Forging new generations of engineers

Forging new generations of engineers
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Forging new generations of engineers Project Lead The Way, Inc. Copyright 2007

SOILS Civil Engineering & ArchitectureTM
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading SOILS Civil Engineering & ArchitectureTM This presentation is based on the information in Unit 4, Lesson 4.5, Activity Soil Testing. Unit 4 - Lesson Activity 4.5.1 Soil Testing Project Lead The Way, Inc. Copyright 2007

Soil Testing

Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Introduction Prior to developing a property for a commercial endeavor, a designer needs to investigate the soil conditions at the site. There is no construction material that has both the physical and engineering properties which are more variable than soil. Therefore it is highly desirable to have some information regarding both the surface and subsurface soil conditions. Before we can consider designing the building structure or determine the site grading, we need to know the type of soils that are present in the area in which we would like to build. Once we have the information about the type of soil that is present , and we know the properties of that particular soil type , we can begin to make some preliminary design considerations Project Lead The Way, Inc. Copyright 2007

Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Soil – What is it? Soils rarely exists as separate components such as sand or gravel. Soils contain various particle sizes of gravel, sand, silt and clay and each contributes to the characteristics of the soil. Soils are comprised of a unique combination gravel, sand, silt and clay. Soils contain a variety of particle sizes with varying portions of gravel, sand, silt and clay. Each component contributes to the engineering characteristics of the material. Project Lead The Way, Inc. Copyright 2007

Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Why Test the Soil??? The knowledge gained from soil testing allows the engineer to make estimates for: Bearing Capacity of the soil Settlements of Foundation ( amount and rate) Earth Pressure – both lateral and vertical Drainage These characteristics determine how certain soils behave as a construction material. Soil Testing allows the the engineer to determine how the soils will behave as a construction material. Soils classification determines the various physical properties of the soil and provides a correlation to the engineering properties. The soils underneath a building will influence the type and size of the building foundation. In turn, the foundation may influence the type of building structure that will be erected. The soils conditions can also effect the construction costs. The bearing capacity is ability of the soil to carry the load with out any failure within the soil. It also refereed to to as the stability of the soil. The load carrying capacity of the soil can vary with the strength of the soils and the method and magnitude in which the loads are applied. The amount and rate of settlement of the foundation can be estimated for a known soil type and the building can be design to accommodate a certain amount of settlement Earth Pressure refers to the pressure that the earth transmits to the building. The drainage qualities of the soils can effect the pressure on the foundation either with too much water or excessive water pressure. Project Lead The Way, Inc. Copyright 2007

What is Needed to Determine Soil Properties
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading What is Needed to Determine Soil Properties Site Plan Site Profile (Contour Map) Geological Information (USGS Maps) Soils Sample Data(obtained through soils analysis/testing) In order for the engineer to determine the type of soils and the building characteristics of that soil, a site plan, a contour map or site profile and a geological survey map for the area are all needed, in addition to the Soils Property information that will be obtained during testing. This information allows the engineer to determine the soil properties and to make a decision as to the type of foundation to use. This information maybe relatively easy to obtain for a one to two story building in which the building loads are small and the foundations are shallow, as only a three or four shallow soil samples are needed. As the height of the building increases and the building loads increase, the amount of soils sampling information and sampling also increases. Project Lead The Way, Inc. Copyright 2007

Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Factors to be taken into consideration when determining the type of the building foundations: Function of the structure Loads from the structure Bearing capacity of foundation material Total and differential settlement of foundation Uplift forces acting on the foundation Costs There are several factors that need to be considered when determining the type of building foundation you will need. The soil type and condition is a major factor in the engineering decision. The function of the structure refers to the type of building, such as educational, small commercial or heavy industrial building. Each type of building will have vastly different building loads due to the building materials selected and the live loads imposed on the structure. The bearing capacity of the foundation material refers to the strength of the soil, which is determined by investigated soils techniques. The settlement of a structure can be a result of a under designed foundations system, poor soil conditions or unknown or undetected soils conditions. Uplift forces refer to the imposed loads from the soil and groundwater acting on the foundation and can cause the foundation to be pushed up yeilding unwanted cracks in the foundation or failure. Costs of a foundation are dependent on the type of foundation system used and the type of soils at the site. If the soils analysis results do not accurately depict the soil , the foundations costs could become very costly and the foundation system become more complex or the foundation could have been over designed when it was not required. Project Lead The Way, Inc. Copyright 2007

