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Characterizing the low strain complex modulus of asphalt concrete specimens through optimization of frequency response functions
KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.
KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.
KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.ORCID-id: 0000-0003-0889-6078
2012 (Engelska)Ingår i: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 132, nr 4, s. 2304-2312Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Measured and finite element simulated frequency response functions are used to characterize the low strain (similar to 10(-7)) complex moduli of an asphalt concrete specimen. The frequency response functions of the specimen are measured at different temperatures by using an instrumented hammer to apply a load and an accelerometer to measure the dynamic response. Theoretical frequency response functions are determined by modeling the specimen as a three-dimensional (3D) linear isotropic viscoelastic material in a finite element program. The complex moduli are characterized by optimizing the theoretical frequency response functions against the measured ones. The method is shown to provide a good fit between the frequency response functions, giving an estimation of the complex modulus between minimum 500 Hz and maximum 18 vertical bar 000 Hz depending on the temperature. Furthermore, the optimization method is shown to give a good estimation of the complex modulus master curve.

Ort, förlag, år, upplaga, sidor
Acoustical Society of America (ASA), 2012. Vol. 132, nr 4, s. 2304-2312
Nyckelord [en]
Asphalt concrete, Dynamic response, Optimization, Three dimensional
Nationell ämneskategori
Infrastrukturteknik
Identifikatorer
URN: urn:nbn:se:kth:diva-104235DOI: 10.1121/1.4747016ISI: 000309650600036Scopus ID: 2-s2.0-84867340539OAI: oai:DiVA.org:kth-104235DiVA, id: diva2:563591
Anmärkning

QC 20121112

Tillgänglig från: 2012-10-30 Skapad: 2012-10-30 Senast uppdaterad: 2017-12-07Bibliografiskt granskad
Ingår i avhandling
1. Laboratory Seismic Testing of Asphalt Concrete
Öppna denna publikation i ny flik eller fönster >>Laboratory Seismic Testing of Asphalt Concrete
2012 (Engelska)Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Nondestructive laboratory seismic testing to characterize the complex modulus and Poisson’s ratio of asphalt concrete is presented in this thesis. These material properties are directly related to pavement quality and the dynamic Young’s modulus is used in thickness design of pavements. Existing standard laboratory methods to measure the complex modulus are expensive, time consuming, not truly nondestructive and cannot be directly linked to nondestructive field measurements. This link is important to enable future quality control and quality assurance of pavements based on the dynamic modulus.Therefore, there is a need for a more detailed and accurate laboratory test method that is faster, more economic and can increase the understanding and knowledge of the behavior of asphalt concrete. Furthermore, it should be able to be linked to nondestructive field measurements for improved quality control and quality assurance of pavements. Seismic testing can be performed by using ultrasonic measurements, where the speed of sound propagating through a material with known dimensions is measured. Seismic testing can also be used to measure the resonance frequencies of an object. Due to any excitation, a solid resonates when the frequency of the applied force matches the natural frequencies of the object. In this thesis, resonance frequency measurements have been performed at several different temperatures by applying a load impulse to a specimen while measuring its dynamic response. The measured resonance frequencies and the measured frequency response functions have been used to evaluate the complex modulus and Poisson’s ratio of asphalt concrete specimens. Master curves describing the complex modulus as a function of temperature and loading frequency have been determined through these measurements.The proposed seismic method includes measurements that are significantly faster, easier to perform, less expensive and more repeatable than the conventional test methods. However, the material properties are characterized at a higher frequency range compared to the standard laboratory methods, and for lower strain levels (~10-7) compared to the strain levels caused by the traffic in the pavement materials. Importantly, the laboratory seismic test method can be linked together with nondestructive field measurements of pavements due to that the material is subjected to approximately the same loading frequency and strain level in both the field and laboratory measurements. This allows for a future nondestructive quality control and quality assurance of new and old pavement constructions.

Ort, förlag, år, upplaga, sidor
Stockholm: KTH Royal Institute of Technology, 2012. s. vii, 23
Serie
Trita-TSC-LIC, ISSN 1653-445X ; 12:009
Nationell ämneskategori
Infrastrukturteknik
Identifikatorer
urn:nbn:se:kth:diva-104236 (URN)978-91-85539-97-0 (ISBN)
Presentation
2012-12-19, B26, Brinellvägen 23, KTH, Stockholm, 09:00 (Engelska)
Opponent
Handledare
Anmärkning

QC 20121120

Tillgänglig från: 2012-11-20 Skapad: 2012-10-30 Senast uppdaterad: 2012-11-20Bibliografiskt granskad
2. Resonance Testing of Asphalt Concrete
Öppna denna publikation i ny flik eller fönster >>Resonance Testing of Asphalt Concrete
2014 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

This thesis present novel non-destructive laboratory test methods to characterize asphalt concrete. The testing is based on frequency response measurements of specimens where resonance frequencies play a key role to derive material properties such as the complex modulus and complex Poisson’s ratio. These material properties are directly related to pavement quality and used in thickness design of pavements.

Since conventional cyclic loading is expensive, time consuming and complicated to perform, there has been a growing interest to apply resonance and ultrasonic testing to estimate the material properties of asphalt concrete. Most of these applications have been based on analytical approximations which are limited to characterizing the complex modulus at one frequency per temperature. This is a significant limitation due to the strong frequency dependency of asphalt concrete. In this thesis, numerical methods are applied to develop a methodology based on modal testing of laboratory samples to characterize material properties over a wide frequency and temperature range (i.e. a master curve).

The resonance frequency measurements are performed by exciting the specimens using an impact hammer and through a non-contact approach using a speaker. An accelerometer is used to measure the resulting vibration of the specimen. The material properties can be derived from these measurements since resonance frequencies of a solid are a function of the stiffness, mass, dimensions and boundary conditions.

The methodology based on modal testing to characterize the material properties has been developed through the work presented in paper I and II, compared to conventional cyclic loading in paper III and IV and used to observe deviations from isotropic linear viscoelastic behavior in paper V. In paper VI, detailed measurements of resonance frequencies have been performed to study the possibility to detect damage and potential healing of asphalt concrete. 

The resonance testing are performed at low strain levels (~10^-7) which gives a direct link to surface wave testing of pavements in the field. This enables non-destructive quality control of pavements, since the field measurements are performed at approximately the same frequency range and strain level.

Ort, förlag, år, upplaga, sidor
Stockholm: KTH Royal Institute of Technology, 2014. s. xiii, 51
Serie
TRITA-TSC-PHD ; 14:008
Nyckelord
Resonance frequencies; Modal testing; Frequency response functions; Cyclic loading; Tension-compression tests; Complex modulus; Complex Poisson’s ratio
Nationell ämneskategori
Infrastrukturteknik
Identifikatorer
urn:nbn:se:kth:diva-155906 (URN)978-91-87353-50-5 (ISBN)
Disputation
2014-12-08, Kollegiesalen, Brinellvägen 8, KTH, Stockholm, 09:00 (Engelska)
Opponent
Handledare
Anmärkning

QC 20141117

Tillgänglig från: 2014-11-17 Skapad: 2014-11-14 Senast uppdaterad: 2015-06-02Bibliografiskt granskad

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Birgisson, Björn

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