Subgrade Soil Support and Stabilization

Transcription

1 Subgrade Soil Support and Stabilization O HARE Airport Modernization Research Project Research Progress Presentation June 30, 2005 Co-PIs: Erol Tutumluer Marshall R. Thompson RA: H.S. Brar

2 Introduction Subgrade performance is a key factor in the overall pavement performance P209 P154 National Airport Pavement Test Facility - Atlantic City, NJ This project provides testing and analysis to establish subgrade support and stabilization requirements for O Hare airport pavements

3 Introduction (cont d) The preliminary concrete pavement design for the O Hare Modernization Program (OMP): inches of PCC Surface 6-inch Hot Mix Asphalt Base 6-inch Asphalt Treated Permeable Base (!?) Stabilized Subgrade Zone (SSZ) Prepared Subgrade North Runway (9L-27R, 7,500 ft) paving is scheduled first for the Spring 2006 (!?) Stockpiles of local soil on runway centerline (excavated from the Deep Pond nearby) Primarily fill and cut areas

4 Research Objectives Consider pavement design inputs for subgrade support Modulus of subgrade reaction, k Consider subgrade support and stabilization requirements with respect to: Need for subgrade stabilization Stabilization admixture(s) stabilization Stabilization depth Estimate subgrade support for various combinations of subgrade stabilization treatments and prepared subgrade conditions

5 Project Tasks Task 1: Establish the Best Demonstrated Available Technology (BDAT) for subgrade soil evaluation and stabilization (Ongoing) Reports and publications collected & submitted as Technical Notes on: Subgrade strength/stiffness evaluation techniques Subgrade stability requirements & IDOT Manual Working platform requirements for pavement construction

6 Project Tasks Task 2: Evaluate currently available data for the subgrade test sections constructed in the Fall of 2003 and the necessity/usefulness of constructing additional subgrade treatment test sections at O Hare (Effort completed) Plate load tests conducted (8/04) on the test sections: Plate 1: 12-inch stabilization/compaction no admixture Plate 2: 12-inch quicklime fine (40 lb/yd 2 ) & fly ash (80 lb/yd 2 ) stabilization Plate 3: 12-inch quicklime fine stabilization (40 lb/yd 2 ) Plate 4: 12-inch lime kiln dust stabilization (40 lb/yd 2 )

7 Modulus of Subgrade Reaction, k Plate Load Tests

8 Project Tasks Task 3: Advise OMP on current and future test section monitoring and field test evaluation programs (Effort completed) Various field tests may be useful to characterize the treated subgrade (OMP will arrange for testing): Dynamic Cone Penetrometer (8/04) Light-Weight Deflectometer (8/04) Clegg Hammer Geogauge Heavy Weight Deflectometer (HWD) Ground Penetrating Radar (GPR) Seismic Pavement Analyzer, SASW, etc.

9 Light-Weight Deflectometer Dynamic Cone Penetrometer

10 Project Tasks Task 4: Evaluate currently available geotechnical/subgrade data for the North Runway with emphasis on the stockpiled Deep Pond soils. Recommend further soil sampling & testing to be conducted (by an OMP designated testing firm) (Ongoing) Routine tests to establish representative soils existing for the runway subgrade Grain size distribution (including hydrometer) Atterberg limits (LL and PL for PI) Moisture-density-CBR PH value & calcareous content If needed, organic matter content

11 Preliminary Geotechnical Report Soil sampling & testing conducted by Everest Engineering on OMP Runway 9L-27R - October 2004 Atterberg limits (LL and PL for PI) Boring Logs

12 Preliminary Geotechnical Report Soil sampling & testing conducted by Everest Engineering on OMP Runway 9L-27R - October 2004 Grain size distribution (including hydrometer)

13 Preliminary Geotechnical Report Soil sampling & testing conducted by Everest Engineering on OMP Runway 9L-27R - October 2004 Moisture-density-CBR

14 Preliminary Geotechnical Report Soil sampling & testing conducted by Everest Engineering on OMP Runway 9L-27R - October 2004 Unconfined Compressive Strength, Qu

15 Soil Sampling: Dec. 04 Feb. 05 Current scheduled soil sampling & testing from the R9L-27R The Drilling Program Auger borings, 17 boreholes, MT-1 to MT to 45 depths through fill & cut areas All reaching down to elev. 640 in the natural subgrade 3 North of runway, 3 North edge of runway, 4 under runway, 2 South edge of runway, 2 between runway and taxiway, and 3 under taxiway SPT and soil sampling at 2.5 Moisture content, LL, PI, grain size distribution (%clay) Shelby tube samples at each location (638 to 642 ) At least 1 bucket for each major soil in each borehole Two 5-gallon buckets (60-70 lbs./bucket) for each representative soil (composite sample) to test at the University of Illinois

