nondestructive in -place strength profiling of concrete ...docs.trb.org/prp/07-1406.pdf ·...

Nondestructive In-Place Strength Profiling of Concrete Pavementsby Resonance Search Technique

Paper No. 07-1406

Mi-Ra Cho, Ph.D.Adjunct Professor

Department of Civil EngineeringChung-Ang University

Nae-Ri, DaeDeok-Myeon, AnSeong-SiGyeongGi-Do, 456-756, Republic of Korea

Telephone: +82-31-670-4661 Fax: +82-31-675-1387E-mail: [email protected]

Sung-Ho Joh, Ph.D.Associate Professor

Department of Civil EngineeringChung-Ang University

Nae-Ri, DaeDeok-Myeon, AnSeong-SiGyeongGi-Do, 456-756, Republic of Korea


Soo Ahn Kwon, Ph.D.Research Fellow

Korea Institute of Construction Technology2311, Daehwa-Dong, Ilsan-Gu, Goyang-SiGyeongGi-Do, 411-712 Republic of Korea


Tae-Ho Kang, Ph.D.Post-Doctoral Fellow

Department of Civil EngineeringUtah State University4110 Old Main Hill

Logan, UT 84322-4110Telephone: 435-797-2932 Fax: 435-797-1185

E-mail: [email protected]

Total number of words = 6785 (text = 4785, 8 figures =2000)

A Paper Preparedfor the

86th Annual Meeting of theTransportation Research Board

Washington, D.C.

January 2007

TRB 2007 Annual Meeting CD-ROM Original paper submittal - not revised by author.

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ABSTRACT

Compressive strength of concrete is one of the important parameters in quality assurance of a new concrete pavement and also in the evaluation of existing concrete pavements. A reliable in-place test technique for the assessment of concrete strength is required for both quality assurance of new concrete pavements and structural-integrity assessment of existing pavements. In this paper, a reliable and practical procedure is proposed to evaluate strength variation of concrete pavements with depth. The proposed procedure first evaluates shear-wave velocity profile of a pavement by a new seismic method called the resonance search (RS) technique and then converts the shear-wave velocity profile to strength profile, using the relationship between shear-wave velocity and compressive strength. The proposed procedure has two significances in methodology: the use of shear waves and the refined determination of pavement thickness. Unlike compression waves, shear waves are not influenced by mode conversion, confinement effects and dimension ratio effects which induce the change of propagation velocity. Also the proposed procedure is powered with the RS technique to determine pavement thickness. The RStechnique, based on forward modeling of wave propagation, improves accuracy in thickness evaluation significantly. Field applications were made at airport apron and two express highways to prove reliability and feasibility of the proposed procedure. In the field applications, the relationships between shear-wave velocity and compressive strength were established from drilled cores. Using the site-specific relationship, compressive strengths of other sections could be estimated from shear-wave velocities evaluated by the RS technique.

INTRODUCTION

The current practice to assess compressive strength of concrete pavement is to test field-cured cylinders or drilled cores from concrete pavement by unconfined compression tests. Cores drilled from pavement may be a good representative of in-place concrete, but coring is usually limited because coring operation is an expensive, labor-intensive and time-consuming job. Also, field-cured cylinders may not represent in-place quality of concrete strength due to variability in environmental conditions and construction activities. Therefore, as a practical alternative of core-or cylinder-based measurements, nondestructive techniques have been adopted for the assessment of compressive strength. The nondestructive tests to estimate concrete strength include maturity method, rebound test, and stress-wave propagation (or seismic) methods. Among the available nondestructive techniques, seismic propagation methods are more applicable than any other methods in that seismic methods can assess thickness as well as strength of the pavement. Strength is estimated from modulus determined by the seismic methods. Therefore, the methods require the modulus-strength relationship developed in advance in the laboratory or modeled from the drilled cores of pavements by resonance tests and compression tests.

The currently available seismic methods include impulse response method, impact-echo method and surface-wave method. In the 1980’s, the surface wave technique based on Rayleigh waves was investigated as a method to evaluate modulus and thickness of the concrete pavement. From the late 1980’s to the 1990’s, the impact-echo method was introduced for the nondestructive evaluation methodology as itself or as a combined method with the surface wave method. The surface wave method and the impact-echo method are convenient and practical approaches, but inherently the methods have complexities such as mode conversion in wave propagation, limited accuracy and reliability due to the simplification in the analysis procedure.


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The simplifications, which lead to low reliability in the resulting strength of concrete pavement,include the evaluation of Young’s modulus from average surface-wave velocity and the assumption of 2-D plane-wave condition and Poisson’s ratio.

In this paper, a new procedure is proposed to evaluate strength of concrete pavement. To overcome the limitations of the previous approaches, shear waves were incorporated in strength evaluation rather than compression waves. Also to investigate strength variation with depth in pavements, a new seismic technique called the RS technique, which combines surface-wave method and resonance method, was proposed. The validity of the RS technique was verified by numerical modeling of stress-wave propagation in a concrete pavement. Also, field applicationswas made at concrete apron of Gimpo International Airport, concrete pavements of Seohaeanand YoungDong express highways to verify feasibility and reliability of the proposed procedure.

