Implementation and Thickness Optimization of Perpetual Pavements in Ohio

Transcription

1 Implementation and Thickness Optimization of Perpetual Pavements in Ohio OTEC 2015 Issam Khoury, PhD, PE Russ College of Engineering and Technology Ohio University, Athens, Ohio

2 Outline Background prior studies Current study objectives and pavement structure Instrumentation CLV test method CLV test results Conclusions 2

3 Background 3

4 Prior perpetual pavement studies in Ohio STA I77 (2002) 16 in (41 cm) thick 6.0 in (15 cm) DGAB Limited instrumentation WAY 30 (2005) 16 in (41 cm) thick including 4 in (10 cm) FRL 6.0 in (15 cm) DGAB Fully instrumented Field demonstration of perpetual pavement Accelerated Pavement Load Facility (2008) 13 in (33 cm), 14 in (35.5 cm), 15 in (38 cm), 16 in (41 cm) with 4 in (10 cm) FRL in each Perpetual pavement strain criterion maintained at all thicknesses and temperatures Can we do field test of APLF thicknesses? 4

5 Prior project reports available on ODOT website ortsandplans/pages/pavementreports.aspx WAY 30 Perpetual Pavement report titles: Monitoring and Modeling of Pavement Response and Performance: State Job No , Report No. FHWA/OH 2010/3A, Instrumentation of the WAY 30 Test Pavements: State Job No , Report No. FHWA/OH 2008/7 Variable Depth Perpetual Pavement title: Performance Assessment of Warm Mix Asphalt (WMA) Pavements: State Job No , Report No. FHWA/OH 2009/8

6 Pavement Structure 6

7 Implementation and Thickness Optimization of Perpetual Pavements in Ohio Perpetual Pavement Project in Ohio PI: Shad Sargand and Issam Khoury Sponsor: Ohio Department of Transportation Private Sector Partner: Flexible Pavements of Ohio Start date: January 2012 Final Report : May 2015

8 Research Objectives Develop a procedure for the selection of the optimal design for perpetual pavements in Ohio. Investigate various perpetual pavement structure alternatives through varying the thickness and material properties of pavement layers in field test sections. Use data collected at the field test sections to verify the analysis results. Evaluate typical conventional asphalt pavement designs currently used in Ohio and develop an approach to retrofit existing conventional asphalt pavements in good conditions to meet the perpetual pavement requirements

9 Layer Surface Intermediate Base Fatigue Resistance Layer Layer Specifications for Test Sections Description Fine Graded Polymer Asphalt Concrete, PG 76 22M, 7.6% binder content Asphalt Concrete, PG 64 28, 4.9% binder content Asphalt Concrete, PG 64 22, 4.2% binder content Asphalt Concrete, PG 64 22, 4.6% binder content Layer Thickness (in (cm)) 39D168 39P168 39BS803 39BN803 1 (2.5) 1 (2.5) 1 (2.5) 1 (2.5) 2 (5.1) 2 (5.1) 2 (5.1) 2 (5.1) 8 (20.3) 6 (15.2) 6 (15.2) 4 (10.2) 4 (10.2) 4 (10.2) 4 (10.2) 4 (10.2) Total AC thickness (in(cm)) 15 (38) 13 (33) 13 (33) 11 (28) Subgrade stabilization none none lime lime Note: Section 39P168 excluded due to extra thickness at sensors

10 Section locations Section 39BN803: 11 in (28 cm) thickness on NB ramp (red arrow) Lime stabilized subgrade Section 39BS803: 13 in (33 cm) thickness on SB ramp (red arrow) Lime stabilized subgrade Section 39P168: 13 in (33 cm) thickness on passing lane (green arrow) Core samples revealed instrumented area of 39P168 to be 16 in (41 cm) thick. Other areas of section were found to be 13 in (33 cm) thick as designed Section 39D168: 15 in (38 cm) thickness on driving lane (green arrow) Locations of Test Sections (picture by ODOT) 10