16 Project Tasks Task 5: Based on the data and information gathered in Task 4, select (in consultation with OMP) the identified representative soils and recommend an admixture stabilization program (Ongoing) Tests to be conducted at the UIUC Advanced Transportation Research and Engineering Laboratory (ATREL) on both untreated & treated soils Moisture-Density-CBR Unconfined Compressive Strength Resilient Modulus Permanent 6-psi deviator stress

17 Project Challenges Proper sampling of the R9L-27R stockpiled soils Selecting & identifying representative soil samples Adequately characterizing the representative soil samples by conducting tests at the UIUC ATREL for Moisture-Density-CBR Unconfined Compressive Strength Resilient Modulus Permanent 6-psi deviator stress

18 University of Illinois Laboratory Testing Program at ATREL Advanced Transportation Research & Engineering Laboratory (ATREL)

19 62 Buckets of OMP Soils Arrived at ATREL from the Drilling Program Location Bucket No. Depth Soil Description % Clay LL PI MARCH 2005 % Silt ph Carbonate Reaction Under N edge of Taxiway 48 6'-10' Gray SILTY SAND 11.9 NP NP Weak North of Runway 1 1'-3' Brown Sandy Silt 16 NP NP weak to strong Under Taxiway 57 15'-18' Gray SILTY SAND 17.4 NP NP Weak N edge of Runway 20 5'-10' Gray SILTY CLAY with Sand Strong Under Taxiway 53 22'-26' Gray SANDY SILT 18.3 NP NP Weak North of Runway 17 1'-5' Brown and Gray SANDY LEAN CLAY Weak to Strong Under Runway 13 3'-6' Gray SANDY SILT CLAY Weak to Strong Under S edge of Runway 43 1'-4' Gray LEAN CLAY with sand Strong Under N edge of Runway 49 24'-28' Gray LEAN CLAY with sand Strong Under Taxiway 54 29'-33' Gray SANDY LEAN CLAY Strong North of Runway 9 3'-6' Brown and Gray SANDY LEAN CLAY Weak to Strong North of Runway 2 6'-10' Gray SANDY LEAN CLAY Weak Under Taxiway 52 6'-10' Gray SANDY LEAN CLAY Strong Under Taxiway 51 2'-6' Gray LEAN CLAY with sand Strong b/w Runway & taxiway 41 16'-20' Gray SANDY LEAN CLAY Weak to Strong Under S edge of Runway 44 8'-12' Gray SANDY LEAN CLAY Strong Under N edge of Runway 5 1'-5' Brown and Gray LEAN CLAY with Sand Weak to Strong Under N edge of Taxiway 50 33'-36' Gray SANDY LEAN CLAY Weak Under Runway 22 1'-5' Brown and Gray LEAN CLAY with Sand Weak to Strong b/w Runway & taxiway 42 26'-30' Gray LEAN CLAY with sand Strong North of Runway 11 16'-20' Gray LEAN CLAY with Sand Weak

20 62 Buckets of OMP Soils Arrived at ATREL from the Drilling Program- cont d Location Bucket No. Depth Soil Description % Clay LL PI MARCH 2005 % Silt ph Carbonate Reaction North of Runway 18 18'-23' Gray LEAN CLAY with sand Strong Under S edge of Runway 28 1'-5' Gray LEAN CLAY with Sand Strong North of Runway 10 8'-12' Gray LEAN CLAY with Sand Strong Under S edge of Runway 45 24'-28' Gray LEAN CLAY with sand Strong Under S edge of Runway 29 13'-18' Gray LEAN CLAY with Sand Strong Under Runway 33 8'-12' Gray LEAN CLAY with Sand Strong b/w Runway & taxiway 39 2'-6' Gray SANDY LEAN CLAY Strong Under Runway 26 0'-3' Black,Brown and Gray SANDY LEAN CLAY Weak b/w Runway & taxiway 40 8'-12' Gray LEAN CLAY with sand Strong Under N edge of Taxiway 47 1'-5' Gray LEAN CLAY with sand Strong Under Runway 32 1'-5' Gray LEAN CLAY with Sand Strong b/w Runway & taxiway 36 1'-5' Gray LEAN CLAY with Sand Strong Under Runway 14 10'-15' Gray LEAN CLAY with sand Strong North of Runway 3 16'20' Gray LEAN CLAY with sand Strong b/w Runway & taxiway 37 15'-20' Brown and Gray SANDY LEAN CLAY Strong Under S edge of Runway 30 28'-32' Gray LEAN CLAY with Sand Strong Under N edge of Runway 6 11'-15' Gray LEAN CLAY with sand Strong Under Runway 23 10'-13' Brown and Gray LEAN CLAY with Sand Strong North of Runway 19 28'-33' Brown and Gray LEAN CLAY with Sand Weak Under Runway 34 24'-28' Gray LEAN CLAY with Sand Strong b/w Runway & taxiway 38 25'-30' Gray LEAN CLAY with Sand Strong North of Runway 4 22'-27' Gray LEAN CLAY with sand Weak

