Damage Factor Assessment through Measuring Direct Response of - PowerPoint PPT Presentation

Damage Factor Assessment through Measuring Direct Response of Asphalt Pavement due to Heavy Loading A’arif Hamad-MSc. Candidate Dr. Lynne Cowe Falls- Supervisor

CONTENTS � Introduction � Background � Objective of Study � Methodology � Preliminary Results � Conclusions and Suggestions for Future Work

INTRODUCTION � Low Volume Roads Under Heavy Loading 1. Low traffic volume 2. Structurally under-designed roads � Road Authorities and Restrictions on Roads 1. Seasonal ban (thaw season) 2. Maximum allowable axle loading � Load Equivalency Factors (LEFs) 1. AASHTO test road 2. Common vehicle configuration

TAC Recom. Max. Axle Wt. Tonnes Kips Steering 5.50 12.1 Single 9.10 20.1 Tandem 17.00 37.5 Tridem 21.00 46.3 23.00 50.7 24.00 52.9

Heavy Vehicle Under Study

Differences From Traditional Loading • Four Adjacent Axles • Axle Loads Exceed the Recommended Limits • Super Single Tires • Hydraulic Suspension System Axle 1- kg Axle 2- kg Axle 3- kg Axle 4- kg Total- kg (Kips) (Kips) (Kips) (Kips) (Kips) 11,700 12,400 10,650 9,200 43,950 (25.8) (27.3) (23.4) (20.3) (96.8)

Motivation For This Study • Winter Season • Average Two Moves in a Month • Moving Crane on Four Axles Without Using Extra Dollies • Money Saved ?

BACKGROUND 1. Christison et al.1978 � Various axle configurations (single on dual tires, single on single tires, tandem on dual tires, and single on single tires for self- propelled earthmovers. � Wide range of axle loads for each axle type. � Instrumented two Alberta standard full depth asphalt concrete pavements (200 & 280 mm).

BACKGROUND � The study results related the interfacial strains and surface deflections to several factors (pavement age, pavement temperature, and vehicle velocity). � Calculated LEFs based on different concepts (surface deflection, flexural distress. Also proved agreement of calculated LEFs with the pavement performance according to AASHTO test road.

BACKGROUND 2. Christison 1990 � Investigated two cranes with heavy axle loads (total wt.590 & 627 kN respectively). � Instrumented two asphalt concrete roads in Alberta each with 135 mm ACP layer on two different base layers. � LEF’s values ranging from 5.2 to 26.8 were found in the study for the cranes. � LEFs were related to pavement structure, Crane type, traveling speed,and concept for LEFs calculation.

OBJECTIVE OF STUDY � Study the Effect of Heavy Loading on Thin Membrane Flexible Pavement � Update Historical Data (LEFs, Dynamic loading, Seasonal factors) � Develop New Performance Models � Evaluate New Technologies and Equipment (Super singles, CTI) � Update/Validate Existing Road User Regulations

METHODOLOGY A. Field Test i. Construction and instrumentation of a test road ii. Conducting a series of tests using the heavy loads and standard load iii. Analyzing data and find results B. Finite Element Analysis C. Comparison Between Field Results and Analytical Results D. Final Conclusion

Test Road • Three Successive Sections • Same Dimensions – (150 m x 9.0 m ) • Different Pavement Structure 1. Granular Base Course (GBC) section 2. Cold Mix Asphalt (CMA) section 3. Hot Mix Asphalt (HMA) section • Instrumentation is Similar for the CMA & HMA Sections. Adjustment made for the GBC Section

Test Road Instrumentation PLAN VIEW Centre line Centre lane 390mm 390mm 1000mm 1000mm 1000mm 1000mm D.A.S Strain Transducer Temperature Profile Moisture Gauge Pressure Gauge CROSS-SECTION VIEW N.T.S. Hot Mix Asphalt 110 mm Cold Mix Asphalt 50 mm Granular Base Course 300 mm GBC – 50 mm GBC – 50 mm Subgrade Prep 150 mm 150 mm

Testing Sequence/1 Load Repetition number 1 2 3 4 5 Standard 18 kip @60km/hr � � � � � Standard 8 wheel Tandem(17000kg) @60 km/hr � � � � � Creep Standard 18 kip � Crane Creep � � � � � Standard 18 kip Crane 5 km/hr � � � � � Standard 18 kip Crane 10 km/hr � � � � �

