350 likes | 952 Views
Proctor Test (AASHTO T 99*, T 224 & T 272. Topic J. * Replacement Procedure is no longer applicable. Figure 4: M-D Graph. AASHTO T-99 – Methods A and C. Compact soil in mold in three equal lifts. Each layer is compacted with a hammer that weighs 5.5 lbs with a free fall of 12 inches.
E N D
Proctor Test (AASHTO T 99*, T 224 & T 272 Topic J * Replacement Procedure is no longer applicable Topic J
Figure 4: M-D Graph Topic J
AASHTO T-99 – Methods A and C • Compact soil in mold in three equal lifts. • Each layer is compacted with a hammer that weighs 5.5 lbs with a free fall of 12 inches. • Each layer is compacted 25 times with the hammer. • When method B or D are required each layer is compacted 56 times with the hammer. Topic J
Sample Preparation (AASHTO T 99) • Dry Sample below optimum moisture content. • % retained on No. 4 sieve (Method A or B) • % retained on ¾ inch sieve (Method C or D) • Used for determining rock correction factor. Topic J
Proctor - Procedures • Mix sample with water • Compact specimen in mold • Remove extension collar and trim soil • Weigh mold and wet soil • Subtract mold weight and multiply by 30 cf • Remove soil and test for moisture content • Repeat four more times at greater moisture content Topic J
Figure 4: M-D Graph Topic J
Student Problem (J-3) • The Moisture/Density relationship of clay is 105.9 pcf at 22.9% moisture. Calculate. Topic J
Determining Percent Compaction/Moisture • Percent Compaction = (Measured Dry Density/Maximum Dry Density) * 100% • Percent Optimum Moisture Content = (Measured Moisture Content/Optimum Moisture Content)*100% Topic J
Student Problem (J-3) • The Moisture/Density relationship of clay is 105.9 pcf at 22.9% moisture. Calculate. 82.5% 92.7% 100.0% 100.3% 131.1% 84.2% Topic J
Student Problem (J-5)Sample Preparation • The weight of the total sample in grams is 6356. The actual moisture of the soil is 2.0%. The desired moisture content to be achieved is 7.0%. Calculate the milliliters of water needed to obtain the desired moisture content? • One milliliter of water equals 1 gram Topic J
Student Problem (J-5)Sample Preparation • Weight of sample (W) = 6356 grams • Actual moisture of soil (A) = 2.0% • Desired moisture content (OM) =7.0% • Calculate ml of water needed? Topic J
Student Problem (J-5) • D= Difference in moisture content D = OM - A D = 7.0 – 2.0 = 5.0 Topic J
Student Problem (J-5) • F= Percent moisture factor F = D/100 F = 5.0/100 = 0.05 Topic J
Student Problem (J-5) Water needed = W x F Water needed = 6356 g x 0.05 = 317.8g 1 gram = 1 milliliter 317.8 g = 317.8 ml Topic J
Determining Moisture Content (w)From Lab Test • Moisture content is the ratio of weight of water in soil sample to weight of solid particles in a given soil sample. • w = (Ww /Ws) * 100% • Ww = Weight of Water • Ws = Weight of Solids Topic J
Determining Moisture Content (w)From Lab Test A = Weight of container and wet soil = 100 grams B = Weight of container and dry soil = 75 grams C = Weight of container = 20 grams w = Moisture Content (%) w = [(A-B)/(B-C)] x 100% Weight of Water = A-B Weight of Solids = B-C Topic J
Determining Moisture Content (w)From Lab Test w = [(A-B)/(B-C)] x 100% w = [(100-75)/(75-20)] x 100% w = [25/55] x 100% w = 45.4% Topic J
Determining Moisture Content (w)From Lab Test • See AASHTO page T-99-10 Topic J
Determining Dry Density Proctor Test • Wet Density (W1) = Weight/Volume • Dry Density (W) = Dry Weight of Soil/Volume Topic J
Determining Dry Density Example • Wet Weight of Soil in Mold = 14.81 lbs • Weight of Mold = 10.27 lbs • Volume of Mold = 1/30 cubic foot • Moisture Content of Sample (w) = 5.5% • Dry Density (W) = ? (pounds per cubic feet (pcf)) Topic J
Determining Dry Density Example • W = [W1/(w+100)] x 100 • W = [136.2/(5.5+100)] x 100 • W = 129.1 pcf Topic J
Zero Air Voids Curve • Theoretical Maximum Dry Density (gzav) plotted against corresponding Moisture Content • gzav = gw /(w + 1/Gs) • gw = 62.4 pcf • Gs = 2.65 Topic J
One Point Proctor/Family of Curves • Plot all proctors of likes soils on one graph • Draw curve connecting all of the points of maximum dry density/optimum moisture content. • Find point on each proctor that represents 80% of optimum moisture content. • Draw curve that connects 80% points. Topic J
One Point Proctor/Family of Curves • Perform One Point Proctor (AASHTO T-272) • Plot point obtained for Dry Density and Moisture Content directly on Family of Curves plot. • This point must fall within band from 80% to 100% of optimum moisture content. • If not repeat one point proctor until meeting this requirement, then plot on Family of Curves. Topic J
One Point Proctor/Family of Curves • Draw new proctor curve on Family of Curves that connects through the one point, making the complete curve essentially parallel to the adjacent curves. • New proctor curve can be used to determine percent compaction and percent optimum moisture for representative density test only. • If the one point proctor doesn’t yield accurate point/curve then a full proctor must be performed. Topic J