Soils Testing Technician - cttp
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2021 cttp Center for Training Transportation Professionals Soils Testing Technician Course Overview ♦ Terminology ♦ Atterberg Limits ♦ Soil Classification • LL, PL, PI ♦ Sampling ♦ Moisture Density Relationships ♦ Soil Preparation • Standard Proctor ♦ Moisture Content • Modified Proctor • Oven ♦ Compaction • Speedy Moisture Tester • Nuclear Density Gauge ♦ ARDOT Specifications Introduction 4 1
2021 Test Day ♦ Written Exam ♦ Performance Exam • ≈ 60 Questions • 4 Exam Stations • Closed Book Exam ~ Liquid Limit • 2 Hour Time Limit ~ Plastic Limit Proctor • 70 % Overall Required ~ ~ Nuclear Density Gauge to Pass Exam • 2 Attempts Allowed to ♦ Results Pass Each Station • www.cttp.org • Letter & Certificate Introduction 5 Unit Conversions ♦Weight / Mass ♦ Convert 15 lb to grams • 1 ton 2000 lb . • 1 lb 453.6 g = • 1 kg 1000 g ♦ Convert 6804 g to lb = . Introduction 6 2
2021 Terminology ♦ Soil ♦ Testing • Naturally occurring • Grain Size influences unconsolidated rock the stability and maximum load bearing particles, organic capacity of a soil matter, water, and air • Behavior Characteristics predict how a soil will behave to changes in moisture • Density optimizes the engineering properties of the soil for the intended application Introduction 7 Terminology ♦ Air Dried ♦ Oven Dried • Dried at ≤ 140°F • Dried to a constant (60°C) mass at a temperature ~ Chemically bound of 230 ± 9 °F moisture is still present (110 ± 5 °C) in the soil ~ No moisture is present ~ Moisture Content ≠ 0 in the soil sample ~ Moisture Content = 0 Introduction 8 3
2021 Sampling Soils ARDOT 30 Sampling 9 Apparatus ♦Backhoe, auger, post hole digger, shovel ♦Sample Containers • Should prevent the loss of fines and moisture ~ Sealable plastic containers ~ Heavy doubled paper bags are ok if moisture is not to be maintained ~ Unlined cloth or open weave bags should not be used Sampling 10 4
2021 Sampling ♦Sample Numbers • Areas must be enclosed by at least three samples Look for changes in soil ~ Risk factor of failure types, color, or texture ~ Uniformity of soil • Typical Spacing ~ Highway: 200’ – 2000’ ~ Borrow Pits: 100’ – 400’ ~ Earth Dams: 50’ – 150’ Sampling 11 Documentation ♦ Sample Location ♦ Soil Samples • Reference landmarks • Test Pit or Boring # ~ Fence Posts • Material Classification ~ Buildings / Roads ~ Type of material • Sketch ~ Color and classification • Layer Depths ~ Start and end depth of each layer • Comments ~ Water table levels ~ Rock outcrops Sampling 12 5
2021 Test Pit Sampling 13 Boring Sampling 14 6
2021 Dry Preparation of Disturbed Soil… Samples for Test AASHTO R 58 Dry Preparation 15 Apparatus ♦ Drying Apparatus ♦ Pulverizing Apparatus • Fan, heat lamp, oven • Mortar & rubber - covered pestle ♦ Sieves • 2”, ¾”, # 4, # 10, # 40 • Additional sizes as needed by specific test • Power equipment with rubber - covered rollers Individual grain sizes may not be reduced in size ! Dry Preparation 16 7
2021 Procedure ♦ Air dry material ♦ Pulverize material • ≤ 140 °F retained on screen • Rescreen the material ♦ Reduce sample • Split or Quarter • Repeat until all soil particles are separated ♦ Select appropriate sieve according to test ♦ Combine and mix all procedure to be material passing the performed specified screen Use AASHTO R 74 (Wet-Prep) for hard-to- ♦ Process soil over process soils, or soils which need to maintain specified sieve their natural moisture contents Dry Preparation 17 Test Method for Moisture Content of Soils… ARDOT 348 AASHTO T 265 Moisture Content 18 8
2021 ♦ ARDOT Specifications • Oven Drying Field Testing ~ Most Accurate ~ Slow Results • Speedy Moisture ~ Limited to finer grained soils ~ Quick Results ~ No license required • Nuclear Density Gauge ~ Accuracy may fluctuate based on surrounding conditions ~ Quick Results ~ Nuclear license required Moisture Content 19 Apparatus (Oven Drying) ♦ Scales • 0.1 % of sample wt. ~ 10 g → 0.01 g ~ 100 g → 0.1 g ~ 500 g → 0.5 g ♦ Oven • 230 ± 9 °F ♦ Moisture Tins • Corrosion Resistant • Close-fitting Lids Moisture Content 20 9
2021 Procedure ♦ Record number and ♦ Dry sample at 230 °F tare weight of tin to a constant mass • Remove lid ♦ Place “wet soil” into tin • Cover with lid ♦ Remove tin from oven and cool ♦ Record weight of • Cover with lid “Wet Soil + Tare” ♦ Record weight of “Dry Soil + Tare” Moisture Content 21 Calculation ( − ) = % W = wet weight of soil D = dry weight of soil ♦ Report moisture content to the nearest 0.1 % Moisture Content 22 10
2021 Calculation ♦ Determine the moisture content of the soil Wet Wt + Tare 30.62 g ( − ) Dry Wt + Tare 29.55 g = % Tare Weight 18.76 g Wet Soil = 30.62 – 18.76 = 11.86 Dry Soil = 29.55 – 18.76 = 10.79 ( . − . ) . = % = % = . % . . 9.9 % Moisture Content 23 Calculation ♦ Determine the moisture content of the soil Wet Wt + Tare 44.75 g Dry Wt + Tare 40.33 g Tare Weight 13.00 g Moisture Content 24 11