Local or State Building Codes Uniform Building Code (UBC)
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading The Soil Bearing Capacity needs to be determined before a foundation system can be designed. This can be determined by: Local or State Building Codes Uniform Building Code (UBC) Soil testing/analysis Site inspection and simple soil testing methods ( surface soils- top 1 foot) Soil borings taken at proposed foundation locations (subsurface soils) Presumptive Bearing Capacity The soil bearing capacity is determined by the geotechnical engineer, it can be based on governing building codes, on soil analysis and testing or by past experience with similar soils in the regional area. Geotechnical Engineers accumulate information on the successes of their other designs in the area and use these a a basis for future designs. It is easy to see that “engineering judgment “ can play a role in the analysis of the soil. Engineering judgment should not be confused with “best guess”. When engineering judgment is used a soil bearing capacity can be assumed based on some of this information, this is known as the presumptive bearing capacity of the soil. The presumptive soil bearing capacity is typically a lower bearing capacity value than could be determined through soils testing. Project Lead The Way, Inc. Copyright 2007

Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Sample Soils Soil testing must be done on soil samples that truly represent the the soil at the site. Soil sample about 1’-2’ below surface Boring samples are taken at various locations and depths below the surface (subsurface) for deep foundations When taking soils samples, the location and the depth of the soils sample should be representative of the soils at the site. Soils samples are typically taken where the building foundation will be located and where the septic system will be located. Other locations can be selected to confirm the soils results. Keep in mind that the soils throughout the site may or may not be uniform. There could be outcroppings of rock or other soils types that you did not locate within the site. When this happens, the engineer must be able to determine if is these samples are representative or the site or should additional soil testing be required. Project Lead The Way, Inc. Copyright 2007

Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Soils Testing Unified Soils Classification System is a method for for identifying and grouping soils. It was first developed by Casagrande for military construction of airfields. Many soils can be grouped visually with the USGS with additional tests for grain size and plasticity required to accurately classify the soil. The Unified Soils Classification System is a rapid method for for identifying and grouping soils. It was first developed by Casagrande for military construction of airfields . Many soils can be grouped visually with the USGS with additional tests for grain size and plasticity required to accurately classify the soil. Project Lead The Way, Inc. Copyright 2007

Unified Soil Classification System
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Unified Soil Classification System The Unified Soil Classification System is a rapid method used to determine Simple Grain Size Analysis and categorizes the soil as either : -Coarse-Grained Soils -Fine Grained Soils -Highly Organic Soils Only particles sizes smaller than 3” are considered in the USC System We are going to look at soil testing methods that provide information about the size of the soil particles, the percentage of various sizes of soils particles, and the characteristics of the very fine grains within the soil sample. The Unified Soil Classification System is based on the results of a test that determines grain size distribution of the soil sample. Only particles sizes smaller than 3” are considered in the USC System. This system is based on the characteristics of the soils that indicates how the soil will be have as a construction material. There are many indicators and descriptors for soil. In the USCS, all soils are placed into one of three major categories. They are Coarse-grained. Fine-grained. Highly organic. Project Lead The Way, Inc. Copyright 2007

Coarse vs. Fine Grained Soils
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Coarse vs. Fine Grained Soils Many soils can be grouped visually with the USGS and additional tests for grain size and plasticity are required to accurately classify the soil Coarse-Grained soils described by grain size Fine-Grained Soils described on the basis of their plasticity Many soils can be grouped visually with the USGS and additional tests for grain size and plasticity are required to accurately classify the soil The Coarse-Grained soils are described by grain size The Fine-Grained Soils are described y on the basis of their plasticity Project Lead The Way, Inc. Copyright 2007

Sieve Sizes Gravels range from 3” down to the size of peas
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Sieve Sizes Gravels range from 3” down to the size of peas Soils are usually a mixture of gravel, sand, silt and clay. Gravels range from about 3” down to the size of peas. Sands start just below this size and decrease until the individual grains are just distinguishable by the naked eye. The eye can normally see individual grains about 0.07 millimeter in size, or about the size of the Number 200 sieve. Silt and clay particles, which are smaller than sands, are indistinguishable as individual particles. In our testing, we are using the Number 4 sieve which has a openings of 1/4” and the Number 40 sieve which has an openings similar to that of a window screen. We will do additional testing to determine the silt and clay content of the fine particles that pass through the Number 40 screen., Silt and clay can pass through the #200 sieve Project Lead The Way, Inc. Copyright 2007

Sieves #40 sieve ( similar to window screen)
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Sieves #40 sieve ( similar to window screen) #4 sieve ( ¼” squares, similar to hardware cloth) Project Lead The Way, Inc. Copyright 2007

Grain Size (Gradation)
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Grain Size (Gradation) Gravel Sand Boulder Cobbles Silt & Coarse Fine Coarse Medium Fine Comparable Size: >12” 3”–12” ¾”–3” #4 - ¾” #10 - #4 #40-#10 #200-#40 <#200 Clay There are many different types of soils, such as rock, gravel, sand, clay and silt. The soils that we encounter are a heterogeneous mixture of these basic types. The gradation of the soil particles ranges from boulders which are over 12” in diameter to silt and clay particles that are so small that they can not be individually distinguished by the naked eye. Gravels are separated into either coarse gravel or fine gravel with the 3/4-inch sieve as the dividing line. Sands are either coarse, medium, or fine with the No. 10 and No. 40 sieves, respectively . NOTE: Particles finer than fine sand ( #200 sieve) can not be seen by the naked eye at a distance of 8 inches Project Lead The Way, Inc. Copyright 2007