NONDESTRUCTIVE EVALUATION OF CONCRETE STRENGTH

Stress-Wave Techniques for the Evaluation of Concrete Strength

In the literature, typical stress-wave techniques used for nondestructive evaluation of concrete pavements include the Spectral-Analysis-of-Surface-Waves (SASW) method and the resonance method. A brief discussion on these methods is provided in the following.

SASW Method

The SASW method is a non-intrusive method to evaluate the stiffness profile of natural geotechnical sites, pavement systems and concrete structures by measuring the propagation velocity of surface waves (1). The measurement is to record particle velocities or acceleration induced by the propagating surface waves at two locations. The measured velocity or acceleration time histories are transformed to the frequency domain to determine phase differences between two receivers for a series of frequencies. The phase differences are then used to determine the propagation velocities of surface waves at a series of frequencies, which form a phase-velocity dispersion curve. The inversion analysis is then used to determine the shear-wave velocity profile from the dispersion curve.

Since the SASW method was originally developed for elastic modulus of pavement systems (2,3), many researchers have studied feasibility of the SASW measurements as an alternative means for quality control and quality assurance of pavement systems. The researches included thickness of pavement layers (3-7), stiffness profile of pavement systems (3-5) and factors affecting the SASW testing at pavement systems (7). In the application of SASW method, concrete pavement systems are more complicated than native geotechnical sites in that a concrete pavement is much stiffer than underlying layers and pavement thickness is relatively thin. To overcome the complexity in SASW measurements, some researches were performed to find out the best measurement configuration (7,8). On the other hand, Roësset et al. (8-10) employed the dynamic stiffness matrix method to model surface wave propagation in pavement systems, which provided a stable theoretical background to investigate the nondestructive evaluation of concrete pavement parameters.

Even with the extensive research on the SASW method for pavement applications, the SASW method has inherent problems in testing pavements. The multiple reflections induced from top and bottom boundaries of pavements contaminate surface waves so that the phase velocities corresponding to wavelengths larger than pavement thickness are not reliable.


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Therefore, the material of the lower pavement section can not be sampled reliably and the pavement thickness can not be reliably evaluated, neither.

Resonance Method

Stress waves from an impulse source applied to the top surface of a plate-like structure are reflected back at the bottom of the structure or at internal anomalies within the structure. Multiple reflections between two boundaries are analyzed to retrieve thickness of the structure or depth to internal anomalies or defects. The seismic method based on the multiple reflections in the bounded media is called the resonance method.

One of the typical resonance methods is the impact-echo method. The method was originally developed by Sansalone and Carino (11), and later the method was improved with modification of the theory (12). The modified theory of impact-echo method introduced shape factor to accommodate for discrepancy among the true P-wave velocity measured directly from a through-transmission, pulse-echo measurement and the apparent P-wave velocity measured indirectly through impact-echo tests on plates of known thickness. Also, Cho (13) proposed a new procedure using SH waves rather than P waves in impact-echo testing to overcome theinherent mode-conversion problems of P waves, and also suggested to use multiple receivers to incorporate the effects of varying resonant frequencies with receiver location in the analysis.

The impact-echo method has been applied to nondestructive evaluation of concrete pavements by many researchers including Sansalone (14) and Nazarian (15,16). Sansalone developed a procedure to determine thickness of concrete highway pavements using the impact-echo method, and Nazarian used the impact-echo method to evaluate pavement thickness with velocities determined by the surface-wave method. Albeit many successful applications of the impact-echo method in pavements, the impact-echo method still requires a reliable evaluation of the average P-wave velocity for pavement material. Also, a sophisticated analytical procedure should be provided to handle mode conversion occurring in pavements with vertical variability.

Relationship between Stress-Wave Velocity and Concrete Strength

Parker (17) was one of the researchers who developed the relationship between pulse velocity and compressive strength, and he found pulse velocity is relatively insensitive to strength for hardened concrete. Malhotra and et al. (18) reported also that the wave velocity method is inaccurate in predicting the in-place compressive strength even under the laboratory condition. However, Sturrup and et al. (19) realized that the relationship between pulse velocity and concrete strength is dependent upon many factors such as coarse aggregates, curing condition, aging and moisture content. Finally with the consideration of the influencing factors in establishing the velocity-strength relationship, the reliable relationships were proposed. Pessiki and Johnson (20) made one of the successful researches in estimating the early-stage concrete strength in plate structures by the impact-echo method.