11 Pavement Instrumentation 11

12 Instrumentation and measured parameters Weather station: air temperature, rainfall, relative humidity, solar radiation, wind speed, and wind direction Subsurface environmental parameters: Pavement temperature (thermocouples) Load response parameters: Surface and intermediate layer deflections (LVDTs) Horizontal pavement strains (Strain gauges) Subgrade pressure (Pressure cells)

13 Instrumentation Longitudinal and transverse strain gages installed in every asphalt layer except surface Pressure cells installed on subgrade and FRL surfaces Shallow and deep LVDTs Thermocouples installed in every asphalt layer except surface Round (6 in (15 cm) diameter) and square (6 in (15 cm) width) holes constructed with vertical strain gage rosettes installed on parallel and perpendicular (to traffic) faces 2 per face of base layer 1 per face of intermediate layer 1 per face of surface layer (square hole only) All instrumentation is working properly Strain gage installation Lead wire installation Subgrade pressure cell installation Square hole with strain gage rosette 13

14 13 in (33 cm) Section PLAN VIEW Traffic C L Wheel Path Shoulder PROFILE VIEW AC ATB FRL DGAB Subgrade SECTIONS A - B Pressure Cell Linear Variable Displacement Transducer Longitudinal Strain Gage Transverse Strain Gage Strain Gage Rosette

15 15 in (38 cm) Section PLAN VIEW Traffic C L Wheel Path Shoulder PROFILE VIEW AC ATB FRL DGAB Subgrade SECTION C Pressure Cell Linear Variable Displacement Transducer Longitudinal Strain Gage Transverse Strain Gage Strain Gage Rosette

16 Cross sections (Lime stabilized) 13 in (33 cm) Section 39BS in (38 cm) Section 39D168

17 Controlled Vehicle Load (CVL) Test Method 17

18 Controlled Vehicle Load Test 18

19 CVL Testing Summer 2013 Two axle configurations: Tandem axle dual tire Single axle wide based tire Half Axle Loading in kip (kn): Tandem axle load: 10 (44) Single axle load: 10 (44) Varying tire pressures in psi (kpa): 80 (552), 110 (718), and 125 (862) Varying truck speeds in mph (km/h): 5 (8), 35 (58), and 55 (89) Lateral tire offset measured through sand prints Tandem axle dual tire ODOT Truck Lateral tire offset measurement 19

20 Temperatures on test date, July 10, in (28 cm) Section 39BN803 Temperature ( C ) :00 11:00 12:00 13:00 14:00 Time of Day Depth of Sensor (Inches) Air 11" 28 cm 7" 18 cm

21 Temperatures on test date, July 11, in (33 cm) Section 39BS803 Temperature ( C ) :00 11:00 12:00 13:00 14:00 15:00 Depth of Sensor (inches) Time of Day Air 13" 9" 3" 33 cm 23 cm 7.6 cm

22 Temperatures on test date, July 1, in (38 cm) Section 39D168 Temperature ( C ) :00 11:00 12:00 13:00 14:00 15:00 Time of Day Depth of Sensor (Inches) Air 15" 9" 3" 38 cm 23 cm 7.6 cm

23 CVL Test Matrix Truck Type Test Series Axle Type Tire Type Half Axle Load Tire Inflation Pressure (kip) (kn) (psi) (kpa) SW Single Wide Base SW Single Wide Base SW Single Wide Base TD Tandem Dual TD Tandem Dual TD Tandem Dual

24 CVL Test Results

25 Maximum Tensile Strain in FRL 11 in (28 cm) Section Speed 5 mph (8 km/h) 30 mph (48 km/h) 55 mph (89 km/h) Avg Max Avg Max Avg Max Single Axle Wide Base Tire (10 kip (44 kn) Axle Load) SW SW SW Tandem Axle Dual Tire (10 kip (44 kn) Axle Load) TD TD TD

26 Maximum Tensile Strain in FRL 13 in (33 cm) Section Speed 5 mph (8 km/h) 30 mph (48 km/h) 55 mph (89 km/h) Avg Max Avg Max Avg Max Single Axle Wide Base Tire (10 kip (44 kn) Axle Load) SW SW SW Tandem Axle Dual Tire (10 kip (44 kn) Axle Load) TD TD TD