2021 Special Cases ♦ Soil containing ♦ Solutions minerals which have loosely bound water • Oven dry at ≈ 140°F from hydration • Gypsum • Use vacuum desiccation at ≈ 10 mm Hg at a ♦ Soil containing temperature of significant amounts of ≥ 73°F organic materials Moisture Content 26 Sieve Analysis of Soils AASHTO T 11 AASHTO T 27 Sieve Analysis 27 12
2021 Sieve Analysis of Soils ♦ Determines the grain ♦ Differences size distribution of • Soil Sieve Sizes soils ~ 2”, 1½”, 1”, ¾”, 3/8”, #4, #10, #40, #200 ♦ Used for: • Washing • Soil Classification ~ Use wetting agent if necessary • Compliance ~ Allow extra soak time ~ ARDOT Specifications • Embankment • Plating Materials • Select Materials Sieve Analysis 28 ♦ Liquid State • Flows and Introduction changes shape easily ♦ Plastic State -- Liquid Limit -- ♦ Atterberg limits characterize • Moldable Plasticity how a soil will Index and retains behave with shape changes in ♦ Solid State -- Plastic Limit -- moisture contents • Breaks • Liquid Limit rather than • Plastic Limit change • Plasticity Index shape Atterberg Limits 30 13
2021 Plastic Limit of Soils AASHTO T 90 Plastic Limit 31 Introduction ♦Plastic limit is the lowest moisture content at which the soil remains plastic ♦A soil is at its plastic limit when it begins to crumble when rolled to a 3 mm diameter Plastic Limit 32 14
2021 Apparatus ♦ Scale (0.01 g) ♦ Oven 110 ± 5°C • 230°F ♦ Rolling Surface • Ground Glass Plate • Unglazed Paper • Rolling Device ♦ Porcelain Dish ♦ Moisture Tin Referee Test – Hand Roll ♦ Spatula Use distilled, demineralized, or de-ionized water only Plastic Limit 33 Soil Preparation ♦ Air dry the soil • Process soil over # 40 sieve ♦ Add water to soil until moldable • Mix thoroughly • Allow to season ♦ Remove ≈ 10 g • Form soil into a ball Plastic Limit 34 15
2021 Procedure ♦ Record empty tin # ♦ Roll specimen into a and tare weight thread of 3 mm (≈ ⅛”) ♦ Pinch off a small uniform diameter “pea” sized piece of • Roll on ground side of glass plate at 80-90 soil and form an strokes per minute ellipsoidal shape • If thread crumbles ≈ 10 g ≈ 1.5 – 2 g before reaching 3 mm (1st rolling), add water and remix Ball Pea Ellipsoid Plastic Limit 35 Procedure ♦ When thread reaches ♦ Place crumbled soil 3 mm in diameter, portions into tin re-form soil into an • Cover tin with lid ellipsoidal shape • Do not roll past 3 mm ♦ Select another “pea” and repeat process until entire 10 g ♦ Repeat rolling process sample is tested until soil crumbles before reaching or just as it reaches 3 mm Plastic Limit 36 16
2021 Procedure ♦ Immediately weigh tin ♦ Calculate moisture and record the content (MC) “Wet Wt + Tare” ♦ Report Plastic Limit (PL) ♦ Place tin in oven to dry • Round moisture content of sample ♦ Cool sample to room • Report plastic limit to temperature nearest whole number ♦ Weigh and record the “Dry Wt + Tare” Plastic Limit 37 Calculation ♦ Determine the plastic limit of the soil Wet Wt + Tare 26.63 g Dry Wt + Tare 24.14 g 13.43 g 10.94 g Wet Tare Weight 13.20 g Dry ( . − . ) = % = . % = . % . PL = 23 Plastic Limit 38 17
2021 Calculation ♦ Determine the plastic limit of the soil Wet Wt + Tare 31.25 g Dry Wt + Tare 30.10 g Tare Weight 18.70 g Plastic Limit 39 Liquid Limit of Soils AASHTO T 89 Liquid Limit 42 18
2021 Introduction 2 mm The liquid limit of a soil is the moisture content necessary to close a 2 mm wide groove, for a length of 13 mm in 25 blows 13 mm 25 Blows Liquid Limit 43 Apparatus ♦ Scale (0.01 g) ♦ Oven 110°± 5 °C • 230°F ♦ Liquid Limit Machine ♦ Grooving Tool • AASHTO – Curved • ASTM – Flat ♦ Gauge • 10.0 ± 0.2 mm ♦ Mixing Dish / Spatula Liquid Limit 44 19
2021 LL Machine Check ♦ Points of contact ♦ Wear areas ♦ Pin Play / Screws Liquid Limit 45 Calibrate Cup Drop ♦ Dissect the point of ♦ Daily Check contact with smooth side of tape ♦ Lower cup so that it is resting on the base ♦ Insert gauge block until it is in contact with the tape ~ Hold gauge block so that it lies flat against the base Liquid Limit 46 20
2021 Calibrate Cup Drop ♦ Check drop height ♦ Drop Height = 10 mm • Turn crank Adjustment ~ Cup should make a Screw clicking sound without Set Screw lifting from gauge block ♦ To adjust drop height • Loosen set screw • Turn adjustment screw • Tighten set screw ♦ Re-check drop height Remember to remove tape • Reset gauge block when done! • Check drop height Liquid Limit 47 Soil Preparation ♦ Air dry soil ♦ If soil becomes too ♦ Dry or wet prep soil wet, do not add dry using # 40 sieve soil • Use natural ♦ Add water and mix until evaporation soil obtains a stiff consistency • Add water in small increments ~ Adding water too rapidly may produce a “false” liquid limit value Liquid Limit 48 21
2021 Procedure Method B (1 Point) ♦ Record empty tin # ♦ Record empty tare weight • Include lid Liquid Limit 49 Procedure Method B 10 mm (1 Point) ♦ Place soil in cup • Depth of 10 mm • Avoid entrapment of air bubbles within the soil • Cover unused soil to retain moisture Liquid Limit 50 22