In all the correlations between wave velocity and concrete strength, compression waves have been used in pulse-wave or ultrasonic-wave measurements. In this paper, shear-wave velocity was used for the correlations instead of compression waves. Unlike compression waves, shear waves are not subject to mode conversion in wave propagation, nor influenced by moisture in concrete. Also even the constraint conditions do not affect shear-wave velocities. Therefore, the measured shear-wave velocities are more consistent than compression-wave velocities. Figures 1(a) and 1(b) show measurement configurations for shear-wave and unconfined


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compression-wave measurements, respectively, by the optimized shear-wave resonance (OSR)tests (21). Typical frequency responses for shear-wave and compression-wave measurements are shown in Figure 1(c). A series of OSR tests and unconfined compression tests were performed for concrete mixes with different contents of fly ashes, different water-cement ratios and different aging. The correlations between wave velocities and strengths are shown in Figure 1(d). The resulting correlation between shear-wave velocity and strength turned out to be similar to the correlation for unconfined compression waves in the aspect of the geometric increase of strength for increasing velocity.

PROPOSED ALGORITHM FOR THE IN-PLACE STRENGTH PROFILING OF CONCRETE PAVEMENTS

A new algorithm based on the stress-wave measurements was proposed to characterize strength variation of concrete pavements with depth. As depicted in Figure 2, the proposed procedure first establishes the relationship between shear-wave velocity and compressive strength of concrete from field-cured cylinders or drilled cores, and then measures the shear-wave velocity profile of concrete pavement by the RS technique. The measured shear-wave velocity profile is then converted to strength profile, using the predefined relationship of shear-wave velocity and strength. Unlike the previous methods, the proposed procedure does not assume Poisson’s ratio in evaluating concrete strength and does not incorporate simplification in analysis steps, neither. Therefore, more reliable evaluation of concrete strength profiling was enabled.

The relationship between shear-wave velocity and compressive strength in the first phase can be obtained using the OSR tests and unconfined compression tests. The second phase, the shear-wave velocity profiling of concrete pavements, is performed by the RS technique. The RS technique combines the advantages of the surface-wave method and the resonance method, and evaluates the vertical variation of shear-wave velocity in concrete pavements. The details of the RS technique are discussed in the following section.

RESONANCE SEARCH TECHNIQUE FOR THE EVALUATION OF SHEAR-WAVE VELOCITY PROFILE AND THICKNESS OF CONCRETE PAVEMENTS

The RS technique, which combines the advantages of the SASW method and the resonance method and also minimizes the shortcomings of both methods, was proposed in this paper. The SASW method is good at measuring shear-wave velocity of material, and the resonance method is reliable in determining the frequency for multiple reflections of body waves. The algorithm of the RS technique is provided in Figure 3. As illustrated in Figure 3, the RS technique consists of two phases: determination of shear-wave velocity profile and resonance search for thickness determination. Each phase is discussed in details in the following.

Determination of Shear-Wave Velocity Profile

In the first phase of the RS technique, the shear-wave velocity profile of a concrete slab is determined. First of all, the resonant frequency of body waves is determined from the acceleration spectrum or transfer function measured in performing SASW tests, and the phase difference between two receivers at the resonant frequency is determined. Then, the wavelength for the resonant frequency is calculated using the inter-receiver distance and phase difference. Next, the inversion analysis is performed to determine shear-wave velocity profile of the


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concrete slab. The shear-wave velocity profile is assumed to have two to three layers, dependent upon situations. In case of three layers, the top layer is a deteriorated concrete layer, the middle layer is a sound concrete layer and the bottom layer is a soft subgrade layer which works as a reflecting boundary for body waves. Shear-wave velocity and thickness of the subgrade layer is fixed and not perturbed in the inversion analysis. In the inversion analysis, the thickness of the concrete slab is initially set to the wavelength for the resonant frequency. The joint inversion analysis, which perturbs shear-wave velocity and thickness of the concrete slab, is employed. The array inversion algorithm (22) needs to be performed to improve the accuracy of a resulting shear-wave velocity profile.

Determination of Pavement Thickness

The next phase is to determine thickness of a concrete pavement. In the inversion analysis, the determination of the middle-layer thickness is not reliable due to multiple reflections of body waves. Therefore, in the second phase of the RS technique, a search technique is involved to find thickness of the middle layer. The basis of the search technique is to find the thickness of the middle layer which gives the resonant frequency identical to the measured resonant frequency. The relationship between resonant-frequency and plate thickness is defined by the forward modeling analysis based on the dynamic stiffness matrix method (10). The relationship is usually fit to a linear trend in the logarithmic scale. In the relationship, at least four or five resonant frequencies need to be included for different pavement thicknesses. The recommended pavementthicknesses are -20, -10, 0, 10, 20 % of the middle-layer thickness determined by the SASW inversion analysis. Finally, the pavement thickness is determined as the one corresponding to the measured resonant frequency from the resonant frequency-plate thickness relationship.

