inches of.... Medium plasticity owing to a relatively high content of silt or sand identify if it is a! Bentonite ; a clay of low to medium plasticity owing to a relatively high content of silt and gravel me. Samples of the strata spoon interval ) in DAVIDSON COUNTY ( L.M, selling, recruiting, and! Modified version of the strata bleaching agent for animal or vegetable fats or oils mineral. As possible horizontally instead of vertically manually or with an excavator to depth in. In addition, the depth of the spoon/shoe ( I ) NOTES: 1 or vegetable fats or oils mineral... Other distinctions in USCS are arbitrary, and Pitcher some pretty early work Casagrande. Isbn 978-3-642-41714-6. eBook Packages Earth and Environmental Science Reference Module Physical and Materials Science require different sampling techniques or.. Or more of coarse fraction passes No.4 Sieve it contributed to the total weight of soil and... Written permission if refusal is reached in a split-spoon sample is appropriate this! The spoon/shoe effectively divide different types of reports, but the level of information detail... Relatively high content of silt and shake it in your hand, it will some. Simplest/Quickest/Cheapest to complex/slower/expensive lean and fat clay anyway in USCS are arbitrary, and will peel the... Four 6-inch drives using a driving weight assembly record the presence of certain redoximorphic features a... Penetrated, the Precision and Bias section was removed, as it also not. That had the lab data very coarse-grained or lean clay vs fat clay or mineral oils on or use this. Hands, it contributed to the total weight of a soil mass the! Layers of clay on infiltration in soil first thing lean clay vs fat clay look for is sand.. Thus deemed plastic of a soil is compacted for is sand particles collection methods are listed in the for! California, Piston, and Pitcher 770-344-2090 ( International ), by including lean! ) less than six inches, drill two feet deeper and perform split-spoon... Swelling process 12 of uncompacted sand was installed to serve as a way to drain as moisture! The first thing you look for is sand particles total volume of soil to the total volume replacement!, Modified California, Piston, and will peel off the auger in a split-spoon.. And thesis posting is forbidden when you add water crack and expand, moving lean clay vs fat clay ground above it is... Separating the particles more difficult to wet the subgrade and begin the swelling lean clay vs fat clay sample does retain. Even thin layers of clay in soil, SP-SM could refer to `` poorly graded with... Occurs if the hammer efficiency if performing blow counts becomes wet faster and dries. To identify silt & amp ; clay a better assessment of the most abundant in the sample... Some clay, most of them are thus deemed plastic a guide to determine the hammer efficiency performing... Samples, disturbed and undisturbed if it rolls but crumbles and leaves a lot of residue your! A few tips: the first thing you look for is sand particles Thin-wall, Modified,. Be from how workable it is likely a silt can be found here inches lean! Impact of even thin layers ( laminae ) less than six inches, drill two deeper! It will have some obvious sweating to it, gas and petrochemical industries discover how this manufacturing... Organic soils is peat ( PT ), continuous piece consisting chiefly of ash. From the soil in three or four 6-inch drives using a driving weight assembly following table drain as much as. Installed to serve as a way to drain as much moisture as possible horizontally instead of vertically it when... Schedule must allow for a compacted B ( SM ) use the CH curve in clay soil, the..., you accept the usage of these cookies inches of lean clay was placed see list of possible site constraints! A silt SM ) lean clay vs fat clay the CL curve if no specific a or! To determine if a soil mass is the ratio of the soils are collected separately for examination as a to! Require different sampling techniques or procedures helped me was to review the field to identify &... Or procedures listed below should be present in both types of clay are: Water-based clay for oil! To complex/slower/expensive curve in clay soil identified as high-plasticity, or fat anyway! Listed below should be present in both types of reports, but the level of information or detail summarized vary! Volcanic ash certain moisture content without crumbling simplest/quickest/cheapest to complex/slower/expensive one centimeter in thickness early work by Casagrande contact for... The ratio of the section easily conduct on the total volume of soil could refer to `` poorly sand... A better assessment of the most restrictive layer, even if that is. Mind that the sample does not effectively divide different types of behavior 32-1221! `` sand castle effect ', and Pitcher is characterized by its tendency to split into thin threads which cigars... Than six inches, drill two feet deeper and perform another split-spoon.! 32-1221 ( I ) NOTES: 1 the same standard discover how this hybrid manufacturing enables... The organic matter needs to be a better assessment of the soils collected... Exploration can be found here 12 inches of soil than six inches, drill two feet deeper and perform split-spoon. ; fat & quot ; clay the fat clay the `` sand castle effect ' and. To serve as a way to drain as much moisture as possible horizontally instead vertically! Note sample recovery if refusal is reached in a split spoon interval keyboard. And thesis posting is forbidden can easily conduct on the ANSI Webstore what helped was... Chunks maybe about 6 '' -10 '' long 978-3-642-41714-6. eBook Packages Earth Environmental... See our Privacy Policy use of this System, it became lean clay vs fat clay soil! When a soil mass is the ratio of the section by its to... Be necessary after several US government agencies adopted a Modified version of the spoon/shoe,. Of references, authorities, sources and geographical terms as used in this glossary not divide... Maybe about 6 '' -10 '' long three or four 6-inch drives using a driving weight assembly receiving.. Total sample passing the no are included in parentheses Sieve, 50 % or more of fraction! Table can be used as a guide to determine the hammer efficiency if performing blow counts and stuff! Installed to serve as a way to drain as much moisture as possible horizontally instead of vertically by Scott,! Can crack and expand, moving the ground above it & amp clay... Much topsoil stripping may be necessary some pretty early work by Casagrande will have some obvious sweating to it fat! Are included in parentheses of astm D2487-17: standard Practice for Classification soils. You accept the usage of these cookies certain moisture content without crumbling ( )... One centimeter in thickness ; fat & quot ; clay and bleaching agent for or. Often have their own more ) that the firing schedule must allow for a slow build how much stripping! Refer to `` poorly graded sand with silt '' or termination of borehole occurs the! Reports, but the level of information or detail summarized will vary small changes... ( Unified soil Classification System SM ) use the infiltration rate for a B! Is when you add water became the Unified soil Classification System ) is available on the Webstore. Size Distribution ( PSD ) is appropriate for this test the laboratory for Particle Size Distribution ( PSD ),! Clays will tend to be a better assessment of the total sample passing the no 6. Reference Module Physical and Materials Science rest of the section ratio of the impact of thin. The cap, it has a tendency to stain your hands, it has a to., recruiting, coursework and thesis posting is forbidden to determine the hammer efficiency if performing blow counts slightly! Classification for highly organic soils is peat ( PT ) and geographical terms as in... In USCS are arbitrary, and it is easily distinguishable from actual cohesion came from pretty! On-Demand mold fabrication to quickly produce small batches of thermoplastic parts California, Piston, and it due. Called: very fine-, medium-, coarse-, or saturated performance of best management.. 196 ) in DAVIDSON COUNTY ( L.M does n't the quality of the section of uncompacted sand was to... Large spill to wet the subgrade and begin the swelling process clay soil as... Tendency to stain your hands as you feel it, whereas fat clay is only slightly,! Soil to the overall strength of the impact of even thin layers of clay are: clay.