27 Maximum Tensile Strain in FRL 15 in (38 cm) Section Speed 5 mph (8 km/h) 30 mph (48 km/h) 55 mph (89 km/h) Avg Max Avg Max Avg Max Single Axle Wide Base Tire (10 kip (44 kn) Axle Load) SW SW SW Tandem Axle Dual Tire (10 kip (44 kn) Axle Load) TD TD TD

28 Maximum Tensile Strain in FRL Speed 5 mph (8 km/h) Single Axle 80psi 13 inch section 15 inch section 11 inch section Single Axle 110psi Single Axle 125psi Tandem Axle 80psi (1 in = 2.54 cm; 100 psi = 689 kpa) Tandem Axle 110psi Tandem Axle 125psi

29 Maximum Tensile Strain in FRL Speed 30 mph (48 km/h) Single Axle 80psi 13 inch section 15 inch section 11 inch section Single Axle 110psi Single Axle 125psi Tandem Axle 80psi Tandem Axle 110psi Tandem Axle 125psi (1 in = 2.54 cm; 100 psi = 689 kpa)

30 Maximum Tensile Strain in FRL Speed 55 mph (89 km/h) inch section 15 inch section 11 inch section Single Axle 80psi Single Axle 110psi Single Axle 125psi Tandem Axle 80psi Tandem Axle 110psi Tandem Axle 125psi (1 in = 2.54 cm; 100 psi = 689 kpa)

31 Maximum Tensile Strain in FRL 11 in (28 cm) Section Strain (με) SW SW SW TD TD TD mph 30 mph 55 mph 8 km/h 48 km/h 89 km/h

32 Maximum Tensile Strain in FRL 13 in (33 cm) Section Strain (με) SW SW SW TD TD TD mph 30 mph 55 mph 8 km/h 48 km/h 89 km/h

33 Strain (με) Maximum Tensile Strain in FRL 15 in (38 cm) Section 5 mph 30 mph 55 mph 8 km/h 48 km/h 89 km/h SW SW SW TD TD TD

34 Single Axle Wide base Tire vs Tandem Axle 11 in (28 cm) Section Tire Pressure Single Axle Widebase Tire Dual Tire Axle strain Tandem Axle Tandem Axle strain/single (psi) (kpa) 5 mph (8 km/h) % % % 30 mph (48 km/h) % % % 55 mph (89 km/h) % % % Avg 74.96%

35 Single Axle Wide base Tire vs Tandem Axle 13 in (33 cm) Section Tire Pressure Single Axle Widebase Tire Dual Tire Axle strain Tandem Axle Tandem Axle strain/single (psi) (kpa) 5 mph (8 km/h) % % % 30 mph (48 km/h) % % % 55 mph (89 km/h) % % % Avg 75.03%

36 Single Axle Wide base Tire vs Tandem Axle 15 in (38 cm) Section Tire Pressure Single Axle Widebase Tire Dual Tire Axle strain Tandem Axle Tandem Axle strain/single (psi) (kpa) 5 mph (8 km/h) % % % 30 mph (48 km/h) % % % 55 mph (89 km/h) % % % Avg 73.58%

37 Effect of Tire Pressure 11 in (28 cm) Section Axle/tire Single Axle Wide Base Tandem Axle Dual Tire % change from 80 psi Maximum strain (με) (552 kpa) value 80 psi 110 psi 125 psi 110 psi 125 psi Speed (552 kpa) (758 kpa) (862 kpa) (758 kpa) (862 kpa) 11 in (28 cm) section 5 mph (8 km/h) % 3.71% 30 mph (48 km/h) % 4.95% 55 mph (89 km/h) % 22.96% 5 mph (8 km/h) % 12.27% 30 mph (48 km/h) % 13.33% 55 mph (89 km/h) % 0.38%