2021 Procedure Method B (1 Point) ♦ Divide the soil in the cup with the grooving tool • Cut groove along centerline of cup ~ Up to 6 strokes allowed to reach bottom of cup ~ No more cuts after touching the bottom of the cup • Groove must be 2 ± 0.1 mm wide Liquid Limit 51 Procedure Method B (1 Point) ♦ Turn Crank ♦ # Blows outside 22 - 28 • 2 rev. / second • Adjust moisture & retry • Count # blows • Stop at 13 mm closure ♦ # Blows 22 – 28 • Do not hold device • Immediately verify test ♦ Blow Range 22 - 28 ♦ Verification Test • Redo test ~ Do not adjust moisture • ± 2 blows of previous test • 22 – 28 blows Liquid Limit 52 23
2021 Procedure Method B (1 Point) ♦ Record blow count of verification test ♦ Obtain MC sample • Take sample perpendicular to groove and include the “closed” portion • Sample weight ≥ 10 g ♦ Record “Wet Wt. + Tare” ♦ Dry sample at 230 °F ♦ Cool sample ♦ Record “Dry Wt + Tare” Liquid Limit 53 Procedure Method B (1 Point) ♦ Calculate moisture = content (%) ♦ Correct moisture content to 25 Blows • K-factor ♦ Report • Round corrected moisture content • Report LL to nearest whole number Liquid Limit 54 24
2021 Calculation Method B (1 Point) ♦ Determine the liquid limit of the soil Wet Wt + Tare 31.60 g Dry Wt + Tare 27.14 g 27 blows Tare Weight 14.50 g k27= 1.009 ( . − . ) = % = . % = . % . = = . . = . = LL= 36 Liquid Limit 55 Calculation Method B (1 Point) ♦ Determine the liquid limit of the soil Wet Wt + Tare 30.71 g Dry Wt + Tare 28.32 g 23 blows Tare Weight 13.88 g Liquid Limit 56 25
2021 Procedure Method A (3 Point) ♦ Record three tin #’s ♦ Obtain a MC sample and tare weights and record weights ♦ Obtain proper closure from each closure in each of the ranges ♦ Add additional water to • (1) 25 – 35 Blows adjust MC between • (2) 20 – 30 Blows ≥ 10 closures and mix well • (3) 15 – 25 Blows ♦ Check blow count • No verification difference ♦ Record blow counts • ≥ 10 Liquid Limit 60 Procedure Method A (3 Point) ♦ Calculate all three Flow Curve moisture contents 40 Moisture Content ( % ) ♦ Plot MC vs # Blows 38 • Semi-logarithmic paper 36 • ½ way is ≈ 3/5 34 ♦ Draw “best fit” line 32 LL = 35 ♦ Find MC at 25 blows 30 10 20 30 40 ♦ Report Liquid Limit (LL) Blow Count • Round MC at 25 blows to Blow Range # Blows MC nearest whole number 25 - 35 33 31.5 20 - 30 27 34.2 15 - 25 19 36.7 Liquid Limit 61 26
2021 Calculation ♦ Determine the liquid limit of the soil Flow Curve # Blows MC 40 17 39.1 24 38.5 39 Moisture Content (%) 30 36.2 38 37 36 35 10 20 30 40 Blow Count Liquid Limit 62 Referee Tests ♦ Method A (3 point) ♦ Times ♦ Curved grooving tool • Mixing 5 – 10 min. • Seasoning 30 min. ♦ Use distilled or • Remixing 1 min. demineralized water • Testing 3 min. only • Adjusting 3 min. ♦ No dry soil may be added to the seasoned soil being tested Liquid Limit 64 27
2021 Plasticity ♦Plasticity Index (PI) is the Index of Soils range of moisture contents where the soil AASHTO T 89 exhibits plastic properties • Higher PI Values (> 10) ~ Clayey soils • Lower PI Values (≤ 10) ~ Aggregates ~ Sands ~ Silts Plasticity Index 65 Calculation ♦ Determine the = − plasticity index of the soil PI = Plasticity Index LL = Liquid Limit PL = Plastic Limit LL = 37 PL = 23 = − = ♦ Report PI to the nearest whole number PI = 14 Plasticity Index 66 28
2021 Special Reporting ♦ Report PL ♦ Report PI • “Cannot be • “Non–Plastic (NP)” if Determined” any of the following are ~ If specimen cannot be true rolled to 3 mm ~ LL could not be determined ~ PL could not be ♦ Report LL determined • “Cannot be ~ PL is ≥ LL Determined” ~ If soil “slides” in the cup at blow counts less than 25 Atterberg Limits 67 Classification of Soils… for Highway Construction Purposes AASHTO M 145 Soil Classification 69 29
2021 AASHTO Soil Classification ♦ Granular Materials ♦ Silt / Clay Materials ≤ 35% Passing # 200 > 35% Passing # 200 • Boulder: ≥ 12” • Silt: #200 - .002mm • Cobble: 3”– 12” PI ≤ 10 • Gravel: #10 – 3” • Clay: < .002mm • Sand: #10 - #200 PI ≥ 11 Soil Classification 70 AASHTO Soil Classification Soil Classification 71 30
2021 AASHTO Soil Classification ♦ Classify the following soil as a granular, silt, or clay material and determine the group number of the soil > 35% Passing # 200 = Silt or Clay = A4, A5, A6, or A7 PI ≤ 10 = Silt = A4 or A5 LL ≥ 41 = A5 Silt - Group A5 Soil Classification 72 Water Water 73 31
2021 Water ( − ) WA Air = % WW Water ♦ W – wet weight of soil W ♦ D – dry weight of soil D Solids (dry soil) = + Water 74 Water ♦ Δ MC - % Desired change in moisture content ∆ = − ♦ Water needed for a desired Δ MC when: Dry weight of soil is known = % Water 75 32
2021 Water ♦ The dry weight of a soil sample is 2000.0 g. How much water will need to be added for the soil to contain 3 % moisture ? = % % = = . = % 60 g or 60 mL Water 76 Water Calculation ♦ The dry weight of a soil sample is 2500.0 g. How many mL of water will need to be added for the soil to contain 10.2 % moisture ? Water 77 33
2021 Water ♦ Water needed for a desired Δ MC when: Wet Weight of soil known . = This equation is the + % moisture content equation rearranged . Δ = − Δ . = % Water 79 Water ♦ A 2630 g soil sample has a moisture content of 3.4 %. How many mL of water do you need to add to bring the soil sample to 12.0 % moisture? . = = = = . . % . + + % . = − = . % − . % = . % ∆ . % . = = . = % % 219 mL Water 80 34
