LAB 5 - STANDARD PROCTOR COMPACTION TEST CE 383 – Fall 2014 Overview Compaction Densification of soil by application of mechanical energy (removal of air from the voids) Effects of compaction Improves uniformity of soil Improves soil strength and bearing capacity Controls undesirable volume change by frost action, and swelling and shrinkage ASTM Standards ASTM D698 Standard test methods for laboratory compaction characteristics of soils using standard effort ASTM D1557 Standard test methods for laboratory compaction characteristics of soils using modified effort ASTM D2216 Standard test methods for laboratory determination of water content and density of soil and rock by mass Compaction Lab Test Each group will compact soil in a mold following the standard Proctor test method (ASTM D698) Compaction tests will be performed at four/five different water contents to obtain a compaction curve (dry unit weight vs. water content plot) Optimum moisture content corresponds to the maximum dry unit weight Laboratory Equipment Large mixing pan Mold (height=4.6 inch and diameter=4 inch) and a collar Hammer (diameter=2 inch and weight=5.5 lb) Straight edge Knife Balance Drying oven Test Procedure 1. Get a mold (4’’ in diameter) and a hammer (5.5lb for standard Proctor test) from the TA 2. Record the mass and dimensions of the mold 3. Select the water contents at which you will run the Proctor tests (TA will guide you) 4. Mix the desired quantities of soil and water (needed to achieve the Mold and hammer desired wc values) 5. Place the soil in the mold and compact the 1st soil layer with the hammer using 25 blows/layer Test Procedure Hammering pattern (ASTM D698) Test Procedure 6. Scarify the top surface of the 1st layer with a knife to about 3mm in depth prior to placing the 2nd layer 7. Repeat steps 5 and 6 to prepare a compacted sample in three layers 8. Remove the mold collar and screen the top sample surface flat 9. Record the mass of the mold and the compacted soil 10. Extrude the soil sample from the mold and collect soil from the center of the sample to determine its water content 11. Clean the mold 12. Repeat the test for the next water content Standard vs. Modified Proctor Test STANDARD MODIFIED Rammer Weight 5.5 lbs 10 lbs Drop Height 12’’ 18’’ No. of Layers 3 5 Compaction Effort: 4.5 times greater in the modified than in the standard Proctor compaction test Maximum dry unit weight (γd) Optimum Moisture Content (OMC) Water content wc (%) Dry unit weight gd (kN/m3)) Dry unit weight gd (pcf) Compaction Curve Sample Calculations Calculation of the amount of water to be added to soil Trial 1 Total weight of soil = 2.5 kg Initial water content = 8% Target water content = 11% Calculation for existing amount of water: Ww + Ws = 2500 g Ww/Ws = 0.08 Ws = 2500/1.08 = 2315 g Ww = 2315×0.08 = 185 g Calculation of amount of water at wc= 11%: Ww/Ws= 0.11 Ww= 0.11×2315 = 255 g Water to be added to soil: Ww= 255-185 = 70 g No. Height Diameter Mold Dimensions 1 Units 2 3 Volume WATER CONTENT DETERMINATION Description Dish Name Mass of dish Mass of dish + wet soil Mass of dish +dry soil Mass of water Mass of dry soil Water content Symbol No. Md Md,ws Md,ds Mw Ms wc DENSITY DETERMINATION Description Sample No. Assumed water content (Actual) Water content Mass of mold Mass of mold + soil Mass of soil in mold Symbol No. wc,assumed wc,actual Mmold Mmold+soil Msoil 1 8 12.7 4.20 5.65 1.45 2 11 13.6 4.20 6.09 1.89 Moist density gm 1542.60 Dry density gd 1435.29 Optimum water content: Avg. 0.116 0.1016 0.00094 m m m3 Values 1 1.5 24.5 21.9 2.6 20.4 12.7 4 1.35 35.2 30.5 4.7 29.15 16.1 Units g g g g g % 3 14 14.5 4.20 6.38 2.18 4 17 16.1 4.20 6.06 1.86 Units % % kg kg kg 2010.70 2319.22 1978.78 kg/m3 1802.42 2025.34 1680.65 kg/m3 2 1.4 26.5 23.5 3 22.1 13.6 3 1.3 30.5 26.8 3.7 25.5 14.5 Values 14.6 (%) Maximum dry density: 2030 (kg/m3) g d g m 1 w Convert to unit weight c Plotting of Data Compaction Curve 2500.00 Dry Density (kg/m3) 2030 2000.00 1500.00 1000.00 500.00 0.00 10 11 12 13 14 14.6 Moisture Content (%) 15 16 17 Dry Unit Weight Effect of Compaction Effort Zero-air-void Curve E2 (>E1) Line of Optimum E1 Water Content Zero-air-void Curve For a given wc, the theoretical maximum dry unit weight (gd,ZAV) occurs when the degree of saturation S = 1 (i.e., the soil is fully saturated) By substituting S = 1 in the equation below, then gd,ZAV can be obtained for every value of wc gd Ws V G s g wV s Vs Vv G sg w 1 e G sg w 1 G s wc S Lab Activity Complete the data sheet provided in the lab Draw the compaction curve Determine the optimum moisture content and the maximum dry unit weight Draw the zero-air-void curve Safety and Clean up Use lab safety glasses and toe-covering shoes (be careful when using the hammer) Clean up tools and lab space after completion of the tests Questions ?
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