38 Effect of Tire Pressure 13 in (33 cm) Section Axle/tire Single Axle Wide Base Tandem Axle Dual Tire % change from 80 psi Maximum strain (με) (552 kpa) value 80 psi 110 psi 125 psi 110 psi 125 psi Speed (552 kpa) (758 kpa) (862 kpa) (758 kpa) (862 kpa) 11 in (28 cm) section 5 mph (8 km/h) % 14.55% 30 mph (48 km/h) % 9.08% 55 mph (89 km/h) % 18.51% 5 mph (8 km/h) % 12.56% 30 mph (48 km/h) % 16.42% 55 mph (89 km/h) % 16.77%

39 Effect of Tire Pressure 15 in (38 cm) Section Axle/tire Single Axle Wide Base Tandem Axle Dual Tire % change from 80 psi Maximum strain (με) (552 kpa) value 80 psi 110 psi 125 psi 110 psi 125 psi Speed (552 kpa) (758 kpa) (862 kpa) (758 kpa) (862 kpa) 11 in (28 cm) section 5 mph (8 km/h) % 6.10% 30 mph (48 km/h) % 8.77% 55 mph (89 km/h) % 0.79% 5 mph (8 km/h) % 7.60% 30 mph (48 km/h) % 5.24% 55 mph (89 km/h) % 19.31%

40 APLF Tests (2013) 40

41 Test Sections 8, 9, 10, and 11 inches of AC Cement Stabilized subgrade to 18 inches Highly Modified Asphalt (HiMA) by Kraton Polymers. Tested at two temperatures: 40F and 100F Each lane subjected to 10,000 passes (9000 lb wheel load) at each temperature 41

42 APLF Test Section Data Collected Temperature Profiles Deflection Measurements Strain (Longitudinal and Transverse) Profiles ( To measure surface rutting performance) 42

43 Rut Depth vs Number of Passes ODOT has four classifications for rutting: High, medium, low and none. Rut values did not exceed low threshold of in. Temp 100 F 43

44 Endurance Limit 44

45 Stiffness Ratio Equation NCHRP Project 9 44 SR= *log(E0 ) *log(εt ) *log(n) *tanh(0.8471*rp) *log(e0 )*log(εt ) *log(e0 )*tanh(0.7154*rp) *log(εt ) *tanh(0.6574*rp) *log(n)*log(e0 ) *log(N) *log(εt ) *log(N)*tanh(0.2590*RP) Where: SR=Stiffness Ratio E0=Initial Flexural Stiffness (ksi) εt=applied Tensile Strain (με) RP=Rest Period (seconds) N=Number of Loading Cycles 45

46 Effect of Initial Flexural Stiffness (E0) As the stiffness decreases, the endurance limit increases (mix is more ductile) As the stiffness increases, the endurance limit decreases (mix is more brittle) The value of E0 is dependent on the temperature (higher temperature = lower E0 and vice versa) 46

47 Measuring Initial Flexural Stiffness (E0) Dynamic modulus (E*) was used to estimate E0. The NCHRP Design Guide assumes that the dynamic modulus is equal to the initial flexural stiffness (E0 = E*). Kansas researchers found that the dynamic modulus is about 2 times the amount of the initial flexural stiffness (E0 = E*/2). Kansas researchers also state that the frequency of the dynamic modulus that was used for comparison was 10 Hz. Both assumptions were used to compare the various endurance limits for this analysis (E0 = E* and E0 = E*/2) at a loading frequency of 10 Hz for the dynamic modulus. 47

48 Comparison of Endurance Limits and Strain Results from Field Testing Asphalt Base layer mixtures were used to compare endurance limits with field strain measurements Temperature ( F) Dynamic Modulus at 10 Hz (ksi) DEL 23 FRL HiMA AC Base (Kraton) AC Base Control

49 Dynamic Modulus Regression Results Temperatures tested from the field had to be normalized with laboratory tested dynamic modulus temperatures using a 2nd order polynomial function for each mix that was used: E* (T)=aT 2 +bt+c Where: T = Test Temperature ( F) a, b, c = Regression Coefficients AC Base Mix Regression Coefficients a b c R 2 DEL 23 FRL HiMA AC Base (Kraton) AC Base Control