2021 Water Calculation ♦ A 5500 g soil sample has a moisture content of 1.3 %. How many mL of water do you need to add to bring the soil sample to 6.2 % moisture? Water 81 Determining Moisture Content by Speedy Moisture Tester ARDOT 347 Speedy MC 85 35
2021 Introduction ♦ Alternative method to ♦ Calcium carbide reacts oven drying for fine with the water in the grained soils soil • Not quite as accurate ♦ Reaction produces • Quicker test acetylene gas • No license to operate ♦ Gas pressure inside the meter is measured and converted to a moisture content • Based on wet mass Speedy MC 86 Introduction ♦ Testers come in many ♦ Caution – Calcium sizes and require carbide reacts violently different standard with water sample sizes • 20 g Tester • 26 g Tester • 200 g Tester ♦ Standard sample size for this class is 20 g Speedy MC 87 36
2021 Procedure ♦ Clean tester Note : Procedures are written for chamber and cap a Standard Sample Size of 20 g prior to use ♦ Tilt chamber on side and roll (2) steel balls into chamber • Avoid dropping balls directly onto pressure port Speedy MC 88 Procedure ♦ Place 3 scoops (≈ 24 g) of calcium carbide into chamber ♦ Prepare soil sample • Pulverize or break into small pieces Speedy MC 89 37
2021 Procedure ♦ Weigh out 20 g of soil ♦ Keep chamber on it’s • Check your individual side and secure the tester specifications cap • Prevents soil mixing with reagent ♦ Place soil into cap Speedy MC 90 Procedure ♦ Raise tester to a vertical position • Soil must mix with reagent to produce gas ♦ Shake horizontally with a circular rotating motion for approximately 1 to 2 minutes Speedy MC 91 38
2021 Procedure ♦ Read dial What does this dial • Dial Decreasing – Leak read? ~ Invalid Test – Redo 11.7 % • Dial Increasing – Reaction not complete ~ Repeat shaking until gauge dial stabilizes ~ Obtain 3 consecutive identical readings What does this dial read? ♦ Record final dial reading (0.1 %) 11.7 % Speedy MC 92 Procedure ♦Remove cap • Point cap in a safe direction and slowly release gas pressure ♦Examine contents and repeat test if sample is not completely pulverized • Properly dispose of contents ♦Avoid: • Breathing Fumes • Sources of ignition Speedy MC 93 39
2021 Calculation ♦ Record moisture content • Use ARDOT correction chart to convert from % of wet mass to % of dry mass ♦ Report • Report moisture content to the nearest 0.1% Speedy MC 94 Calculation ♦ Determine the moisture content of the soil Sample Weight 20 g Dial Reading 9.3 • If the standard sample weight was used, read the moisture content directly from the ARDOT correction chart MC = 10.1 % Speedy MC 95 40
2021 Special Cases ♦ Very low moistures ♦ Very high moistures • Double the sample size • Cut the sample size in ~ Use 40 g of soil instead half of 20 g ~ Use 10 g of soil instead of 20 g • Divide dial reading by 2 before going to the • Multiply dial reading by conversion chart 2 before going to the conversion chart Speedy MC 96 Special Cases ♦ Determine the moisture • Read moisture content content of the soil from conversion chart based on calculated value Sample Weight 10 g Dial Reading 11.5 % • Sample weight cut in half • Multiply dial reading by 2 before going to the chart 11.5 x 2 = 23.0 MC = 29.8% Speedy MC 97 41
2021 Special Cases ♦ Determine the • Read moisture content moisture content of from conversion chart the soil based on calculated value Sample Weight 40 g Dial Reading 7.6 % • Sample weight doubled • Divide dial reading by 2 before going to the chart 7.6 / 2 = 3.8 MC = 4.1% Speedy MC 98 Calculation ♦ Determine the moisture content of the soil Sample Moisture Dial Reading Chart Weight Content 20 g 15.3 % 10 g 13.6 % 40 g 4.6 % Speedy MC 99 42
2021 Moisture Density Relations of Soils AASHTO T 99 AASHTO T 180 Proctor 103 Compaction ♦Compaction • Densification of a soil by applying a load to the soil ~ Reduces settlement ~ Increases shear resistance ~ Reduces permeability ♦Moisture affects compaction • Compaction at the optimum water content results in the greatest density for a specified compactive effort Proctor 104 43
2021 Compaction Below Opt. MC Optimum MC Above Opt. MC • Soil particles • Soil particles • Soil particles pack loosely pack closely pack in layers • Weak, permeable • Interlocking soil (shear planes) soil structure structure • Non-interlocking • Compaction is • Compacts soil structure more difficult moderately easy • Compacts easily • Stable soil • Stable soil • Non-stable soil structure is structure structure typical questionable Proctor 105 Proctor Curves ♦ The relationship ♦ Proctor curves serve between moisture and as the basis for field density establishes the compaction proctor curve of a soil • Maximum Dry Density ~ Used in the field to determine the % compaction of the soil • Optimum Moisture ~ Used in the field as a target to help achieve the desired degree of compaction and prevent instability of the soil structure Proctor 106 44