21 Grouping of Soils at ATREL Boring No. Bucket No. Depth Soil Description Clay (%) LL (%) PI (%) Silt (%) GROUP 1 MT '-10' Gray SILTY CLAY with Sand MT '-5' Brown and Gray SANDY LEAN CLAY MT '-4' Gray LEAN CLAY with sand MT '-33' Gray SANDY LEAN CLAY GROUP 2 MT '-10' Gray SANDY LEAN CLAY MT '-6' Gray LEAN CLAY with sand MT '-12' Gray SANDY LEAN CLAY MT '-36' Gray SANDY LEAN CLAY Grouping done primarily according to % clay content!..

22 Grouping of Soils at ATREL Boring No. Bucket No. Depth Soil Description Clay (%) LL (%) PI (%) Silt (%) GROUP 3 MT '-5' Gray LEAN CLAY with sand MT '-5' Gray LEAN CLAY with Sand MT '-5' Gray LEAN CLAY with Sand MT '-20' Gray LEAN CLAY with sand MT '-21' MT '-34' MT '-35' MT '-10' GROUP 4 Brown and Gray LEAN CLAY with Sand Brown and Gray LEAN CLAY with Sand Brown and Gray LEAN CLAY with Sand Brown and Gray LEAN CLAY with Sand

23 Admixture Types / Sources Carmeuse (potential supplier) South Chicago (dolomitic lime) Buffington, IN (high calcium lime) Lime types Lime Kiln Dust (LKD) Quicklime fines so far used in lime treatment Buffington is the primary source (We will work with this & confirm with S. Chicago)

24 Test Specimen Preparation Air Drying Pulverizing Mixing

25 Moisture- Density- CBR Results CBR (ASTM D1883) Proctor Compaction (ASTM D698, D1557) Untreated

26 Group 1 Results Moisture-Density 0 % Lime 5 % Lime W (%) Dry Density ( pcf ) W (%) Dry Density ( pcf )

27 Group 1 Results California Bearing Ratio (CBR) 0 % Lime 5 % Lime W (%) CBR W (%) CBR

28 Group 1 Results CBR OMC=13.8% OMC=12.1% % Lim e 5% Lime Moisture % 125 OMC=12.1% 120 OMC=13.8% Density (pcf) % Lime 5% Lime Moisture %

29 Group 2 Results Moisture-Density 0 % Lime 5 % Lime W (%) Dry Density ( pcf ) W (%) Dry Density ( pcf )

30 Group 2 Results California Bearing Ratio (CBR) 0 % Lime 5 % Lime W (%) CBR W (%) CBR

31 Group 2 Results 60 CBR OMC = 16% OMC = 14.1% Dry Density (pcf) OMC =14.1% 120 OMC=16% % Lime 5% Lime Moisture Content %

32 Group 3 Results Moisture-Density 0 % Lime 5 % Lime W (%) Dry Density ( pcf ) W (%) Dry Density ( pcf )

33 Group 3 Results California Bearing Ratio (CBR) 0 % Lime 5 % Lime W (%) CBR W (%) CBR

34 Group 3 Results CBR OMC=14.4 % OMC=18.8 % 0% Lime 5% Lime OMC=14.4 % Density (pcf) OMC=18.8 % 0% Lime 5% Lime Moisture Content %

35 Group 4 Results Moisture-Density 0 % Lime 5 % Lime W (%) Dry Density ( pcf ) W (%) Dry Density ( pcf )

36 Group 4 Results California Bearing Ratio (CBR) 0 % Lime 5 % Lime W (%) CBR W (%) CBR

37 Group 4 Results CBR OMC = 18.8 % OMC= 18.8 % OMC= 22.8 % % Lim e 5% Lime Density (pcf) OMC = 22.8 % 0% Lime 5% Lime Moisture %

38 Unconfined Compressive Strength Test Results τ σ d = σ 1 σ 3 (=0) failure C = (σ 1f )/2 = Q u /2 σ 3 = 0 σ 1 σ 1f σ Cohesive Soils (c, φ=0) (ASTM D2166)