Numerical simulations of the resonance search technique

To verify validity of the proposed RS technique, the numerical simulation of the RS techniquewas performed using the dynamic stiffness matrix method, which enables the 3-D modeling of wave propagation. The model of a pavement used for the numerical simulation is a three-layer system which includes 0.05-m deteriorated soft concrete layer, 0.25-m sound stiff concrete layer and soft subgrade layer. The shear-wave velocities are set to 1500, 2400, 50 m/sec for the top, middle concrete layers and the subgrade layer, respectively. The displacement spectrum at the first receiver shows resonance at 6,012 Hz, and the corresponding unwrapped angle is 390.3 deg, as shown in Figures 4(a) and 4(b). And the wavelength for the resonant frequency is calculated to be 0.277 mm, as illustrated in Figure 4(b). With the phase-velocity dispersion curve in Figure4(c), the joint inversion analysis was performed for the 0.277-m thick slab. The resulting shear-wave velocity profile is shown in Figure 4(d). The forward modeling analyses are performed for different layer thicknesses and the corresponding resonant frequencies are determined, as shown in Figure 4(e). For the forward modeling analysis, the layer parameters were assigned to the ones determined by the SASW inversion analysis. Only the thickness of the middle layer was changed. And, the linear trend was established in the logarithmic scale, as shown in Figure 4(f). Finally, the pavement thickness can be determined to be 0.299 m for the resonant frequency from the displacement spectrum of Figure 4(a). The resulting shear-wave velocities are 1,504 and 2,403 m/sec for top and middle layers, which are almost the same as exact values of 1,500 and 2,400 m/sec. Also, the first layer thickness and the total pavement thickness resulted in 0.051 m and 0.299 m, which are also very close to the exact values of 0.05 m and 0.3 m.


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FIELD APPLICATIONS

For the verification of feasibility and reliability of the proposed procedure, three field applications were made. Pavement of airport apron and two concrete highway pavements were selected for the field applications. The tested apron is located at an isolated area and has not been subject to significant loading. The tested highway pavements used to be part of a tollgate area. The pavement sections are now closed and not used for traffic.

Tests for the RS Technique

The measurement hardware and configuration is displayed in Figure 5(a). Three receivers are employed for RS tests. The RS tests consist of SASW tests for the phase-spectrum measurement and resonance tests for the amplitude-spectrum measurement. In case of phase-spectrum measurement, 0.1- and 0.3-m receiver spacings were incorporated to measure phase velocities for the top-to-bottom material altogether. In the amplitude-spectrum measurements, an instrumented hammer, PCB 086C01, with a piezo-ceramic accelerometer embedded inside was employed to measure a transfer function between accelerometer and source. The transfer function is equivalent to a normalized response for the given source function so that transferfunction is more beneficial in identifying resonance than just power spectrum. Employedaccelerometers were miniature types of piezo-ceramic accelerometers, PCB 352C68.

A typical amplitude spectrum measured by the resonance test is shown in Figure 5(b). A clear resonance is observed at 5,376 Hz. The phase spectrum measured using 0.3-m receiver spacing at the same site is also shown in Figure 5(c). At the resonant frequency, the phase spectrum shows a distorted trend, which implies an unusual event like multiple reflections. Using the approximate wavelength of the resonant frequency and the phase spectrum of the transfer function, a preliminary shear-wave velocity profile was evaluated as a dotted line in Figure 6(a). A subsequent resonance search reveals that the thickness of concrete pavement is 0.349 m, as a solid line shown in Figure 6(b). Based on the relationship between shear-wave velocity and compressive strength (Figure 6(c)), the shear-wave velocity profile was converted to strength profile (Figure 6(d)). The velocity-strength relationship in Figure 6(c) was developed using several drilled cores from the site, and discussed later in this section in more details.

Determination of Pavement Thickness

A total of 26 locations were tested by the proposed RS technique, and 36 cores weredrilled at the test locations. At some test locations, three cores were drilled for multiple unconfined compression tests. In case of airport pavements, the pavements were too thick to drill through, so that the cores were broken in the middle. Therefore, pavement thicknesses and shear-wave velocity profiles were evaluated for 21 test locations, and compressive strength was evaluated for eight test locations. Figure 7 compares thicknesses and shear-wave velocities of concrete pavements determined by the RS tests and the direct measurements for drilled cores.

In case of pavement thickness, the thicknesses measured by the RS tests are well compared with the core lengths measured directly from drilled cores. The average error in evaluation of thickness is 3.3 %. The minimum and maximum errors are 0.16 % and 7.9 %, respectively. For comparisons, the analysis procedure of the impact-echo method was applied to the same set of measured data, and thicknesses were evaluated, as displayed in Figure 7(a). P-wave velocities, which are required in the analysis procedure of the impact-echo method, wereestimated from shear-wave velocities determined by the SASW tests. When Poisson’s ratio was assumed to be 0.17, the average error of thickness was 5.2 %, and the error ranged from 0.32 %


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to 23 %. With Poisson’s ratio of 0.23, the average error rose to 7.0 %, and the error ranged from 1.9 % to 18 %. For the same set of concrete cores, Poisson’s ratios were measured in the range of 0.16 to 0.23 by the OSR tests, which indicated that Poisson’s ratio could be dependent upon on the physical conditions of drilled cores. Variability of Poisson’s ratio added uncertainty to the reliability of the impact-echo test. Therefore, it is clear that the RS technique provides more accurate and reliable evaluation of pavement thickness than the impact-echo tests in the tested pavement sections.

