Asphalt Technology Course Performance Testing of HMA Performance Testing of HMA 1

Asphalt Technology Course Learning Objectives After this class, you will be able to … Describe goals of performance testing Describe factors considered for selecting tests Describe most critical test parameters Determine stress state in asphalt layer Describe three major distresses Conduct performance tests Analyze test results Performance Testing of HMA Performance Testing of HMA

General Information Performance Testing of HMA

Goals of Performance Testing Asphalt Technology/Chinese Delegation Asphalt Technology Course Goals of Performance Testing Identify mixtures prone to performance problems during the mix design process Identify potential performance problems during production (QC/QA) Predict performance during mix design Warranties Performance specifications Evaluate new materials or design tools to improve performance Performance Testing of HMA HMA Performance Testing Performance Testing of HMA 4

Why Distinguish Between Identify and Predict? Asphalt Technology/Chinese Delegation Asphalt Technology Course Why Distinguish Between Identify and Predict? Identify refers to a “go” or “no go” situation, e.g. “We think the mix will rut” or “We do not think the mix will rut” Predict refers to providing an idea of the magnitude of the distress, e.g. “We think the mix will rut 13 mm after 10 million ESALs” Performance Testing of HMA HMA Performance Testing Performance Testing of HMA 5

Asphalt Technology Course Asphalt Technology/Chinese Delegation Asphalt Technology Course Factors to Consider Reliability (identification, prediction) Time (sample preparation, testing) Variability of results Costs (equipment, operation) Others Calibration requirements Sophistication of data reduction Mobility of the equipment Applicability to test cores Performance Testing of HMA HMA Performance Testing Performance Testing of HMA 6

Most Critical Test Parameters Asphalt Technology/Chinese Delegation Asphalt Technology Course Most Critical Test Parameters Temperature Frequency (loading time) Load magnitude Mode of loading Specimen conditioning Specimen type (lab vs. field) Mixture variables: air voids Performance Testing of HMA HMA Performance Testing Performance Testing of HMA 7

Question List three critical test parameters Performance Testing of HMA

Major Distresses of Asphalt Pavements Performance Testing of HMA

Flexible Pavement Deflection Performance Testing of HMA

Asphalt Technology Course Asphalt Technology/Chinese Delegation Asphalt Technology Course Stresses Compression Tension Performance Testing of HMA HMA Performance Testing Performance Testing of HMA 11

Vertical Compressive Stresses Asphalt Technology/Chinese Delegation Asphalt Technology Course Vertical Compressive Stresses Performance Testing of HMA HMA Performance Testing Performance Testing of HMA 12

Horizontal Tensile Stresses Asphalt Technology/Chinese Delegation Asphalt Technology Course Horizontal Tensile Stresses Performance Testing of HMA HMA Performance Testing Performance Testing of HMA 13

Pavement Shear Stresses Asphalt Technology/Chinese Delegation Asphalt Technology Course Pavement Shear Stresses Performance Testing of HMA HMA Performance Testing Performance Testing of HMA 14

Three Major Distresses Rutting Rutting in HMA (compaction, mix design) Rutting in unbound base, subgrade (structure) Fatigue cracking Bottom-up cracking in thin pavements Top-down cracking in thick pavements Low temperature cracking Shrinkage of HMA due to low temperatures Performance Testing of HMA

Mix Rutting Performance Testing of HMA

Fatigue Cracking Surface Base Surface Base Surface UnboundBase Subgrade Performance Testing of HMA

Bottom-Up Fatigue Cracking Shear Stress at Crack Tip Neutral Axis HMA cracks Bending Tension Initiation Propagation Granular Base Subbase Fatigue cracking is significantly related to the pavement structure Performance Testing of HMA

Low Temperature Cracking Asphalt Technology/Chinese Delegation Asphalt Technology Course Low Temperature Cracking Performance Testing of HMA HMA Performance Testing Performance Testing of HMA 19

Asphalt Technology Course Asphalt Technology/Chinese Delegation Asphalt Technology Course Low Temperature Cracking Low temperature cracks on surface tensile stress tensile stress Low temperature crack growth in HMA Primarily affected by binder grade Performance Testing of HMA Performance Testing of HMA HMA Performance Testing 20

Questions What are the three major distresses in asphalt pavements? What may be the causes of these distresses? Performance Testing of HMA

Tests for Rutting Resistance Performance Testing of HMA

Tests for Rutting Resistance Wheel tracking tests Asphalt Pavement Analyzer (APA) Hamburg Wheel Tracking Device (HWTD) Static creep tests Creep test Flow time test Repeated load tests Flow number test Performance Testing of HMA