Gravel Identification
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Gravel Identification Coarse Gravel from 3” to ¾”, a comparable size – Plum or Lemon Coarse Gravel from 3” to ¾”, samples that were retained the #4 Fine Gravel from #4 to 10 , samples that were retained on both the #4 and # 10 sieves Fine Gravel from #4 to ¾”, a comparable size –Grape or Pea Project Lead The Way, Inc. Copyright 2007

Gravel Size Fine gravel Coarse gravel
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Gravel Size Coarse gravel Fine gravel Coarse Gravel from 3” to ¾”, samples that were retained the #4 Fine Gravel from #4 to 10 , samples that were retained on both the #4 and # 10 sieves Project Lead The Way, Inc. Copyright 2007

Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Sand Identification Coarse Sand from #4 to #10, a comparable size - Rocksalt Medium Sand from #10 to #40, a comparable size - Sugar Coarse Sand from # 4 to #10 , samples that were retained on both the #4 and # 10 sieves Medium Sand from #10 to #40 , samples that were retained on both the #4 and # 10 sieves Project Lead The Way, Inc. Copyright 2007

Sand Size Medium sand Coarse sand
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Sand Size Coarse sand Medium sand Coarse Sand equivalent in size to rocksalt. Medium Sand equivalent in size to sugar Project Lead The Way, Inc. Copyright 2007

Graded Soils Uniformly-soil particles are nearly the same size
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Graded Soils Soils can be defined by how the particle sizes are distributed within the soils sample. Well-Graded Soils-have a good representation of all particle sizes from the largest to smallest Poorly-Graded Soils- two types Uniformly-soil particles are nearly the same size Gap-Graded- contains both large and small particles but the graduation continuity is broken by the absence of some particle sizes Soils are described by their gradation characteristics. A Well-Graded Soil is defined as having a good representation of all particle sizes from the largest to the smallest. Poorly-Graded Soils are divided into two types. A uniformly graded soil consists primarily of particles of nearly the same size. A gap-graded soil contains both large and small particles, but the gradation continuity is broken by the absence of some particle sizes. Project Lead The Way, Inc. Copyright 2007

Clean vs. Dirty Graded Soils for Gravel and Sand
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Clean vs. Dirty Graded Soils for Gravel and Sand If a soil is identified as being “Clean” it contains little or no fines (<5%) If a soil is identified as being “Dirty” it contains an appreciable amount of fines ( >12%) Silty fines Clayey A gravel or Sand soil type can be classified as a “clean” or “dirty” depending on the percentage of fines within the soil sample. If a soil is identified as being “Clean” it contains little or no fines (<5%) If a soil is identified as being “Dirty” it contains an appreciable amount of fines ( >12%) Silty fines Clayey Project Lead The Way, Inc. Copyright 2007

Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Soil Designations The USCS divides soils that have been classified into the major soil categories by letter symbols, such as: S for sand G for gravel M for silt C for clay O for organic Pt for peat The USCS divides soils that have been classified into the major soil categories by letter symbols, such as: S for sand G for gravel M for silt C for clay O for organic Pt for peat Project Lead The Way, Inc. Copyright 2007

Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Grain Shape When examining samples for grain sizes, the shape of the visible particles can be determined. Sharp edges and flat surfaces indicate an angular shape; smooth, curved surfaces indicate a rounded shape. Particles may not be completely angular or completely rounded. These particles are called sub-angular or sub-rounded, depending on which shape predominates. “Platy” is the name given those particles which have one dimension relatively small compared to the other two. Clays generally fall into this category. Project Lead The Way, Inc. Copyright 2007

Soil Color Color can aid in distinguishing soils types
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Soil Color Color can aid in distinguishing soils types Can vary with moisture content May indicate the presence of certain chemical or impurities Dark brown /black may indicate organic material Gray, olive green indicate inorganic soils Red or yellow may indicate iron oxides Gray-blue or gray-yellow indicates poor drainage White to pink may indicate considerable silica, calcium carbonate, or aluminum compounds. Color helps in distinguishing between soil types and, with experience, aids in identifying the particular soil type. Color may also indicate the presence of certain chemicals or impurities. Color often varies with the soil's moisture content. Colors in general become darker as the moisture content increases and lighter as the soil dries. Some fine-grained soil with dark, drab shades of brown or gray (including almost black) contain organic colloidal matter. In contrast, clean, bright shades of gray, olive green, brown, red, yellow, and white are associated with inorganic soils. Gray-blue or gray-and-yellow mottled colors frequently result from poor drainage. Red, yellow, and yellowish-brown colors result from the presence of iron oxides. White to pink may indicate considerable silica, calcium carbonate, or aluminum compounds. Project Lead The Way, Inc. Copyright 2007

Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Plasticity Plasticity of the soils refers to the varying water content on the consistency of the soil in fine-grained soils. This system is sometimes referred to as the ATTERBERG LIMITS, named after the Swedish scientist who developed this test. Plastic Limit-lowest moisture content at which soils can be rolled into 1/8” dia.thread with out breaking Liquid Limit- minimum moisture content at which soil will flow when a small shear or cutting force is applied The Plasticity of the soil describe the plasticity of the soil based on effect of varying water content on the of fine-grained soils. The Plastic Limit is referred to lowest moisture content at which soils can be rolled into 1/8” dia.thread with out breaking The Liquid Limit is the minimum moisture content at which soil will flow when a small shear or cutting force is applied. These mean little unless they are used as indexec to the significant properties of the soil. Project Lead The Way, Inc. Copyright 2007

These letters are then used in combination to
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Soils Groups Soil Type Gradation Liquid Limit Gravel- G Sand-S Silt-M Clay-C Organic O Peat- Pt Well Graded- W Poorly Graded - P LL over 50- H LL under 50 -L The letter symbols are derived from the soil fractions of Gravel, Sand, Silt, Clay, Organic or Peat, the relative gradation of the soils particles and the value of the Liquid Limit. These letters are then used in combination to form the soils groups. These letters are then used in combination to form the soils groups Project Lead The Way, Inc. Copyright 2007

Determining the Silt or Clay Characteristics of Fine Grained Soil
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Determining the Silt or Clay Characteristics of Fine Grained Soil In addition to the Sieve Analysis the following tests will be done to determine of the Fine Grained soils Dry Strength- crushing characteristics Dilatancy- reaction to shaking Toughness- consistency near plastic limit In addition to the Sieve Analysis, the following soil tests that will determine the characteristics of the Fine Grained Silt or Clay are : Dry Strength- crushing characteristics Dilatancy- reaction to shaking Toughness- consistency near plastic limit Project Lead The Way, Inc. Copyright 2007

Unified Soil Classification System
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Unified Soil Classification System Start here The major divisions are Coarse Grained Soils, Fine Grained Soils and Highly Organic Silt. Starting with how much of the soil sample( by weight) is retained on the No. 200 Sieve, one can determine if it is a Coarse Grained Soils, a Gravel or Sand. If more than 50% of the soil particles pass through the No. 200 sieve, then the sample is a Fine grained Sand. Coarse-grained soils are defined as those in which at least half the material is retained on a No. 200 sieve. Project Lead The Way, Inc. Copyright 2007

Equipment for Testing Sample of soil about the size of a coffee can and collected below the top soil horizon (about 1 to 2 feet). 2 mason jars with tops 5 gallon pail Water Mixing bowl A 2’ x 2’ metal pan and rubber mallet Sieve collection, ASTM No 4 and ASTM No. 40Bottom sieve pan and cover Triple-beam balance or Digital Scale

USCS SYSTEM SEIVE ANALYSIS
Testing USCS SYSTEM SEIVE ANALYSIS

Weigh mason jars for later use
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Weigh each sieve separately Weigh each sieve individually, the pan and mason jar without the lid for later use. Remember we are using Number 40 and Number 4 sieves. Weigh mason jars for later use Project Lead The Way, Inc. Copyright 2007

Soils Sampling Take a representative soil sample from the property
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Soils Sampling Take a representative soil sample from the property A shovelful or coffee can of soil should be enough In taking a representative soil sample , we presume that it is representative of the soil in other locations of the property. Soil it not a composition of sand, gravel, silt and clay and is not homogeneous material, therefore,the location in which the soil is taken from should be in areas in which the building foundation will be located. A shovelful or coffee can of soil should be enough to complete the soils analysis. Project Lead The Way, Inc. Copyright 2007

Soil sample should be dry Pulverize the soil with a rubber mallet
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Soil sample should be dry Pulverize the soil with a rubber mallet The soil sample should be dry, preferably dried under low heat, less than 200⁰F for a few hours. If that is not possible, let the soil dry inside for several days. Pulverize the soil either with your fingers or a rubber mallet.. Be sure that all small and large clumps are completely broken apart. Remember that the sample should not contain rocks greater than 3 inches in diameter. Project Lead The Way, Inc. Copyright 2007

Continue to Pulverize the soil with your hands
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Continue to Pulverize the soil with your hands Be sure that all small and large clumps are completely broken apart. Continue to Pulverize the soil with your hands. Be sure that all small and large clumps are completely broken apart. Project Lead The Way, Inc. Copyright 2007

Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Stack sieves with Number 4 on top, then the Number 40 sieve below that, and then finally the bottom pan. Stack sieves with Number 4 on top, then the Number 40 sieve below that, and then finally the bottom pan. Note: the amount of soil put into the top sieve- shovelful of soil should be enough Project Lead The Way, Inc. Copyright 2007