Determination of Shear-Wave Velocity

The comparison of the RS tests at pavements and the OSR tests for drilled cores shows that the shear-wave velocities measured at pavements are approximately 3.6 % larger than the shear-wave velocities measured for drilled cores. The difference in shear-wave velocities may be attributed to the difference in the measurement method for shear-wave velocity and also to the in-situ stresses applied to the tested material. Based on the proven reliability of the SASW method, the difference between pavement velocity and core velocity is mainly due to in-situstress conditions induced by the lateral confinement of concrete material. Usually lateral confinement increases the mean principal pressure, which increases stiffness of material, too. Therefore, the larger shear-wave velocity at pavements implies that field strength of concrete pavements may be larger than laboratory strength of drilled cores.

Relationship between Velocity and Strength

Finally, the correlations between shear-wave velocity and compressive strength were established. Figure 8(a) shows relationships between shear-wave velocities and compressive strengths. In general, each of the tested sites shows the similar trend of increasing strength with increasing velocity. A typical best-fit function of Eq. 1 was used to draw the relationship between shear-wave velocity ( Sv ) and compressive strength ( cf ) for each site, independently.

bwaterPSc vvaf )/( ,⋅= (1)

In case of YoungDong highway pavements, coefficient a is 115.0 kg/cm2 and coefficient b is 3.066, where waterPv , is P-wave velocity of water, 1,500 m/sec. In Figure 8(a), a similar trend

between YoungDong highway pavements and Gimpo airport pavements is observed, but a very different trend is shown for Seohaean highway pavements. From these trends, it can be clearly seen that the velocity-strength relationship is site-specific. Using a limited number of drilled cores, the site-specific relationships between shear-wave velocity and compressive strength were built for YoungDong express highway pavements, Seohaean express highway pavements and Gimpo airport pavements. And the relationships were applied to the shear-wave velocities determined by the RS tests at three sites, as shown in Figure 8(b). For example, the estimated strength ranges from 442.0 to 593.0 kg/cm2 for YoungDong highway pavements. The same relationship developed from the drilled cores can be applied to other pavement sections, once they were constructed using the same concrete mix and curing conditions.

SUMMARY AND CONCLUSIONS

A nondestructive procedure was proposed to evaluate in-place strength of concrete pavements. The proposed procedure consists of three tasks: 1. determination of the site-specific relationship


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between shear-wave velocity and compressive strength, using field-cured cylinders or drilled cores, 2. measurement of shear-wave velocity profile of pavements, 3. conversion of shear-wave velocity profile to strength profile. The use of shear waves in the proposed procedure improved the reliability of strength estimation, and also simplified the analysis procedure without losing accuracy. Also, the new RS technique enhanced the reliability of thickness evaluation significantly.

For the verification of feasibility and reliability, the proposed procedure was applied to highway pavements and airport pavements. Along with the RS tests, a limited number of cores were drilled at the same pavement sections. The drilled cores were used to measure pavement thickness, shear-wave velocity of concrete material and compressive strength. In both thickness and shear-wave velocity evaluation, the RS technique proved to be accurate and reliable. The average errors were 3.3 % and 3.6 % in thickness and shear-wave velocity evaluation, respectively. On the other hand, in thickness evaluation, the impact-echo method had an average error range from 5.2 % to 7.0 %, dependent upon Poisson’s ratio.

The velocity-strength relationship for shear waves turned out to be similar to the one for compression waves. Strength increases geometrically with increasing shear-wave velocities. Independent relationships between shear-wave velocity and compressive strength could be determined from drilled cores for different pavements. The relationship between shear-wave velocity and compressive strength were in a consistent correlation, once the measurements comefrom the same pavement sections with the same concrete mix and curing conditions.

The proposed procedure is not a complete solution for the evaluation of in-place strength and thickness of concrete pavements. The procedure contributed to the advancement of nondestructive evaluation of pavement strength in that the approach based on shear waves and the RS technique can provide a reliable and practical tool in strength profiling of concrete pavements.

ACKNOWLEDGEMENTS

This work was part of the project “Development of Long-Lasting and Environmental-Friendly Materials and Design-Build Technologies for the Pavement” supported by Korea MOCT and KICTTEP. Its financial support is gratefully acknowledged.

REFERENCES

1. Stokoe, K.H., II, S.G. Wright, J.A. Bay, and J.M. Roesset. Characterization of geotechnical sites by SASW method. Geophysical Characteristics of Sites, ISSMFE, Technical Committee 10 for XIII ICSMFE, International Science Publishers, New York, 1994, pp. 15-25.

2. Heisey, S., K. H. Stokoe, II, and A. H. Meyer. Moduli of Pavement Systems from Spectral Analysis of Surface Waves. In Transportation Research Record 852, TRB, National Research Council, Washington, D.C. 1988., pp.22-31.

3. Nazarian S. and K. H. Stokoe, II. Nondestructive Testing of Pavements Using Surface Waves. In Transportation Research Record 993, TRB, National Research Council, Washington, D.C. 1984., pp.132-144.