Testing Sequence/2 Load Repetition number 1 2 3 4 5 Standard 18 kip Crane 10 km/hr � � � � � Standard 18 kip Crane 15 km/hr � � � � � Standard 18 kip Crane 20 km/hr � � � � � Standard 18 kip Crane 30 km/hr � � � � �

Testing Sequence/3 1 2 3 4 5 Standard 18 kip Crane 40 km/hr � � � � � Standard 18 kip Crane 50 km/hr � � � � � Standard 18 kip Crane 60 km/hr 4 axle configuration-CR01 � � � � � Standard 18 kip Crane 60 km/hr 7 axle configuration-CR02 � � � � � Standard 18 kip @60km/hr � � � � �

PRELIMINARY RESULTS � Preliminary results discuss the following: 1. Interfacial Strain (Between the Asphalt Concrete & the Granular Base Course Layers) a) Along travel direction (Longitudinal) b) Perpendicular to travel direction (Transversal) 2. Vertical Stress in the Sub-grade

Long. Interfacial Strain Longitudinal Strain-HMA section, Speed 60 km/hr 0.0012 0.001 0.0008 Strain mm/mm 0.0006 ST18 0.0004 CR01 CR02 0.0002 0 -0.0002 - 0.0004 0 0.2 0.4 0.6 0.8 1 1.2 1.4 Time (Seconds)

Max. Long. Interfacial Tensile Strains (ST18) (x 10 -6 ) Standard 18 Kips Truck Test Road Axle # for the Tested Vehicle Section Tested Vehicle 2 1 3 4 5 6 7 (x10 -6 ) (x10 -6 ) (x10 -6 ) (x10 -6 ) (x10 -6 ) (x10 -6 ) (x10 -6 ) Speiring 334 1053 1051 1031 1049 HMA - - - Crane – Four (379) (1362) (1345) (1361) (1392) Axles Configuration 1057 1703 1806 1677 1792 CMA - - - (CR01) (1704) (2238) (2382) (2110) (2309) Speiring 334 923 938 932 914 865 844 819 HMA Crane – (379) (1164) (1170) (1177) (1157) (1123) (1112) (1054) Seven Axles Configuration 1057 1732 1832 1844 1951 1783 1731 1766 (CR02) CMA (1704) (2261) (2273) (2343) (2347) (2278) (2122) (2226)

Long. Strain Comparison/1 (I) (II) (III) HMA & CMA CMA Section HMA Section Sections 10 - 20% 165% 170% 313% 267% CR01 CR01 CR02 ST18 CR01 CR02 ST18 CR02

Long. Strain Comparisons/2 HMA CMA (V) CMA (IV) Section Section Section HMA Section -65% +65% -85% Maximum Tensile Strain Under Wheel Path / Both Cranes for Both Cranes

Transversal Strain Results/1 • For both HMA & CMA Sections , Tensile Strains were Generated Under the Wheel Paths Travel Direction 1. For CR01 ε t ε t = (75-80)% ε l ε l 2. For CR02 ε t = (55-75)% ε l

Transversal Strain Results/2 • For CR01, Strain under OWP is 35-50% higher than under IWP Travel Direction • For CR02, Strain Under Center OWP is 15-30% higher Line OWP than Under IWP IWP

Trans. Strain Distribution I1 Travel Direction O1 I2 O2 I3 O3 O1 O2 O3 I1 I2 I1 I3 ST18 C T/C T C T/C T CR01 & CR02 T T C C C T

V. Stress in Sub-grade Vertical Pressure in the Sub-grade for Different Vehicles- HMA Section, V=60km/hr 25 Vertical Pressure (kPa) 20 15 ST18 CR01 10 CR02 5 0 0 0.5 1 1.5 2 Time (Seconds)

V. Stress on top of Subgrade (I) (II) HMA Section HMA Section 90-155% 35-110% 40-55% ST18 CR01 CR02 CR01 CR02

CONCLUSIONS & FUTURE WORK • No Clear or Final Conclusions Could be Presented Due to Limited Time Available for Full Analysis. June 27 – July 15 June 25-26, 2005 May 25 to June 24 18 days 2 days 2005 30 days Looking at all the Preparation for and Test road data and presenting Doing the Field Test Construction and preliminary results in Instrumentation this paper

Suggestions for Future Work • For Future Work. 1.Study the edge effect on the pavement response, making use of the strain gauges array design. 2.Include the tire characteristics to the variables in the testing program such as tire size, tire type, tire pressure …etc. 3.Investigate the effect of any future work to the test road by comparing current results with the new ones.