Place soil in Number 4 sieve, place cover on top and shake vigorously.
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Place soil in Number 4 sieve, place cover on top and shake vigorously. Place soil in No 4 sieve, place cover on top and shake vigorously. Project Lead The Way, Inc. Copyright 2007

Shaking the Soil Sieves Shake with up and downward motion
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Shaking the Soil Sieves Shake with up and downward motion or / and Shake with side to and side motion Shake vigorously. Shaking the soils Sieves. You can shake the sieves with an up and downward motion and also use a side to side shaking motion. The goal is to separate the soils into the two sieves and the pan for fines. Do not shake the sample so hard that the lid falls off or you drop the pans , otherwise you will have to start over. Pull the cover off of the No 4 sieve and inspect contents to be sure that small dirt clumps do NOT exist on the No. 4 sieve. Manually break up small dirt clumps and shake again. Project Lead The Way, Inc. Copyright 2007

Weighing of each Sieve with Sample Particles
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Weighing of each Sieve with Sample Particles Weigh the sample material and the sieve. Subtract the weight of the sieve to obtain weight of soil. In this case , the weight of the particles is the Gravel fraction in the soil sample Do this for each sieve. Weigh the sample material and the sieve. Record and subtract the weight of the No 4 sieve only (i.e., without the soil sample). The difference is the GRAVEL fraction in the soil sample. Record and subtract the weight of the No 40 sieve only (i.e., without the soil sample). The difference is the coarse and medium grained SAND fraction in the soil sample. Weigh the bottom pan and its contents. Record and subtract the weight of the empty pan. The difference is the fine SAND, SILT, and CLAY fraction of the soil sample. Project Lead The Way, Inc. Copyright 2007

Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading #4 Sieve with Gravel By weighing the sample retained on the sieve, we can see how much of the sample, by weight was retained. Then we can compare it to the USCS chart and determine whether it is Coarse or Fine Grained Soil. Project Lead The Way, Inc. Copyright 2007

Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading #4O Sieve with Sand Record and subtract the weight of the No.40 sieve only (i.e., without the soil sample). The difference is the coarse and medium grained SAND fraction in the soil sample. Record and subtract the weight of the Number 40 sieve only (i.e., without the soil sample). The difference is the coarse and medium grained SAND fraction in the soil sample. Project Lead The Way, Inc. Copyright 2007

Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Bottom pan with Fines Weigh the bottom pan and its contents. Record and subtract the weight of the empty pan. The difference is the fine SAND, SILT, and CLAY fraction of the soil sample. Weigh the bottom pan and its contents. Record and subtract the weight of the empty pan. The difference is the fine SAND, SILT, and CLAY fraction of the soil sample. Project Lead The Way, Inc. Copyright 2007

Relative Particle Sizes
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Relative Particle Sizes Shown here is the relative difference in particle sizes in this particular soil sample. This would be considered a Coarse Sand because more than 50 percent( by weight) of the soils is retained on the Number 4 sieve. #4 sieve #40 sieve Project Lead The Way, Inc. Copyright 2007

Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading A comparison of Coarse gravel, Fine Gravel aand Coarse Sand next to the number 40 sieve ( ¼” square mesh) Project Lead The Way, Inc. Copyright 2007

Sieve Analysis Results
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Sieve Analysis Results USCS Classification for Coarse Grained Soils Coarse-grained soil, also called granular soil has more than half of the soil grains visible to the naked eye. If the percentage of GRAVEL and SAND is greater than 50%, then the soil is a granular soil. If the soil is predominantly coarse-grained, identify the soil sample as being gravel or sand by estimating whether 50% or more, by weight, of the coarse grains (GRAVEL and SAND) are larger or smaller than the No 4 sieve size. After you have sieved the soil, you need to determine whether the soils is Coarse or Fine Grained Soils. A coarse grained soil, also called a granular soil has more than half of the soil grains visible to the naked eye. If the percentage of GRAVEL and SAND is greater than 50%, then the soil is a granular soil. If the soil is predominantly coarse-grained, identify the soil sample as being gravel or a sand by estimating whether 50% or more, by weight, of the coarse grains (GRAVEL and SAND) are larger or smaller than the No 4 sieve size. Project Lead The Way, Inc. Copyright 2007

USCS Classification for Fine Grained Soils
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading USCS Classification for Fine Grained Soils Fine-grained soils, also called cohesive soils contain greater than 50% SILT and CLAY particles. It is classified further into either SILT or CLAY and them determined if it is high or low plasticity by estimating its dry strength (crushing characteristics), dilatancy (reaction to shaking), and toughness (consistency near the plastic limit) Individual fine- grains are not visible to the naked eye Fine-grained soils, also called cohesive soils contain greater than 50% SILT and CLAY particles. The fine grained soils are classified further into either SILT or CLAY and them determined if it is high or low plasticity by estimating its dry strength (crushing characteristics), dilatancy (reaction to shaking), and toughness (consistency near the plastic limit). The Individual fine- grains are not visible to the naked eye. Project Lead The Way, Inc. Copyright 2007