Asphalt Pavement Analyzer Performance Testing of HMA

APA Operating Characteristics Asphalt Technology/Chinese Delegation Asphalt Technology Course APA Operating Characteristics 100 to 120 psi hose pressure 100 to 120 lb load on the hose Usually run for 8000 cycles Temperature Originally 50 °C (120 °F) Currently recommend based on climatic PG grade Performance Testing of HMA HMA Performance Testing Performance Testing of HMA 25

Asphalt Technology Course Asphalt Technology/Chinese Delegation Asphalt Technology Course Example of APA Results HMA Performance Testing Performance Testing of HMA 26

Example “Go/No Go” Criteria Asphalt Technology/Chinese Delegation Asphalt Technology Course Example “Go/No Go” Criteria Agency Temp./Voids Criteria, mm AL 67C, 4% 4.5 high traffic GA 64C, 7% 5 high traffic 6 medium traffic 7 low traffic VA 50C, 7% 3.5 high traffic 5.5 medium traffic Performance Testing of HMA HMA Performance Testing Performance Testing of HMA 27

Which Mix Passes AL Criterion? Performance Testing of HMA

Hamburg Wheel Tracking Device (HWTD) Asphalt Technology/Chinese Delegation Asphalt Technology Course Hamburg Wheel Tracking Device (HWTD) Performance Testing of HMA HMA Performance Testing Performance Testing of HMA 29

Hamburg Test Parameters Asphalt Technology/Chinese Delegation Asphalt Technology Course Hamburg Test Parameters Test combines rutting performance with moisture susceptibility Load = 685 N (154 lb) Full test is 20,000 passes Temperature - 50 to 60 C VTM - 6 + 0.5 % Tested under water Performance Testing of HMA HMA Performance Testing Performance Testing of HMA 30

Example of HWTD Results Performance Testing of HMA

Asphalt Technology Course Asphalt Technology/Chinese Delegation Asphalt Technology Course HWTD Criteria CO: 10 mm @ 20,000 passes TX: (0.5 in failure rut) 10,000 passes for PG 64-XX 15,000 passes for PG 70-XX 20,000 passes for PG 76-XX Performance Testing of HMA HMA Performance Testing Performance Testing of HMA 32

Which Mix Passes CO Criterion? Performance Testing of HMA

Asphalt Technology Course Asphalt Technology/Chinese Delegation Asphalt Technology Course Creep Test Results do not correlate well with pavement rutting Performance Testing of HMA HMA Performance Testing Performance Testing of HMA 34

Flow Time (Ft)Test D(t) = ε(t)/σd Performance Testing of HMA

Flow Time Test (cont.) - Primary: strain rate decreases with loading time - Secondary: strain rate is constant with loading time - Tertiary: strain rate increases with loading time - Lower flow time should correspond to greater rutting in the field Performance Testing of HMA HMA Performance Testing 36

Flow Number (FN) Test 7% voids Deviator stress = 70 – 100 psi Confining pressure = 0 - 10 psi Performance Testing of HMA

Flow Number Test (cont.) - Primary: strain rate decreases with loading time - Secondary: strain rate is constant with loading time - Tertiary: strain rate increases with loading time - Lower flow number should correspond to greater rutting Performance Testing of HMA

Example of Proposed FN Criteria (based on Fn vs. rate of rutting) Traffic, ESALs Rut Threshold 9.5 mm 12.5 mm 1 million 105 89 3 million 202 171 5 million 274 232 7 million 335 284 10 million 414 351 Test temp: 58C, Confining pressure = 70 psi, Deviator stress = 10 psi; Plant produced mixes

Tests for Fatigue Cracking Resistance Performance Testing of HMA

Tests for Fatigue Cracking Bottom-up fatigue cracking Bending Beam Fatigue Test (BBFT) Push-Pull Test Top-down fatigue cracking Energy Ratio (MR, IDT) Performance Testing of HMA

BBFT Performance Testing of HMA

Beam Preparation Performance Testing of HMA

Asphalt Technology Course Asphalt Technology/Chinese Delegation Asphalt Technology Course Beam Fatigue Testing Beam size – 2.5” by 2” by 15” Usually run @ 7% VTM 0.1 sec load and 0.4 sec unload Fatigue tests are usually plotted as log strain vs Log N (number of cycles) Performance Testing of HMA HMA Performance Testing Performance Testing of HMA 44

