Temperature Behaviour of Asphalt Abiy Bekele PhD student at - - PowerPoint PPT Presentation

Automated Non-contact Resonance Testing for Low Temperature Behaviour of Asphalt

Abiy Bekele PhD student at Building materials division Supervisor: Nils Ryden Co-Supervisors: Anders Gudmarsson, Björn Birgisson and Denis Jelagin Sponsors: Transport Administration of Sweden and BVFF

Resonance Testing on Asphalt

q Stress waves can be imposed into a material through impacting q Different modes of vibration depending on the application of the excitation q Time domain sinosoidal signals converted to frequency domain q RAS used for determining elastic and visco-elastic properties

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1 2 3 4 5 6 x 10

• 3
• 1000
• 500

500 1000 Time [s] Acceleration [m/s× ] 0.5 1 1.5 2 x 10

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100 200 300 Frequency [Hz] Acceleration [m/s× ]

Research Questions

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q Impacting for Resonance testing is carried out manually Automating the testing procedure q Asphalt is highly susceptible to temperature An improved control of measurement temperatures required q The long term sole effects of low temperature conditioning on asphalt is yet to be fully understood q Cyclic low temperature effects on asphalt

Non-Contact Acoustic excitation

q Resonance induced by means of air- coupled acoustics q Irradiating sound waves within acoustic frequency range q Useful in modal experiments that require small measureable strains

Adopted from Kageyoshi Katakura1, Ryo Akamatsu2, Tsuneyoshi Sugimoto2 and Noriyuki Utagawa

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Experimental Protocol: Non-Contact method

Specimen Foam for boundry conditions Response after excitation Accelero meter

0.8 0.85 0.9 0.95 1 1.05 1.1 1.15 1.2 x 10

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2 4 6 8 10 12

Acceleration [m/s2] Frequency [Hz]

2 4 6 8 10

• 0.015
• 0.01
• 0.005

0.005 0.01 0.015

Volts Time [Sec]

Loud Speaker Signal Processing

q Automated Non-contact method of resonance application

Mode of vibration

Data Aquisition

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Measuremement at Low temperatures

q Measurement on sample ABT-11 q RF increases with temperature decrease q Amplitude increases as temperature decreases

0.8 0.85 0.9 0.95 1 1.05 1.1 1.15 1.2 x 10

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5 10 15 20 25 Acceleration [m/s

2]

Frequency [Hz] At 0 At -10°C At -20°C At -30°C At -40°C

• 50
• 40
• 30
• 20
• 10

10 20 40 60 80 100 120 140 160 180 200

T emperature ¡( ¡

° ¡C )

Quality ¡F actor

Quality factor RF damped

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Example of Results

q General increase of dynamic modulus with decrease in temperature q Behaviour of visco-elasticity can be monitored q Possibility to compare different mixtures

• 50 -45
• 40
• 35
• 30 -25
• 20
• 15
• 10
• 5

5 10 0.96 0.98 1 1.02 1.04 1.06 1.08 x 10

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Temperature (

° C)

Resonance Frequency(Hz)

ABT 11 ABS 11

• 50 -45
• 40
• 35
• 30 -25
• 20
• 15
• 10
• 5

5 10 2.6 2.8 3 3.2 3.4 3.6 3.8 x 10

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Temperature (

° C)

Dynamic Modulus(Pa)

ABT 11 ABS 11

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Remarks

q The proposed method showed good repeatability and reproducibility q An automated technique q Good aggreement with contact Resonance measurement q Non-contact method of measurement has the following advantages § Avoids variation of measurement results § Temperature can be kept constant during measurement § Efficient in studying low temperature behaviours of asphalt § Measurement procedure is relatively simpler

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Thank You!

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