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4. Nazarian S., K. H. Stokoe, II, R. C. Briggs, and R. Rogers. Determination of Pavement Layer Thicknesses and Moduli by SASW Method. In Transportation Research Record 1196, TRB, National Research Council, Washington, D.C. 1988.

5. Nazarian S. and K. H. Stokoe, II. Nondestructive Evaluation of Pavements by Surface Wave Method. In Nondestructive Testing of Pavements and Backcalculation of Moduli, STP 1026, A.J. Bush III and G. Y. Baladi (eds.), ASTM, Philadelphia, Pa., 1989, pp.119-137.

6. Sheu, J. C., G. J. Rix, and K. H. Stokoe, II. Rapid Determination of Modulus and Thickness of Pavement Surface Layer. Presented at 67th Annual Meeting of the Transportation Research Board, Washington, D.C., Jan. 1988.

7. Hiltunen, D. R. and R. D. Woods. Variables Affecting the Testing of Pavements by the Surface Waves Method. In Transportation Research Record 1260, TRB, National Research Council, Washington, D.C. 1990.

8. Roesset, J. M., D.-W. Chang, K. H. Stokoe, II, and M. Aouad. Modulus and Thickness of the Pavement Surface Layer from SASW Tests. In Transportation Research Record 1260, TRB, National Research Council, Washington, D.C. 1990.

9. Kausel, E. and J. M. Roesset. Stiffness matrices for Layered Soil. Bulletin of the Seismological Society of America, Vol. 71, No. 6, Dec. 1981, pp.1743-1761.

10. Roesset J.M., D. W. Chang D.W., and K. H. Stokoe, II. Comparison of 2-D and 3-D models for analysis of surface wave tests, Proc. 5th Int. Conf. on Soil Dyn. and Earthq. Eng., Kalsruhe, vol. 1, 1991. pp. 111-126

11. Sansalone, M., and N. J. Carino. Impact Echo: A Method for Flaw Detection in Concrete Using Transient Stress Waves. NBSIR 86-3452. National Technical Information Service, Springfield, Va., Sept., 1986, 222 pp.

12. Sansalone M. J., W. B. Streett, IMPACT-ECHO: Nondestructive Evaluation of Concrete and Masonry. Bullbrier Press, 1997 p.339.

13. Cho, M.-R. Development of a Seismic Method for the Nondestructive Integrity Assessment of Concrete Structures. Ph.D. Dissertation, Chung-Ang University, 2002.

14. Sansalone M. J., J. M. Lin, and W. B. Streett. A New Procedure for Determining the Thickness of Concrete Highway Pavements Using Surface Wave Speed Measurements and the Impact-Echo Method, In Innovations in Nondestructive Testing, a Special Publication of the American Concrete Institute. 1996.

15. Nazaraian, S., D. Yuan, E. Weissinger, and M. McDaniel. Comprehensive Quality Control of Portland Cement Concrete with Seismic Methods. In Transportation Research Record 1575, TRB, National Research Council, Washington, D.C. 1997. pp. 102-111.

16. Nazaraian, S., D. Yuan, and M. R. Baker. Quality Control of Portland Cement Concrete Slabs with Wave Propagation Technique. In Transportation Research Record 1544, TRB, National Research Council, Washington, D.C. 1996. pp. 91-98.

17. Parker, W. E. Pulse Velocity Testing of Concrete, Proceedings, American Society for Testing Materials, Vol. 53, 1953. pp. 1033-1042.

18. Malhotra, V. M. and G. G. Carette. Comparison of Pullout Strength of Concrete with Compression Strength of Cylinders and Cores, Pulse Velocity, and Rebound Number, ACI Journal, Vol. 77, No. 3, 1980. pp. 17-31.

19. Sturrup, V. R.,, F. J. Vecchio and H. Caratin, Pulse Velocity as a Measure of Concrete Compressive Strength, In-Situ Nondestructive Testing of Concrete, SP-82, V. M. Malhotra, ed., American Concrete Institute, Farmington Hills, Michigan, 1984. pp. 201-227.


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20. Pesski, S. and M. R. Johnson, Nondestructive Evaluation of Early-Age Concrete Strength in Plate Structures by the Impact-Echo Method, ACI Materials Journal, Vol. 93, No. 3, 1996. pp. 260-271.

21. Cho, M. R., K. B. Kim, B. S. Park, and C. K. Hong. The Optimized Shear-Wave Resonance Technique to Measure Shear-Wave Velocities of Cylinders and Cores. Submitted for Journal of KCI. 2006.

22. Joh, S.-H. Advances in Interpretation and Analysis Techniques for Spectral-Analysis-of-Surface-Waves (SASW) Method. Ph.D. Dissertation, The University of Texas at Austin, 1996.


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FIGURE 1 Correlation between shear-wave velocity and strength of concrete material determined by the optimized shear-wave resonance (OSR) tests: (a) measurement configuration of the OSR tests, (b) typical correlation between shear-wave velocity and compressive strength.