Asphalt Technology Course Asphalt Technology/Chinese Delegation Asphalt Technology Course Fatigue Testing Controlled stress Applicable for thick AC pavements Controlled strain For pavements less than 2 inches 50% loss in initial beam stiffness Previous research indicates shift factors of 10 to 80 for number of cycles to failure in field versus lab (more cycles in field) Performance Testing of HMA HMA Performance Testing Performance Testing of HMA 45

Example Fatigue Test Result Asphalt Technology/Chinese Delegation Asphalt Technology Course Example Fatigue Test Result Performance Testing of HMA HMA Performance Testing Performance Testing of HMA 46

Beam Fatigue Testing – Failure Propagation Asphalt Technology/Chinese Delegation Asphalt Technology Course Beam Fatigue Testing – Failure Propagation Performance Testing of HMA HMA Performance Testing Performance Testing of HMA 47

Asphalt Technology Course Asphalt Technology/Chinese Delegation Asphalt Technology Course Fatigue Curve Performance Testing of HMA HMA Performance Testing Performance Testing of HMA 48

Which Mix Would Last Longer? Performance Testing of HMA

Tests for Low Temperature Cracking Resistance Performance Testing of HMA

Tests for Low Temperature Cracking Temperature Stress Restrained Specimen Test (TSRST) Indirect Tensile Test (IDT) Semi-Circular Bending Test (SCB) Disc-shaped Compact Tension Test (DCT) Texas Overlay Tester (OT) Performance Testing of HMA

Temperature Stress Restrained Specimen Test (TSRST) Asphalt Technology/Chinese Delegation Asphalt Technology Course Temperature Stress Restrained Specimen Test (TSRST) Performance Testing of HMA HMA Performance Testing Performance Testing of HMA 52

Asphalt Technology Course Asphalt Technology/Chinese Delegation Asphalt Technology Course TTI Overlay Tester Performance Testing of HMA HMA Performance Testing Performance Testing of HMA 53

Asphalt Technology Course Asphalt Technology/Chinese Delegation Asphalt Technology Course TTI Overlay Tester Performance Testing of HMA HMA Performance Testing Performance Testing of HMA 54

Tests for Mechanistic Properties for Pavement Design Performance Testing of HMA

M-E Pavement Design Climate Materials Traffic Structure Response Level 1: I know a lot about this input… Level 2: I know some about this input… Level 3: I know very little about this input… Traffic Materials Structure Time Damage Damage Accumulation Distress Response

Dynamic Modulus (|E*|) Performance Testing of HMA

Asphalt Technology Course Asphalt Technology/Chinese Delegation Asphalt Technology Course Specimen for E* Test 150 mm by 100 mm, cored from SGC specimen Performance Testing of HMA HMA Performance Testing Performance Testing of HMA 58

E* Test Parameters Specimen Va = 7±0.5% AASHTO TP 62 – Full procedure Test temperatures: -10, 4.4, 21.1, 37.8, 54.4oC Frequency: 25, 10, 5, 1, 0.5, 0.1 Hz AASHTO TP 79 – Reduced procedure Test temperatures: 4.4, 21.1, (35 - 45)oC Frequency: 10, 1, 0.1, (0.01) Hz Use Hirsch model to predict max E* Performance Testing of HMA

Asphalt Technology Course Asphalt Technology/Chinese Delegation E* Test Results osin(t) / o o o , osin(t-) Time, t Performance Testing of HMA Performance Testing of HMA HMA Performance Testing 60

Master Curve Development Asphalt Technology Course Master Curve Development 70F Performance Testing of HMA Performance Testing of HMA 61

Asphalt Technology Course Shift Factor 58 86 Shift factors vary with HMA mixtures Performance Testing of HMA Performance Testing of HMA 62

Time-Temperature Superposition Asphalt Technology Course Time-Temperature Superposition 70F 58F 86F Performance Testing of HMA Performance Testing of HMA 63

Question What is the input for asphalt material in ME design? What is the curve used to present E*? Performance Testing of HMA

Asphalt Technology Course Asphalt Technology/Chinese Delegation Asphalt Technology Course Summary Rutting Tests No test has demonstrated ability to identify/predict rutting over wide range of mixes and climates Several agencies have developed local criteria to identify rut susceptible mixes with torture testers Repeated load test appears promising Performance Testing of HMA HMA Performance Testing Performance Testing of HMA 65

Asphalt Technology Course Asphalt Technology/Chinese Delegation Asphalt Technology Course Summary Fatigue Tests Good for ranking mixes Difficult to relate to field Low Temperature Cracking Tests Several tests are being evaluated Binder testing may be used for most applications Test for ME pavement design Dynamic modulus Performance Testing of HMA HMA Performance Testing Performance Testing of HMA 66