2021 Apparatus ♦ Sieves ♦ Straight Edge • 3/4in. or # 4 ♦ Moisture Tins ♦ Scales ♦ Rammer • Readable to 1 g • 5.5 lb – 12” drop • Readable to 0.1 g (MC) • 10.0 lb – 18” drop ♦ Oven (230 ± 9 °F) ♦ Mold Assembly • 4” or 6” I.D. • Solid or split side Proctor 107 AASHTO Proctor Specifications ♦ T 99 (Standard) ♦ T 180 (Modified) • 5.5 lb Rammer • 10 lb Rammer • 12” Drop • 18” Drop Proctor 108 45
2021 AASHTO Proctor γ = ∙ γ Specifications 1 + ∙ 100 Zero Air Voids Modified Proctor : 56,000 ft-lb/ft³ Standard Proctor : Modified 12,400 ft-lb/ft³ Proctor Compactive Effort • Hammer Weight • Drop Height Standard • Number of Lifts Proctor ARDOT Limit : ≈ 105 % Compaction Proctor 109 ARDOT Specifications ♦ Proctor method is based on the gradation of the field soil • Section 210.10 – Compacted Embankment Proctor 110 46
2021 Procedure ♦ Soil Preparation • Determine the gradation of the field soil ~ 2”, 3/4”, # 4 sieves • Select the appropriate procedure and method based on the gradation of the soil or other specifications • Air dry field sample and process sample over the appropriate sieve (# 4 or 3/4”) • Continue air drying processed sample until the desired starting moisture content is obtained Proctor 111 Procedure ♦ Reduce processed ♦ Select increment sample and obtain a • Increment - consistent representative change in moisture portion(s) content between points ~ Usually 1 – 2 % • Rocky soils or heavy ~ Maximum of 2½ % clays require individual portions 2% 2% 2% ~ 4” Mold ≈ 2500 g ~ 6” Mold ≈ 6000 g 10% 12% 14% 16% • Other soil types allow reuse of soil Proctor 112 47
2021 Procedure ♦ Determine the amount ♦ Mix water into soil to of water to be added achieve a uniform moisture content Proctor 113 Procedure ♦ Allow soil to “season” if necessary • Heavy clays must “season” for a minimum of 12 hours prior to compaction • Place in sealable container(s) Proctor 114 48
2021 Procedure ♦ Tighten joint on split ♦ Attach mold firmly to molds to maintain base constant volume Proctor 117 Procedure ♦ Record weight of ♦ Attach collar to mold empty mold assembly (mold + base) Proctor 118 49
2021 Procedure ♦ Add soil for 1 lift into mold • Evenly distribute soil in mold ♦ Gently tamp soil surface • Eliminates loose state ♦ Solid Compaction Surface • 200 lb concrete block • Sound concrete floor Proctor 119 Procedure ♦ Compact lift evenly ♦ Trim soil around mold using the appropriate edges and distributed number of blows evenly across the surface “Pumping” ♦ Repeat process for remaining lifts Proctor 120 50
2021 Procedure ♦ Remove collar ♦ Trim excess soil with a Height of soil straightedge so that the above mold ≈ ¼ - ½ inch soil surface is even with the top of the mold • Check for hammer marks ~ Re-compact point if hammer marks are seen • Patch holes caused by trimming Proctor 121 Procedure ♦ Clean outside of mold ♦ Record weight of filled • Check under base mold assembly Proctor 122 51
2021 Procedure ♦ Extrude specimen ♦ Obtain a moisture content specimen • Use full slice ♦ Record weights ARDOT 348 Passing # 4 100 g min. Passing ¾” 500 g min. Proctor 123 Procedure ♦ Repeat compaction After which point could process for all points you stop compacting points? ♦ Compact points until: • There is no increase in Target Wet Mass the wet mass of soil, 10 % 4300 g and then perform one more determination 12 % 4380 g • There are at least 2 14 % 4400 g points over optimum 16 % 4360 g • Points increase in mass and then 18 % 4310 g decrease in mass Stop ! Proctor 124 52
2021 Proctor Curve ♦ Plot Proctor Points ♦ Draw Proctor Curve • X - axis : % Moisture • Decide ≈ peak location • Y - axis : Dry Density • Draw smooth parabola ♦ Record Peak Values 120 • Maximum Dry Density Dry Density (lbs/ft³) • Optimum Moisture Content 110 100 ♦ Report Density & MC • Max DD: nearest 0.1 lb/ft³ 10 12 14 16 • Opt. MC: nearest 0.1% % Moisture Proctor 125 Proctor Curve 115 114 113 Max. Dry Density (pcf) 112 111 110 109 108 107 106 105 0 2 4 6 8 10 12 14 16 18 20 Moisture Content (%) Proctor 126 53
2021 Peak Location by Graphing 127 126 1 125 2 Dry Density (pcf) 124 123 122 3 121 120 119 8 9 10 11 12 13 14 15 16 17 18 Moisture Content (%) Proctor 127 Peak Location by Graphing DD Max = 126.2 @ 13.5% 127 126 125 Dry Density (pcf) 124 123 122 121 120 119 8 9 10 11 12 13 14 15 16 17 18 Moisture Content (%) Proctor 128 54
2021 Practice Proctor Graphs 130.0 130.0 129.0 129.0 128.0 128.0 127.0 127.0 126.0 126.0 125.0 125.0 124.0 124.0 123.0 123.0 122.0 122.0 121.0 121.0 120.0 120.0 8 9 10 11 12 13 14 15 16 8 9 10 11 12 13 14 15 16 Proctor 129 Practice Proctor Graphs 130.0 130.0 129.0 129.0 128.0 128.0 127.0 127.0 126.0 126.0 125.0 125.0 124.0 124.0 123.0 123.0 122.0 122.0 121.0 121.0 120.0 120.0 8 9 10 11 12 13 14 15 16 8 9 10 11 12 13 14 15 16 Proctor 130 55
2021 Practice Proctor Graphs 130.0 130.0 Add point close to Add points to finish 129.0 129.0 optimum moisture proctor ! 128.0 content ! 128.0 127.0 127.0 126.0 126.0 125.0 125.0 124.0 124.0 123.0 122.0 121.0 ? 123.0 122.0 121.0 120.0 120.0 8 9 10 11 12 13 14 15 16 8 9 10 11 12 13 14 15 16 Proctor 131 Practice Proctor Graphs 130.0 130.0 Use rules only with 129.0 129.0 evenly spaced 128.0 Fire the 128.0 moisture contents ! 127.0 technician ! 127.0 126.0 126.0 125.0 125.0 124.0 124.0 123.0 123.0 122.0 122.0 121.0 121.0 120.0 120.0 8 9 10 11 12 13 14 15 16 8 9 10 11 12 13 14 15 16 Proctor 132 56