FIGURE 2 Procedure to assess the strength profile of concrete pavements by combination of laboratory and field tests.

FIGURE 3 Procedure of the resonance search technique for the determination of slab thickness as well as shear-wave velocity profile with accuracy.

FIGURE 4 Numerical simulation of the RS measurements for a concrete pavement.

FIGURE 5 The RS measurements at the concrete pavement of Seohaean express highway: (a) measurement hardware, (b) amplitude spectrum of transfer function between accelerometer and instrumented hammer, (c) phase spectrum of transfer function between two receivers with 0.3m offset.

FIGURE 6 Interpretation and analysis for the RS measurements at the concrete pavement of Seohaean express highway: (a) resonance search, (b) shear-wave velocity profile adjusted by the RS technique, (c) relationship of shear-wave velocity and compressive strength and (d) strength profile.

FIGURE 7 Comparisons of the proposed RS tests with the direct measurements for drilled cores: (a) thickness and (b) average shear-wave velocities of concrete pavements.

FIGURE 8 Compressive strength of concrete pavements evaluated by the proposed RS technique: (a) data used for the development of velocity-strength relationship and (b) compressive strengths estimated for all the measured shear-wave velocities.


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600

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FIGURE 1 Correlation between shear-wave velocity and strength of concrete material determined by the optimized shear-wave resonance (OSR) tests: (a) measurement configuration for torsional-shear wave measurements (b) measurement configuration for compression wave measurements, (c) typical amplitude spectra of shear and compression waves, (d) typical correlation between shear-wave velocity and compressive strength.


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Laboratory Test Field Test

Shear-Wave Velocity:

Determined byOptimized S-Wave Resonance (OSR) Tests.

1. Determination of Relationship betweenShear-Wave Velocity and Strength.

2. Measurement ofShear-Wave Velocity Profile of Pavement.

3. Conversion ofShear-Wave Velocity Profile to Strength profile.

S-Wave Velocity Profile:

Determined byResonance Search (RS) Technique

FIGURE 2 Procedure to assess the strength profile of concrete pavements by combination of laboratory and field tests.


14

Determine fR

: the resonant frequency of acceleration/displacement spectrum at receiver 1 or transfer function.

Phase 1: Determination of Shear-Wave Velocity Profile

Determine λR

: wavelength for the resonant frequency

RR d φλ /360ο=

Determine φR

: phase angle for the resonant frequency

Determine vS

: the S-wave velocity profile of a concrete slab by inversion analysis* by assuming pavement thickness, h = λR.

*Joint-inversion analysis of vS and h based on the array inversion algorithm.

Determine h: thickness of a concrete pavement by the RS technique, based on the wave-propagation modeling for slabs with different thicknesses.

Phase 2: Resonance Search for Thickness Determination

measured resonant frequency, fR

0.34

0.32

0.30

0.28

0.26

0.24

0.22

0.20

Pav

emen

t Thi

ckne

ss, m

5x103 6 7 8

Resonance Frequency, Hz

6012 Hz

0.299 m

Determine fR

: the resonant frequency of acceleration/displacement spectrum at receiver 1 or transfer function.

Phase 1: Determination of Shear-Wave Velocity Profile

Determine λR

: wavelength for the resonant frequency

RR d φλ /360ο=

Determine φR


Determine φR


Determine vS

: the S-wave velocity profile of a concrete slab by inversion analysis* by assuming pavement thickness, h = λR.

*Joint-inversion analysis of vS and h based on the array inversion algorithm.

Determine h: thickness of a concrete pavement by the RS technique, based on the wave-propagation modeling for slabs with different thicknesses.

Phase 2: Resonance Search for Thickness Determination

measured resonant frequency, fR

0.34

0.32

0.30

0.28

0.26

0.24

0.22

0.20

Pav

emen

t Thi

ckne

ss, m

5x103 6 7 8


0.34

0.32

0.30

0.28

0.26

0.24

0.22

0.20

Pav

emen

t Thi

ckne

ss, m

5x103 6 7 8


6012 Hz

0.299 m

FIGURE 3 Procedure of the resonance search technique for the determination of pavementthickness as well as shear-wave velocity profile.


15

3.0x10-10

2.5

2.0

1.5

1.0

0.5

0.025x10

320151050

Frequency, Hz

6012 Hz

-150

-100

-50

0

50

100

150

25x103

20151050Frequency, Hz

Original IRF-Enhanced

ο3.390=φmd 277.0/360max == φλ ο

(a)

(b)

masked out

Pha

se A

ngle

of

Tra

nsfe

r F

unct

ion,

deg

Line

ar S

pect

rum

of

Dis

plac

emen

t at R

ec. 1

2500

2000

1500

1000

500

0

Pha

se V

eloc

ity, m

/sec

0.300.250.200.150.100.05Wavelength, m

Raw Data Representative

(Input for Inv. Analysis) Theoretical

(Results of Inv. Analysis)

