Evaluation of Subbase Compaction Characteristics Craig Kumpel Andrew Melici Stephen Rossi Colin Yurick Dr. Beena Sukumaran FAA Working Group Meetings,

Evaluation of Subbase Compaction Characteristics

Craig KumpelAndrew MeliciStephen RossiColin YurickDr. Beena Sukumaran

FAA Working Group Meetings, April 25, 2012

• Background and Objectives

• P-154 Test Results

• P-209 Test Results

• DGA Test Results

• Correlation of lab results with field data

• Conclusions

Outline


Background

• Continuous loading from airplane landing gear creates ruts in pavement

• Bigger and heavier planes with complex gear configurations make rut prevention more difficult

• FAA believes rutting at the National Airport Pavement Test Facility (NAPTF) for the chosen pavement configurations subjected to heavy aircraft loads is caused by densification of subbase


NAPTF – Rutting Behavior

North wheel track of CC3 flexible pavements at 19,500 passes

Garg and Hayhoe (2006)


CC5 Trench Cross Section


Objectives

• Determine the correlation between trafficking passes of various aircrafts/construction equipment and number of gyrations in the SGC

• Determine the change in the performance metrics (includes shape and angularity of particles, as well as gradation) of the unbound aggregate when it is subjected to trafficking/gyrations in the SGC

• Determine the mechanism that is causing compaction of the unbound aggregate during trafficking


Gyratory Compactor and Soil Parameters


• Angle Used: 1.25°

• Pressure Used: 600, 800 and 1000 kPa

• # of Gyrations: 800

• Sample Size: 3000 grams

•Water Content Ranges:2-2.5%, 2.5-3%, 3-3.5%, 3.5-4%, 4-5%, 5-6%

P-154


P-209


DGA


1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.52000

2050

2100

2150

2200

2250

Modified Proctor

1000 kPa

800 kPa

600 kPa

5000 gram, 800 kPa

Moisture Content (%)

Den

sity

(kg/

m3)

SGC Density at 800 gyr. and Modified Proctor Data



1 2 3 4 5 6 7145

147

149

151

153

155

157

159

161

163

165

SGC Density at 800 gyr. and Modified Proctor data for P-209

Modified Proctor

800 kPa

1000 kPa

600 kPa


Den

sity

(pcf

)


1 2 3 4150

152

154

156

158

160

162

164

SGC Density at 800 gyr. and Modified Proctor data for DGA

Modified Proctor

800 kPa

1000 kPa

600 kPa


Den

sity

(pcf

)

SGC vs. Proctor Tests

• Energy input from Proctor tests come from impact hammer (all vertical work)

• The SGC can achieve higher densities than the impact hammer alone

• The energy input from the SGC comes from:– Vertical load applied– Shearing caused by the gyratory movement– Energy input more efficient at achieving similar

densitiesFAA Working Group Meetings, April 25, 2012

MDD Placement in P-154


P-154 Comparison of Field and SGC Compaction

0 2000 4000 6000 8000 10000 12000 14000

0 2000 4000 6000 8000 10000 12000 14000

-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0

MDD-3AMDD-5A1000 kPa Test 11000 kPa Test 21000 kPa Test 5

Event Number

Disp

lace

men

t (in

)

Gyration Number


MDD Placement in DGA


DGA Comparison of Field and SGC Compaction0 2000 4000 6000 8000 10000 12000 14000

0 2000 4000 6000 8000 10000 12000 14000

-1.4

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

MDD-9AMDD-11A800 kPa Test 1800 kPa Test 2800 kPa Test 3

Event Number, Gyration Number

Dis

plac

emen

t (in

)


P-154 Grain Size Distribution Analysis


0.010.11101000%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Untrafficked

Compacted (3200 gyr.)

North Trafficked (6 Wheel)

South Trafficked (4 Wheel)

Diameter (mm)

Pass

ing

Perc

enta

ge

P-209 Grain Size Distribution Analysis


0.010.11101000%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Untrafficked

Compacted

North Trafficked (6 Wheel)

South Trafficked (4 Wheel)

Diameter (mm)

Pass

ing

Perc

enta

ge

DGA Grain Size Distribution Analysis

0.010.11101000%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

UntraffickedCompacted

Diameter (mm)

Pass

ing

Perc

enta

ge


Mechanism of Compaction

Different modes of grain breakage: a) fracture, b) attrition and c) abrasion. (Ramamurthy et al., 1974)


P-154 Construction to SGC Correlation

0 1 2 3 4 5 6 7

0 2 4 6 8 10 12 14

788082848688909294

8081828384858687888990

Lift #1

SGC 800 kPa

Number of Passes

Mod

ified

Pro

ctor

Per

cent

age

Gyration Count

0 2 4 6 8 10 12 14

0 5 10 15 20 25 30 35 40

75

80

85

90

95

100

76788082848688909294

Lift #5

SGC 800 kPa

Number of PassesM

odifi

ed P

roct

or P

erce

ntag

e

Gyration Count


Number of Passes/Gyrations for Modified Proctor Density

D50 < 5mm D50 > 5mm

Steel Vibratory Roller

Rubber Tire/Steel Roller

Steel Vibratory Roller Rubber Tire/Steel

Roller

Gyrations Passes Gyrations Passes Gyrations Passes Gyrations Passes

2 1 2.5 1 - - - -*Gyrations based upon 800 kPa confining pressure on a 3000 gram sample.

*3000 gram sample translates to a 4 inch lift height

Percent Modified Proctor vs Gyrations - P-154

Average Moisture (%) 2-2.5 2.5-3 3-3.5 3.5-4

% Max Mod. Proctor

80 - 85% 2 3 4 4

85 - 90% 7 11 11 10

90 - 95% 43 44 42 37

95 - 100% 438 436 396 283

>100% - - 762 654

Field To Lab Correlation


•800 kpa was used based on past results showing its similarity to field measurements

Conclusions• SGC is capable of replicating field compaction results

– Capable of achieving much higher densities than the Modified Proctor test

– SGC density results follow the same trend of the Modified Proctor test

– SGC reaching construction densities at relatively low gyration counts• Compaction mechanism for trafficking is attrition and abrasion

– Reduces angularity and therefore interlock– SGC follows same mechanism of compaction as trafficking– SGC was able to produce a similar amount of aggregate crushing in

comparison to trafficked material• Done by compacting to final maximum densities provided by the

FAA


Acknowledgments

• The work described in this presentation was supported by the FAA Airport Technology Research and Development Branch, AJP-6310, Dr. Satish K. Agrawal, Manager, under Grant #11-G-008. The contents of the presentation reflect the views of the authors, who are responsible for the facts and accuracy of the data presented within. The contents do not necessarily reflect the official views and policies of the FAA. The presentation does not constitute a standard, specification, or regulation.


Documents

Evaluation of Subbase Compaction Characteristics Craig Kumpel Andrew Melici Stephen Rossi Colin Yurick Dr. Beena Sukumaran FAA Working Group Meetings,