2021 Peak Location by Graphing 140 Remember, you must have evenly DD Max = 126.5 @ 10.8% spaced moisture 135 contents for this Dry Density (pcf) method ! 130 1 Never use straight 125 2 lines through data 3 points to establish peak! 120 Peak values obtained by using straight 115 lines are too high for 8 9 10 11 12 13 maximum density. Moisture Content (%) Proctor 133 Graphical Parabola Method 140 DD Max = 126.0 @ 10.8% 135 Optimum MC is halfway between Dry Density (pcf) 130 F E point A & H K J . + . 125 B = = . % C G 120 A D H 115 8 9 10 11 12 13 Moisture Content (%) Proctor 134 57
2021 Graphical Parabola Method 140 135 DD Max = 126.0 @ 10.8% Dry Density (pcf) 130 B 125 C 120 A 115 8 9 10 11 12 13 Moisture Content (%) Proctor 135 Calibration of Measure AASHTO T 19 Section 8 Mold Volume 136 58
2021 Procedure ♦ Clean and dry mold and base plate ♦ Place a thin layer of grease on upper and lower mold rims ♦ Assemble mold and base plate ♦ Weigh glass plate and mold assembly Mold Volume 137 Procedure ♦ Fill mold with water and cover with glass plate • Eliminate bubbles and excess water • Dry mold assembly and glass plate ♦ Weigh mold, water and glass plate Mold Volume 138 59
2021 Procedure ♦ Measure temperature of water to nearest 1° F ♦ Determine the density of the water at the measured temperature • AASHTO Table 3 ~ Interpolate ♦ Calculate the volume of the mold Mold Volume 139 Procedure ♦ Calculate volume of mold = ♦ Report volume of mold to the nearest 0.0001 ft³ Mold Volume 140 60
2021 Calculation ♦ Determine the volume of the mold Mold + Plate 2.426 lb Density of Mold + Water + Plate 4.500 lb Water @ 76° Temperature 76 °F 62.252 lb/ft³ = ( . − . ) . = = = . = . . . V = 0.0333 ft³ Mold Volume 141 Calculation ♦ Determine the volume of the mold Mold + Plate 15.248 lb Mold + Water + Plate 19.928 lb Temperature 68 °F Mold Volume 142 61
2021 Mold Volumes ♦ 4” Mold • 0.0333 (Tolerance of ± 0.0005 ft³) ♦ 6” Mold • 0.0750 (Tolerance of ± 0.0009 ft³) ♦ Use mold volume determined by AASHTO T 19 for density calculations Mold Volume 144 Density Calculations = = = = = + % + % = = = (%) Proctor 148 62
2021 Density Calculations ♦ Wet Density (WD) − = = = • Convert units as needed ~ lb/ft³ ~ kg/m³ Proctor 149 Density Calculations ♦ Compute the wet density (lb/ft³) of a soil compacted in a 4” diameter mold with a volume of 0.0336 ft³ 6398.6 g Mold Weight 4454.0 g - 4454.0 g Mold + Soil 6398.6 g 1944.6 g 1) Find the wet weight of soil . = . 2) Convert to pounds . / 3) Divide by volume . = . / ³ . ³ Proctor 150 63
2021 Density Calculations ♦ Once WD is known, the dry density (DD) is calculated based on the MC of the soil cut from the compacted specimen = + % ♦ Determine the dry density of a soil having a WD of 127.589 lb/ft³ and MC of 12.2 % . . = = = . = . ൗ . % . ³ + % Proctor 151 Sample Proctor ♦ Sample Proctor Data Mold Volume 0.0334 ft³ Empty Mold + Soil Soil Wet Moisture Dry Mold Wt Soil Wt Weight Weight Density Content Density (g) (g) (g) (lb) (lb/ft³) (%) (lb/ft³) 4475.0 6433.3 10.5 4475.0 6512.4 11.5 4475.0 6520.9 12.5 4475.0 6460.3 13.5 = = + % Proctor 152 64
2021 Sample Proctor ♦ Sample Proctor Data 122 121 120 Dry Density (pcf) 119 118 117 116 115 10 11 12 13 14 Moisture Content (%) Proctor 154 Proctor Adjustments ♦ An increase or decrease in the amount of rock in the field will change the maximum dry density and optimum moisture content of the soil ♦ Adjustments are only made when the change would not require a different proctor method to be run ♦ Field Indicators for Adjustments : • High density tests (continuously without reason) • Low density tests (continuously without reason) • Visual noticeable change in soil gradation Proctor 156 65
2021 Proctor Adjustments ♦ Adjusts the maximum dry density and optimum moisture content of a soil to account for the coarse particles (rock) found in field conditions • ARDOT Material Replacement Method (ARDOT) ~ Alters the way the proctor is run by substituting smaller rock which is allowed in the mold, for larger rock not allowed in the mold by the AASHTO method • AASHTO Correction of Maximum Dry Density and Optimum Moisture for Oversized Particles (AASHTO COP) ~ Mathematically corrects the established AASHTO proctor by using actual material properties and the percentages of soil and rock found in the field Proctor 157 ARDOT Proctor Adjustments ♦ AASHTO T 99 A Proctors • If more than 5 % is retained on the # 4 sieve, run the AASHTO proctor and apply the AASHTO correction for oversized particles on # 4 sieve ♦ AASHTO T 99 C or T 180 D Proctors • If material is retained on the ¾” sieve, use the A RDOT material replacement method when running the AASHTO proctor Proctor 158 66