(c)

m277.0max =λ

2500

2000

1500

1000

500

0

Pha

se V

eloc

ity, m

/sec

0.300.250.200.150.100.05Wavelength, m

Raw Data Representative

(Input for Inv. Analysis) Theoretical

(Results of Inv. Analysis)

(c)

m277.0max =λ

0.4

0.3

0.2

0.1

0.0

Dep

th, m

300025002000150010005000Shear-Wave Velocity, m/sec

(d)VS,1 =1504 m/sec

VS,2=2403 m/sec

H1=0.051 m

H2=0.223 m

H0=

0.27

4 m

0.4

0.3

0.2

0.1

0.0

Dep

th, m


(d)VS,1 =1504 m/sec

VS,2=2403 m/sec

H1=0.051 m

H2=0.223 m

H0=

0.27

4 m

1.0x10-10

0.8

0.6

0.4

0.2

0.0S

pect

ral D

ispl

., m

800070006000500040003000Frequency, Hz

H=0.8 Η0=0.219 m

H=0.9 Η0=0.247 mH= Η0=0.274 m

H=1.1 Η0=0.301 m

H=1.2 Η0=0.329 m

(e)

1.0x10-10

0.8

0.6

0.4

0.2

0.0S

pect

ral D

ispl

., m

800070006000500040003000Frequency, Hz

H=0.8 Η0=0.219 m

H=0.9 Η0=0.247 mH= Η0=0.274 m

H=1.1 Η0=0.301 m

H=1.2 Η0=0.329 m

(e)

0.340.320.30

0.28

0.26

0.24

0.22

0.20

Sla

b T

hick

ness

, m

5x103 6 7 8

Resonant Frequency, Hz

6012 Hz

0.299 m(f)

FIGURE 4 Numerical simulation of the RS measurements for a concrete pavement.


16

-150

-100

-50

0

50

100

150

Pha

se A

ngle

of T

rans

fer

Fn.

25x103

20151050

Frequency, Hz

Raw Data Filtered Data

1.2

1.0

0.8

0.6

0.4

0.2

0.0

Nor

mal

ized

Am

plitu

de

25x103

20151050

Frequency, Hz

Power Spectrum (Receiver) Transfer Function

(between Source and Receiver)

(a)

(b)

(c)

fR=5,376 Hz

FIGURE 5 The RS measurements at the concrete pavement of Seohaean express highway: (a) measurement hardware, (b) amplitude spectrum of transfer function between accelerometer and instrumented hammer, (c) phase spectrum of transfer function between two receivers with 0.3m offset.


17

2x10-1

3

4

5

6

7

Pav

emen

t Thi

ckne

ss, m

4x103 5 6 7

Resonant Frequency, Hz

0.349 m

5376 Hz

0.4

0.3

0.2

0.1

0.0

Dep

th, m


800

600

400

200

0

Com

p. S

tren

gth,

kg/

cm2

3000200010000S-Wave Velocity, m/sec

0.4

0.3

0.2

0.1

0.0

Dep

th, m

6004002000Comp. Strength, kg/cm

2

(a) (c)

(d)

(b)

Thickness Adjustmentby the RS Technique

FIGURE 6 Interpretation and analysis for the RS measurements at the concrete pavement of Seohaean express highway: (a) resonance search, (b) shear-wave velocity profile adjusted by the RS technique, (c) relationship of shear-wave velocity and compressive strength and (d) strength profile.


18

0.5

0.4

0.3

0.2

0.1

0

Eva

luat

ed P

avem

ent T

hick

ness

, m

0.50.40.30.20.10.0

Length of Drilled Cores, m

RS: YoungDong Express Highway RS: Seohaean Express Highway IE (ν=0.17): Seohaean Express Highway IE (ν=0.23): Seohaean Express Highway

*Note. RS: Resonance Search Technique IE: Impact-Echo Test

3500

3000

2500

2000

1500

1000

500

0

S-W

ave

Vel

ocity

by

the

RS

Tec

hniq

ue, m

/sec

3500300025002000150010005000

S-Wave Velocities of Drilled Cores, m/sec

Seohaean Express Highway YoungDong Express Highway Gimpo Airport

(a) (b)

FIGURE 7 Comparisons of the proposed RS tests with the direct measurements for drilled cores: (a) thickness and (b) average shear-wave velocities of concrete pavements.


19

800

600

400

200

0

Est

imat

ed C

ompr

essi

ve S

tren

gth,

kg/

cm2

300025002000150010005000

Shear-Wave Velocities by the RS Technique, m/sec


800

600

400

200

0

Com

pres

sive

Str

engt

h, k

g/cm

2

300025002000150010005000

Shear-Wave Velocities of Drilled Cores, m/sec


(a) (b)

FIGURE 8 Compressive strength of concrete pavements evaluated by the proposed RS technique: (a) data used for the development of velocity-strength relationship and (b) compressive strengths estimated for all the measured shear-wave velocities.


nondestructive in -place strength profiling of concrete ...docs.trb.org/prp/07-1406.pdf ·...

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