Determining the Fine Grained Sand Fraction of Soil
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Determining the Fine Grained Sand Fraction of Soil Place the contents of the bottom pan from the sieve test in a Mason jar. Weigh and Record results Fill jar with water so that I it is ¾ full Shake jar with lid on and let the fine sand settle 5 to 10 seconds Drain off Pour the contents of the bottom pan into the Mason jar. Weigh and record this weight. Add water to the jar so that ¾ of the jar is filled. Placed the top on the Mason jar and Shake the jar, allow the fine sand to settle for 5 to 10 seconds. Remove the top, and pour off the dirty water into a 5-gallon pail. Be careful not to spill any of the soil that has settled to the bottom of the jar into the 5 gallon pail. Repeat until water is clear. The material remaining in the Mason jar is the fine grained SAND. SILT, and CLAY that has been removed from the soil sample. Project Lead The Way, Inc. Copyright 2007

Determining the Fine Grained -
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Determining the Fine Grained - Sand, Silt and Clay fraction of the soil sample Pour off the dirty water, be careful not to spill any of the soils at the bottom of jar Repeat the shake, settle and drain off procedure several times Repeat until water is clear Remove the top of the mason jar, and pour off the dirty water into a 5-gallon pail. Be careful not to spill any of the soil that has settled to the bottom of the jar into the 5 gallon pail. Repeat until water is clear. You may have to do this several times. The material remaining in the Mason jar is the fine grained SAND. The SILT, and CLAY that has been removed from the soil sample . Project Lead The Way, Inc. Copyright 2007

Determining the weight of Silt and Clay in Soil Sample
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Determining the weight of Silt and Clay in Soil Sample Place the Mason jar, without top, and the contents into the oven and dry. Weigh the jar and contents. Record the weight and subtract the weight of the empty jar. The difference is the fine grained SAND fraction in the soil sample. Determine the weight of SILT and CLAY in the soil sample Determine the percentage of Silt and Clay in the soil sample To determine the amount of Silt and Clay in the soil sample: Place the Mason jar, without top, and the contents into the oven and let the sample dry. Remove the jar, being careful, as the glass jar will be hot. Weigh the jar and contents. Record the weight and subtract the weight of the empty jar. The difference is the fine grained SAND fraction in the soil sample. Determine the weight of SILT and CLAY in the soil sample. Project Lead The Way, Inc. Copyright 2007

Dilatancy Test Dilatancy is the reaction to wet shaking
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Dilatancy Test Dilatancy is the reaction to wet shaking Prepare a pat of moist soils approximately 3/4 in3 in size Add water, if necessary, to make soil soft but not sticky, like soft putty Place pat in open palm of hand Shake horizontally, striking with other hand several times The Dilatancy Test is the reaction wet shaking. Prepare a pat of moist soil with a volume of about 3 in3. Add enough water, if necessary, to make the soil soft but not sticky, like soft putty. Place the pat in the open palm of one hand and shake horizontally, striking vigorously against the other hand several times. Project Lead The Way, Inc. Copyright 2007

Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Dilatancy Test Observe rapidity of water rising to the surface when sample is shaken and when the sample is squeezed between fingers Speed of appearance during shaking and disappearance when squeezed assists in identifying the fines in the sample If sample become soft and glossy when shaking and then become hard, dull and forms crack when squeezed between the fingers , it has a “reaction to shaking,” or dilatancy” Observe rapidity of water rising to the surface when sample is shaken and when the sample is squeezed between fingers Speed of appearance during shaking and disappearance when squeezed assists in identifying the fines in the sample If sample become soft and glossy when shaking and then become hard, dull and forms crack when squeezed between the fingers , it has a “reaction to shaking,” or dilatancy Project Lead The Way, Inc. Copyright 2007

Dilatancy Test Results
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Dilatancy Test Results Very clean sands give the quickest and most distinct reaction ( S) Rapid reaction, sample is silt ( M) No reaction indicates clay ( C) Based on the reaction when you shake and then squeeze the sample, Very clean sands give the quickest and most distinct reaction ( S) Rapid reaction, sample is silt ( M) No reaction indicates clay ( C) Project Lead The Way, Inc. Copyright 2007

Toughness Test Effect of Water on Fine-Grained Soils
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Toughness Test Effect of Water on Fine-Grained Soils A method of testing the plasticity of the soil is referred to as the Toughness Test. Water is added to the “fines” portion of the soils sample ( those particles that passed the No. 40 sieve) and the sample is then rolled into a 3mm ( 1/8”) diameter thread. A method of testing the plasticity of the soil is referred to as the Toughness Test. Water is added to the “fines” portion of the soils sample ( those particles that passed the No. 40 sieve) and the sample is then rolled into a 3mm ( 1/8”) diameter thread. Project Lead The Way, Inc. Copyright 2007

Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Toughness Test Mixing about a 100 cm ( 1/3 cup of the soil that passed through the No. 40 sieve) with water. Mixture should be the consistency of putty Mix a 100 cm3 ( about 1/3 of a cup) with water and mold to the consistency of putty. If it is too dry, water must be added and if too sticky, the specimen should be spread out in a thin layer and allowed to lose some moisture by evaporation or you can add additional soil . The specimen is then rolled out by hand on a smooth surface or between the palms into a thread about 3 mm ( approximately 1/8” ) in diameter. The thread is then folded and re-rolled repeatedly. As you do this, the moisture content is gradually reduced and the soil specimen stiffens, and finally loses its plasticity, and crumbles when the plastic limit is reached. After the thread crumbles, the pieces should be lumped together and a slight kneading action continued until the lump crumbles. The tougher the thread near the plastic limit and the stiffer the lump when it finally crumbles, the more potent is the colloidal clay fraction in the soil. Weakness of the thread at the plastic limit and quick loss of coherence of the lump below the plastic limit indicate either inorganic clay of low plasticity, or materials such as kaolin-type clays and organic clays. Project Lead The Way, Inc. Copyright 2007

Toughness (Thread Test)
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Toughness (Thread Test) Roll out specimen on a smooth surface until it is approx. 1/8” in diameter. Fold and re-roll thread repeatedly Soil samples moisture content will gradually be reduced Thread breaks and sample becomes lumped Continue until lumps crumble The specimen is then rolled out by hand on a smooth surface or between the palms into a thread about 3 mm ( approximately 1/8” ) in diameter. The thread is then folded and re-rolled repeatedly. As you do this, the moisture content is gradually reduced and the soil specimen stiffens, and finally loses its plasticity, and crumbles when the plastic limit is reached. After the thread crumbles, the pieces should be lumped together and a slight kneading action continued until the lump crumbles. The tougher the thread near the plastic limit and the stiffer the lump when it finally crumbles, the more potent is the colloidal clay fraction in the soil. Weakness of the thread at the plastic limit and quick loss of coherence of the lump below the plastic limit indicate either inorganic clay of low plasticity, or materials such as kaolin-type clays and organic clays. Project Lead The Way, Inc. Copyright 2007

Toughness Test Results
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Toughness Test Results The toughness of the thread that forms when the soil is rolled will identity the fines as either silt or clay. Inability to form thread or very weak thread indicates a plastic silt (ML) Weak spongy thread indicates silt (either organic or inorganic) with a high liquid limit and a low low-plasticity (MH) Firm thread indicates low-plasticity clay (CL) Tough thread indicates highly plastic clay ( CH) The toughness of the thread that forms when the soil is rolled will identity the fines as either silt of clay.. Generally, If the thread is obtain easily the soil is clay. If the thread is difficult to obtain, then the sample is silt. The Inability to form thread or very weak thread indicates a plastic silt ( ML) A Weak spongy thread indicates silt (either organic or inorganic) with a high liquid limit and a low low-plasticity (MH) A Firm thread indicates low-plasticity clay (CL) A Tough thread indicates highly plastic clay ( CH) Project Lead The Way, Inc. Copyright 2007

Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Dry Strength Form a moist pat of approximately 2”-3” in diameter and ½” thick Allow to dry with low heat The crushing characteristic of the soil sample will be evaluated after this sample is completely dry. Dry Strength is a test that evaluates the Crushing characteristics of the soil Mold a pat of soil to the consistency of putty, adding water if necessary. Allow the pat to dry completely by oven, sun, or air drying. Test its strength by breaking and crumbling between the fingers. Project Lead The Way, Inc. Copyright 2007

Dry Strength Test and Results
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Dry Strength Test and Results Dry strength is a measure of the character and quality of colloidal fraction of soil. Break dry pat sample between thumb and index finger This strength is a measure of the character and quantity of the colloidal fraction contained in the soil. The dry strength increases with increasing plasticity. -High dry strength is characteristic for clays of the CH group. -Typical inorganic silt possesses only very slight dry strength. -Salty fine sands and silts have about the same slight dry strength, but can be distinguished by the feel when powdering the dried specimen. Fine sand feels gritty whereas typical silt has the smooth feel of flour. Project Lead The Way, Inc. Copyright 2007

Dry Strength Test Results
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Dry Strength Test Results Breakage Easy – Silt Breakage Difficult - Inorganic Clays of low to medium plasticity Breakage Impossible- Inorganic Clays of high plasticity High dry strength is characteristic for clays of the CH group. Typical inorganic silt possesses only very slight dry strength. Salty fine sands and silts have about the same slight dry strength, but can be distinguished by the feel when powdering the dried specimen. Fine sand feels gritty whereas typical silt has the smooth feel of flour. Silt will break easily Clays with low to medium plasticity will be difficult to break Inorganic clays will be impossible to break Keep in mind that we only used your thumb and index finger to try to break this sample Project Lead The Way, Inc. Copyright 2007