2021 Proctor Adjustments ♦ What proctor should ♦ What proctor should be performed for the be performed for the soil with the following soil with the following gradation? gradation? Sieve % Passing Sieve % Passing 2” 100 2” 100 3/4” 100 3/4” 100 #4 96 #4 64 # 200 15 # 200 8.7 AASHTO T 99 A AASHTO T 180 D Proctor 159 Proctor Adjustments ♦ What proctor should ♦ What proctor should be performed for the be performed for the soil with the following soil with the following gradation? gradation? Sieve % Passing Sieve % Passing 2” 100 2” 100 3/4” 100 3/4” 92 #4 93 #4 77 # 200 13 # 200 10 AASHTO T 99 A AASHTO T 99 C with AASHTO COP with ARDOT Proctor 160 67
2021 ARDOT Material Replacement % Ignore % Ret. Material 2% on 2” Sieve Replacement Sieve Passing 2” 2” 14 % 3/4” 3/4” 24 % 38 % #4 #4 60 % 60 % Proctor 161 ARDOT Material Replacement ♦ Batching 5500 g / Point • 98 % of material passes 2” sieve = . • 38 % of (3/4” - # 4) Rock is ( )( . ) = needed for each point • 60 % of (minus # 4) Soil is needed for each point ( )( . ) = 2133 Rock + 3367 Soil 5500 Point Proctor 162 68
2021 AASHTO Correction for Oversized Particles ♦ Run Bulk Specific Gravity (Gsb) of Rock • Gsb= 2.588 ♦ Calculate corrected proctor value and ♦ Run Proctor optimum moisture • AASHTO T 99 A content ~ AASHTO COP • Worksheet • Max. DD = 116.6 pcf • Opt. MC = 14.2 % Proctor 163 AASHTO Correction for Oversized Particles Compacted Laboratory Dry Density Corrected to Field Dry Density (PC) % Coarse Material (0.1) (field) 7.4 (PF) % Fine Material (0.1) 100 - (PC) 92.6 (MCC) Moisture Content of Coarse Material (assume 2%) 2.0 (MCF) Moisture Content of Fine Material (proctor) 14.2 + (MCT) Corrected Total Moisture Content 13.3% (DF) Dry Density of Fine Material (proctor) 116.6 Gsb Bulk Specific Gravity of Coarse Mat. (lab test) 2.588 (k) Unit Weight of Coarse Material Gsb x 62.4 = 2.588 x 62.4 161.491 (Dd) Corrected Total Dry Density + 119.0 pcf Proctor 164 69
2021 In-Place Density and Moisture Content of Soil by Nuclear Methods AASHTO T 310 Density Gauge 167 Apparatus ♦ Nuclear Densometer Extraction Tool Drill Rod Scraper Plate Reference Standard Density Gauge 168 70
2021 Density Gauge ♦ Direct Measurements ♦ Calculated Values • Wet Density • Dry Density • Moisture Content = 1 + 100 % • % Compaction % = 100 % Density Gauge 169 Density Gauge ♦ Modes of Operation • Direct Transmission ~ Measures the density of the material between the source and the surface • Backscatter ~ Measures the density of the material close to the surface (80% in top 2”) Density Gauge 170 71
2021 Density Gauge ♦ Wet Density Measurement • Source - Cesium 137 Direct Transmission ~ Gamma Photons • Detectors ~ Geiger – Mueller • Measurement SOURCE Cs 137 ~ The higher the density of a material, the lower the count values Density Gauge 171 Density Gauge ♦ Moisture Measurement • Source – Am 241: BE 9 ~ Neutrons • Detectors ~ Helium – 3 • Measurement ~ Neutrons are slowed by collisions with hydrogen ~ Measurement depth is a function of the moisture content (unknown) Density Gauge 172 72
2021 Calibration ♦ Radioactive Sources ♦ Source Rod Positions • Aging changes the relationship between SAFE POSITION INDEX TRIGGER count rates and gauge BACKSCATTER POSITION outputs 2 in. SOURCE ROD INDEX ROD DIRECT TRANSMISSION POSITIONS ♦ Calibration • Initially 12 in. • 24 months ~ Or yearly verification Density Gauge 173 Troxler 3430 ♦ Keypad (READY) 1 min Depth : 4 inches ON MA YES STD SPECIAL PR OFF START TIME DEPTH NO ENTER Density Gauge 174 73
2021 Standard Count ♦ Adjusts for source decay and background radiation • Used daily to determine the proper functioning of gauge ♦ Site Selection • Concrete or Asphalt Safe Position • ≥ 10’ from large objects • ≥ 30’ from any other radioactive sources ♦ Run Standard Count • Place gauge on Standard Block • Rod in “Safe” position • Press Standard Block Metal Butt Plate Density Gauge 175 Standard Count ♦ Determine Compliance ♦ Troxler, Humbolt, • Use procedure InstroTek, & CPN recommended by the Gauges require : gauge manufacturer • If none given by manufacturer, use • ± 1 % Density = ± 1.96 / • ± 2 % Moisture ~ Ns = new standard count • From the average of ~ No = average of last 4 the last 4 standard standard counts counts taken ~ F = pre-scale factor Density Gauge 176 74
2021 Standard Count Compliance Ratio Method ♦ Average last 4 counts ♦ Determine Ratios • Density (± 1 %) Date DS MS Ratio Range = 0.99 – 1.01 May 5th 2251 650 ~ 2234 / 2258 = 0.9893 F ~ 2258 / 2234 = 1.0107 May 6th 2260 642 May 7th 2258 645 • Moisture (± 2 %) May 8th 2262 648 Ratio Range = 0.98 – 1.02 ~ 638 / 646 = 0.9876 Average 2258 646 P ~ 646 / 638 = 1.0125 ♦ Take new standard ♦ Determine Pass/Fail New Counts 2234 638 • Fails – Both must pass Density Gauge 177 Standard Count Compliance Range Method ♦ Average last 4 counts ♦ Determine Ranges Date DS MS • Density (± 1 %) 2258 x 0.01 = ± 22 May 5th 2251 650 F ~ 2258 - 2234 = 24 May 6th 2260 642 May 7th 2258 645 • Moisture (± 2 %) May 8th 2262 648 646 x 0.02 = ± 12 Average 2258 646 P ~ 646 - 638 = 8 ♦ Take new standard ♦ Determine Pass/Fail New Counts 2234 638 • Fails – Both must pass Density Gauge 178 75