39 UCS without Lime Group No. OMC (%) Water Content (%) Dry Density (pcf) UCS (psi)

40 UCS Without Lime Group 1 Group 2 Group 3 Group 4 Axial Stress, psi Axial Strain, %

41 UCS with 5% Lime Group No. OMC (%) Sample No. Water Content (%) Dry Density ( pcf ) UCS (psi) Avg. UCS (psi)

42 Group 1 with 5% Lime Axial Stress, psi Sample 1 Sample 2 Sample Axial Strain, %

43 Group 4 with 5% Lime Sample 1 Sample 2 Sample 3 Axial Stress, psi Axial Strain, %

44 Lime Reactivity Group No. UCS with Lime Q u lime (psi) UCS without Lime Q u (psi) Lime Reactivity = (Q u lime - Q u ) (psi)

45 Resilient Modulus (M R ) Testing σ d Unconfined: σ 3 = 0 2-in. in φ M R = resilient modulus = σ d / ε r σ d : Deviator stress ε r : recoverable strain Conditioning: 200 load applications at σ 3 = 0, σ d = 41 kpa Testing: 100 load applications σ d = 14, 28, 41, 55, 69, 83, 96, 110 kpa

46 M R Tests Soil Samples Cylindrical specimens, 2 in. φ by 4 in. high Undisturbed soil samples Shelby tube (φ = 2.8, 4 in.)

47 Typical M R Characterization 28 Greensboro, NC Airport Subgrade Soils M R = σ d R 2 = RESILIENT MODULUS M R (ksi) A-4 soil at OMC A-4 soil at OMC+3 M R = σ d R 2 = Bilinear or Arithmetic Model 4 M R = σ d M R = σ d R 2 = R 2 = APPLIED DEVIATOR STRESS σ d (psi)

48 Group 1 M R Test Results Resilient modulus, ksi Eri Deviator Stress, psi

49 Group 2 M R Test Results Resilient modulus, ksi Eri Deviator Stress, psi

50 Group 3 M R Test Results Resilient modulus, ksi Eri Sample Deviator Stress, psi

51 Group 3 M R Test Results Resilient modulus, ksi Eri Sample Deviator Stress, psi

52 Group 4 M R Test Results Resilient modulus, ksi Eri Sample Deviator Stress, psi

53 Group 4 M R Test Results Sample 2 Resilient modulus, ksi Eri Deviator Stress, psi

54 Summary of Results (1) Moisture Density CBR Tests: Optimum moisture contents of the natural soils were always lower those of the same soils treated with 5% lime kiln dust (LKD) Similarly, maximum dry densities were always higher for the natural soils without lime treatment The unsoaked CBR values obtained from testing the compacted specimens tend to drop sharply after the optimum moisture contents for the soils without lime The treated soils with 5% lime always gave much higher unsoaked CBR values than the natural soils with no lime In general, the 5% lime treatment was effective for increasing sufficiently the strength of the North Runway 9L-37R subgrade soils tested

55 Summary of Results (2) Unconfined Compressive Strength Tests: Large increases in unconfined compressive strengths observed for all groups when 5% lime was added Lime reactivity (Qu lime treated Qu natural) is greater than 50 psi for all the groups except for Group 1 Minimum lime treated Qu = 119 psi was recorded for Group 1 soils with the lowest clay contents & the least reactivity with lime Resilient Modulus (M R ) Tests: M R decreased with increasing applied deviator stresses; typical stress-softening fine grained soil behavior All soil groups tested at the OMC gave high M R values at 6 psi deviator stress, in the range of Eri = ksi

56 Conclusion From the results of all tests performed, Green Light is given to the 5% lime kiln dust treatment which seems to be working quite well in increasing the soil strengths and, therefore, is suggested as the stabilization choice for the subgrade soils at the new North Runway 9L-27R of O Hare International Airport

57 Project Deliverables Technical Notes have been prepared and submitted to the OMP throughout the project duration to communicate specific findings and recommendations to OMP engineers TN5: K-150 Considerations for RW 9-27 TN6: Subgrade Strength/Stiffness Evaluation TN7: Working Platform Requirements for Pavement Construction TN8: Subgrade Stability Manual (IDOT) TM13: Moisture Limitations for Lime Stabilization TN14: Admixture Stabilization (Lime Treatment of Subgrades) Several of the Project Tasks have been pursued simultaneously and coordinated with OMP A Report summarizing Laboratory Soil Test Program has been prepared. More soil-lime testing will be conducted with different lime sources A Final Report will be prepared at the end of the one-year study (September/October 2005) We will continue to work with OMP on future subgrade soil support and stabilization needs for other runways/taxiways