50 Comparison of Endurance Limits and Strain Results from Field Testing DEL 23 when E0 = E* DEL 23 Stiffness Ratio Based on the Average Peak Strain Measured During the Controlled Vehicle Load Tests (E0 = E*) RP=5 seconds, f=10hz, N=200,000, SR=1 Date Lane Pavement Depth Avg. Temp Initial Flexural Stiffness Stiffness Ratio Avg. Peak Strain FEL (in) T ( F) E 0 (ksi) SR ε t (10 6 in/in) ε t (10 6 in/in) 11/29/2012 D /18/2012 N /19/2012 S /1/2013 D /10/2013 N /11/2013 S

51 Comparison of Endurance Limits and Strain Results from Field Testing DEL 23 when E0 = E*/2 DEL 23 Fatigue Endurance Limit at Test Temperatures (E0 = E*/2) RP=5 seconds, f=10hz, N=200,000, SR=1 Date Lane Pavement Depth Avg. Temp Dynamic Modulus Initial Flexural Stiffness FEL (in) T ( F) E* (ksi) E 0 (ksi) ε t (10 6 in/in) 11/29/2012 D /18/2012 N /19/2012 S /1/2013 D /10/2013 N /11/2013 S

52 HiMA Results HiMa When E0=E* HiMA Stiffness Ratio Based on the Average Peak Strain Measured During the Controlled Vehicle Load Tests (E0 = E*) RP = 5 seconds, f = 10 Hz, N = Lane Mix Pavement Thickness Test Temp Dynamic Modulus Initial Flexural Stiffness Stiffness Ratio Avg. Max Strain FEL (in) T ( F) E* (ksi) E 0 (ksi) SR ε t (10 6 in/in) ε t (10 6 in/in) D C B A AC Base: Control AC Base: Kraton AC Base: Kraton AC Base: Kraton

53 HiMA Results HiMa When E0=E*/2 HiMA Stiffness Ratio Based on the Average Peak Strain Measured During the Controlled Vehicle Load Tests (E0 = E*/2) RP = 5 seconds, f = 10 Hz, N = Lane Mix Pavement Thickness Test Temp Dynamic Modulus Initial Flexural Stiffness Stiffness Ratio Avg. Max Strain (in) T ( F) E* (ksi) E 0 (ksi) SR ε t (10 6 in/in) FEL ε t (10 6 in/in) D AC Base: Control C AC Base: Kraton B AC Base: Kraton A AC Base: Kraton

54 Conclusions 54

55 Conclusions DEL 23 All the data obtained from DEL 23 for all the loading conditions, speed, climate conditions, including worst case conditions, such as 5 mph (8 km/h) traffic under high temperature, were analyzed in conjunction with the NCHRP 9 44A endurance limit model. The 13 in thick (33 cm) or greater, constructed on a 6 in (15 cm) aggregate base and stabilized subgrade, met criteria for perpetual pavement, The 11 in (28 cm) section on the same base and subgrade did not. A pavement thickness of 15 in (38 cm) or greater, constructed on an aggregate base and compacted subgrade, also met perpetual pavement criteria. The worst case test conditions, 5 mph (8 km/h) heavy load will not produce a major discrepancy with static load. These conditions may lead to rutting in the surface course, but the rutting will be minimal in the base and stabilized subgrade due to their enhanced stiffness

56 Conclusions APLF Tests Test lanes were constructed in the Accelerated Pavement Load Facility (APLF) which further evaluated thicknesses and included the use of highpolymer content binder, or highly modified asphalt (HiMA). On the builtup sections in the indoor facility, subgrade was stabilized, moisture increase in the subgrade soil typically experienced in the field did not occur, and construction quality was very high. In the APLF, based on data collected, all sections satisfied NCHRP Project 9 44A criteria for perpetual pavement (Witczak et al, 2013). The 8 in (20 cm) thick well constructed HiMA pavement on 304 and stabilized subgrade met perpetual pavement criteria in the highly controlled environment of the APLF. Very little rutting was observed in the test pavements. Comparing HiMA with control sections there was significant improvement in rutting resistance using the high polymer asphalt

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