2021 Standard Count Compliance ♦ Average last 4 counts ♦ Determine if the new density and moisture Date DS MS standard counts pass May 10th 2275 588 or fail May 12th 2260 551 May 13th 2265 565 May 15th 2262 556 ♦ New Standard 2246 575 Density Gauge 179 Standard Count Compliance ♦ Failing Standard Counts 1. Re-run standard count ~ Check set-up 2. Establish a new average ~ Run 4 new standard counts • Gauge Drift Best Practice • Max. Deviation DS = 25 • Max Deviation MS = 12 ~ Run new standard count and compare to new average • Pass – Proceed to testing Fail – Repair gauge Density Gauge 181 76
2021 Standard Count Compliance ♦ Passing Standard Counts • Proceed to testing Density Gauge 182 Procedure ♦ Prepare Surface • Remove any dry or loose materials • Smooth and level soil surface • Fill any voids with native fines or sand ~ No more than 10% of footprint should be filled ~ Filler pad thickness should not exceed 1/8” in depth Density Gauge 183 77
2021 Procedure ♦ Determine Test Depth • Equal to lift thickness ~ Test Depth is to be entered into gauge ~ Test Depth is the depth the rod should be 8 in. extended to 10 in. • Test depth should never exceed lift thickness Test Depth = 8 inches Density Gauge 184 Procedure ♦ Drill Hole • Hole should be at least 12” 2 inches deeper than 10” test depth 8” 6” • Pin markings include 1st 4” the extra 2” required 2” – Ring 2” 2” + Extra 2” Density Gauge 185 78
2021 Procedure ♦ Drill Hole • Place scraper plate on prepared test site • Attach extraction tool and insert drill rod • Step firmly on center of plate and hammer drill rod at least 2” deeper than test depth ~ Perpendicular to surface Density Gauge 186 Procedure ♦ Remove drill rod with ♦ Mark plate footprint an upward, twisting and hole location motion ♦ Remove tools from area • ≈ 3 ft away Density Gauge 187 79
2021 Procedure ♦ Check gauge parameters • Time (1 minute) • Depth (lift thickness) • Max. Density (proctor) ♦ Place gauge in footprint • Align rod with hole marks ♦ Lower rod to test depth ♦ Snug gauge back against hole • Check contact with soil Density Gauge 188 Procedure ♦ Snug gauge back ♦ Start Test against hole • Check contact with soil Push → ♦ Move away from gauge • ≈ 3 feet Density Gauge 189 80
2021 Procedure ♦ Safe Rod ♦ Error Sources! • Source rod not “clicked ♦ Record Data into position” • Wet Density • Depth set incorrectly • Dry Density • Gaps under gauge • % Compaction after rod insertion • % Moisture • External causes ~ Ground Vibration • Location ~ Drainage structures ~ Power lines Density Gauge 190 What’s wrong ? Density Gauge 191 81
2021 What’s wrong ? Density Gauge 192 % Compaction ♦ Correct proctor value was active in the gauge at the time of testing and true moisture content returned by the gauge % = % ♦ Proctor value was not available at the time of testing % = % = % % Compaction 193 82
2021 Calculation ♦ Determine the % compaction Gauge DD 113.0 lb/ft³ @ 12.4 % Proctor 115.9 lb/ft³ @ 14.0 % % = % . % = % = . % = . % . % PR = 97.5 % % Compaction 194 Calculation ♦ Determine the % compaction Gauge DD 135.6 lb/ft³ @ 6.3 % Proctor 138.0 lb/ft³ @ 6.5 % % Compaction 195 83
2021 Calculation ♦ Determine the % compaction and if the site meets the required specifications Test DD MC Gauge (8 % Coarse) 114.0 pcf 12.5 % Proctor (0% Coarse) 116.0 pcf 14.0 % Proctor (8% Coarse) 119.3 pcf 13.0 % Specifications ≥ 98 % ±1% . % = % = . % = . % . Fails Density – Passes Moisture % Compaction 197 Moisture Offset ♦ Corrects the gauge’s ♦ Take gauge MC readings inaccurate moisture at 5 different locations content readings due ♦ Collect moisture to substances found in samples from center of the soil footprint at each location • Cement, Gypsum, Coal, • Run oven dry moisture Lime (- correction) contents ~ High Hydrogen Forms ♦ Compute moisture offset • Boron, Cadmium, according to the gauge Chlorine (+ correction) manufacturer’s ~ Neutron Absorbing recommendations Offsets 198 84
2021 Trench Offset ♦ Corrects moisture and ♦ Take a normal standard shallow density count outside trench readings ♦ Put gauge on standard ♦ Use anytime gauge is block inside trench within 2 feet of a • Take a four minute vertical soil structure reading with the rod in the “safe” position 2 ft ♦ Record trench counts Offset = Trench - Standard Offsets 199 ARDOT Specifications ARDOT specification limits are considered absolute limits ! • Observed or calculated values are not rounded for determination of compliance ~ Compared directly with the limit ~ Average values are rounded to the same # of significant digits • Any deviation outside limits is non-compliance ~ Failing test ARDOT Specifications 200 85
2021 ARDOT Specifications ♦ Density Specifications • Embankment ≥ 95 % Compaction • Subgrade ≥ 95 % Compaction • Base Aggregate ≥ 98 % Compaction ♦ Moisture Specification • ARDOT Moisture “At or near opt. moisture” ARDOT Specifications 201 ARDOT Specifications ♦ Base Aggregate ♦ Compacted Embankment • Test Quantities • Test Quantity ~ Contractor - 1000 tons ~ 3000 yd³ / 1 per lift ~ ARDOT - 4000 tons min. • Tests for QC • Tests for QC ~ Density & Moisture ~ Gradation ~ Density & Moisture ♦ Granular Borrow Plasticity Index ~ • Additional Tests for QC ~ Thickness if Specified ~ Gradation • Sounding ~ Plasticity Index ARDOT Specifications 202 86
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