Soils Test Results for Fine Grained Soils
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Soils Test Results for Fine Grained Soils Soils Type This is a summary of the tests performed on the fine grained portion of the soil sample. Project Lead The Way, Inc. Copyright 2007

Soils Types for Foundations
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Soils Types for Foundations Sand and Gravel – Best Medium to hard Clays- Good Soft Clay and Silt- Poor Organic Silts and Clays- Undesirable Peat- No Good - Avoid Identifying the soils type is major factor in determining the type of foundations than can be used. Generally, the better the soils, the higher the bearing capacity and the smaller the footing size. As the soils range from good to poor the cost of the foundatin system will go up. Project Lead The Way, Inc. Copyright 2007

Soil Bearing Capacities
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Soil Bearing Capacities Soil Type Allowable Bearing (lb/ft 2) Drainage BEDROCK 4,000 to 12,000 Poor GRAVELS 3,000 Good GRAVELS w/ FINES SAND 2,000 SAND W/ FINES SILT 1,500 Medium CLAYS ORGANICS 0 to 400 The allowable soils bearing opacities are noted for different types of soils. These are commonly used values and may be referred to as the presumptive soil bearing capacity. Also noted on the chart is the Drainage characteristics of the soil types. Project Lead The Way, Inc. Copyright 2007

What is the site has poor soils, is there anything that can be done?
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Soil Preparation What is the site has poor soils, is there anything that can be done? If the soils at the site are not suitable to carry the foundation loads, the site may have to be prepared using some of the following methods If the soils at the site are not suitable to carry the foundation loads, the site may have to be prepared using some of the following methods Project Lead The Way, Inc. Copyright 2007

Soils Preparations for foundations if soil is undesirable
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Soils Preparations for foundations if soil is undesirable Compaction of the soil- increase the density of the soils and therefore increases the bearing capacity of the soil. Compaction of the soils is down by rolling the soils Bring in “Engineered Fill”, must remove old soils first Blasting to remove rock or soil Some soil preparations that can be done due to poor soils conditions, could be: Compaction of the soil- to increase the density of the soils and therefore increase the bearing capacity of the soil. Compaction of the soils is down by rolling the soil. Bring in “Engineered Fill” , must remove old soils first. This is bring in by truck desirable soils. Blasting to remove rock or soil Project Lead The Way, Inc. Copyright 2007

Soil Types and Properties
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Soil Types and Properties Soils Types and their value as a foundation material is very important. From the chart you can see that Gravel and Gravely Soils are the best for a foundation material, followed by Well Graded Sands or Gravly Sands. Source: U.S. Army Corps of Engineers. (1953). The unified soil classification system. U.S. Army Technical Memorandum, No Project Lead The Way, Inc. Copyright 2007

Soil Description Color: Dark Brown to White
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Soil Description Color: Dark Brown to White Grain size, including estimated maximum grain size is an estimated percent by weight of fines (material passing the No. 200 sieve) : Coarse-grained soils, maximum particle size 2”, estimating 60 percent gravel, 36 percent sand, and 4 percent passing the #200 seive, Gradation: Poorly-graded, insufficient fine gravel Grain shape : Gravel particles well rounded Soil descriptions should describe the significant properties of the soil. As many soils properties that are of interest should be provided. If you are unable to obtain a soil property , you will not have that listed in your description. This is an example of a soil sample . The Soils Description is noted in Red. The soils description can be been written in paragraph form or just listed as shown above. The description should be included noted on the drawings for a given project. Project Lead The Way, Inc. Copyright 2007

Soils Description (continued)
Soil Testing Civil Engineering and ArchitectureTM Unit 4 – Lesson 4.5 – Site Grading Soils Description (continued) Plasticity: Nonplastic Predominant type: Predominantly gravel Secondary components: Considerable sand and trace amounts of nonplastic fines(silt) Classification symbol : GP ( Poorly Graded Gravel and sandy gravel mixture with little or no fines) Other remarks, such as organic, chemical, or metallic content; compactness; consistency; cohesiveness near PL; dry strength and source No dry strength, dense in undisturbed states Project Lead The Way, Inc. Copyright 2007

References: Sowers, G.F. (1979). Introductory Soil Mechanics and Foundations: Geotechnical Engineering,New York, NY: Macmillan Publishing Lindeburg, M. R. (1994). Civil Engineering_Reference Manual (9th ed.). Belmont, CA: Professional Publications, Inc. GGuthrie, P. (2003). Architects portable handbook: First step rules of thumb for building design. NY: McGraw-Hill. Unified Soil Classification August 2004

References (continued):
U.S. Army Corps of Engineers. (1953). The Unified Soil Classification System. U.S. Army Technical Memorandum, No US Army Unified Soil Classification System. [On-line]. Available: (August 5, 2004)

Credits: Writer: Constance Bertucci Content Editor: Narration:
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