Noninvasive Assessment of Existing Concrete Piervincenzo Rizzo, Amir Nasrollahi, Wen Deng, Julie M. Vandenbossche Laboratory for Nondestructive Evaluation and Structural Health Monitoring studies, Department of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh. USA
Pennsylvania Department of Transportation
2016 Transportation Forum 3-23-16, Pittsburgh, PA
Outline • • •
Project motivation Background Research outline Designed, assembled, and validated new sensing systems Cast concrete cylinders with different w/c ratios Cast concrete short beams with water in excess.
• •
Conclusions Questions and discussion
Laboratory for Nondestructive Evaluation and Structural Health Monitoring studies
Project Motivation • The performance of concrete decks may be affected if during construction excessive water results from rainfall prior or during construction. • There is a need to evaluate nondestructively concrete decks. • This project proposed a new nondestructive evaluation (NDE) method to assess existing concrete surfaces. • The method is based on the propagation of highly nonlinear solitary waves (HNSWs) Laboratory for Nondestructive Evaluation and Structural Health Monitoring studies
Hypothesis and background • We propose to use the propagation of highly nonlinear solitary waves (HNSWs) to quantify the strength of concrete. • HNSWs are compact stress waves that can form and travel in highly nonlinear systems (i.e. granular, layered, fibrous or porous materials). • The most common example of a medium supporting the formation and propagation of HNSWs is a chain of spherical particles (beads). • The solitary pulse can be excited by impacting one side of the chain with a particle (striker).
Laboratory for Nondestructive Evaluation and Structural Health Monitoring studies
Research hypothesis Free
falling striker 1 2
n-2
• We hypothesize that the n TOF and the amplitude ratio of the reflected solitary wave are indirectly correlated to the properties of the concrete. cheme of structural assessment by means of HNSWs.
Dynamic force (N)
n-1
9.0 8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0.0 -1.0
Incident wave
0
100
200
Reflected wave
300 400 Time (microsec)
500
600
Laboratory for Nondestructive Evaluation and Structural Health Monitoring studies
Research carried • • •
Designed, assembled, and validated new sensing systems Cast concrete cylinders with different w/c ratios Cast concrete short beams with water in excess.
Laboratory for Nondestructive Evaluation and Structural Health Monitoring studies
Transducers development • Two new sensing systems Two new sensing systems: magnetostrictive-based
(MsS) and piezoelectric-based (PZT) Each transducers consisted of a chain of spheres made of stainless steel particles with D = 19.05 mm and m = 29 gr. The pulse is generated by the impact of a striker The striker is driven by an electromagnet
(a)
Electromagnet
Electromagnet
Striker
Striker
Granular Chain
Granular Chain Magnetostrictive Sensor
Positive (+) PZT Sensor
Window Negative (-)
Delrin Acetal Resin Tube
Aluminum Plate Specimen
Delrin Acetal Resin Tube
Aluminum Plate Specimen
Laboratory for Nondestructive Evaluation and Structural Health Monitoring studies
Experimental setup
For each kind of transducers, four transducers were designed and assembled An electromagnet was used to drive the striker. The electromagnet was driven by a NI-PXI running in LabVIEW. MsS were use to sense the waves.
Laboratory for Nondestructive Evaluation and Structural Health Monitoring studies
Experimental setup
Eight concrete slabs were tested. The four transducers were placed above four different locations of the slab. For each transducer, we collected 100 measurements to increase the statistical population and investigate the repeatability of the setup. We estimated the ultimate strength and the modulus of the concrete using conventional destructive tests.
Laboratory for Nondestructive Evaluation and Structural Health Monitoring studies
Transducers development Example of MsS-based: time series of the integrated voltage signal. • The results refer to a slab • Each time waveform is the average of the 100 time waveforms. • One feature is discussed here: the time of flight (TOF) relative to the primary reflected wave Voltage integral
•
0
sensor1 sensor2 sensor3 sensor4
10 V.Sec
1
2 3 Time (ms)
4
5
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Research carried • •
Designed, assembled, and validated new sensing systems Conclusions
Both types of transducers are robust and provides repeatable measurements within a standard deviation of 2% from the average value The PZT-based is less bulky The MsS-based can be placed anywhere along the chain
(a)
• Cast concrete cylinders with different w/c ratios • Cast concrete short beams with water in excess.
Electromagnet
Electromagnet
Striker
Striker
Granular Chain
Granular Chain Magnetostrictive Sensor
Positive (+) PZT Sensor
Window Negative (-)
Delrin Acetal Resin Tube
Aluminum Plate Specimen
Delrin Acetal Resin Tube
Aluminum Plate Specimen
Laboratory for Nondestructive Evaluation and Structural Health Monitoring studies
Cast concrete cylinders: setup
Table 1a. The material used in the concrete mixtures Material Specific gravity Water absorption capacity (%) 3.15 n/a used in the concrete mixtures Cement Table 1a. The material 2.71 Material 0.50 Coarse aggregate Specific gravity Water absorption capacity (% 2.67 Cement 1.24 Fine aggregate Table 1a. The material used 3.15 in the concrete mixtures n/a 2.83 n/a GGBFS1 2.71 0.50 Coarse aggregate Material Specific gravity Water absorption capacity (%) 1 ground-granulated blast-furnace slag 2.67 1.24 Fine aggregate 3.15 n/a Cement 2.83 n/a GGBFS1 2.71 0.50 Coarse aggregate 1 ground-granulated blast-furnace slag 2.67 1.24 Fine aggregate 2.83 n/a GGBFS1 1 Table 1b. The ingredients of each concreteblast-furnace batch ground-granulated slag Batch 1 2 3 0.42 0.45 0.50 w/c ratio Table 1b. The ingredients of each concrete batch 0.30 Paste vol./concrete vol. 0.30 0.30 Batch 1 2 3 6.50 5.00 6.25 Air contentTable (%) 1b. The ingredients of each concrete 0.42batch 0.45 0.50 w/c ratio 1054 1054 Coarse agg. (kg/m3) Batch 1 vol. 2 0.30 3 0.30 0.30 Paste1054 vol./concrete 666 666 Fine agg. (kg/m3) w/c666 0.42 ratioAir content (%) 0.456.500.505.00 6.25 3 303 291 Cement (kg/m ) 0.30 3) 0.301054 0.301054 1054 Paste vol./concrete vol. Coarse agg.274 (kg/m 101 Fine 97 91 GGBFS (kg/m3) Air content 6.503) 5.00 6666.25 666 (%)agg. (kg/m 666 170 (kg/m 1753) (kg/m 183 Water (kg/m3Coarse ) 10543) 10543031054291 agg. 274 Cement 3 3 133(kg/m 95 203 Slump (mm) Fine agg. 666 666 666 ) 101 97 91 GGBFS (kg/m )
• Three w/c ratios considered
Evaluated the ability of the new NDE method at detecting differences among the cylinders. The same specimes were tested with conventional ultrasonic method (UPV) Half of the test specimens were 303) 291 170274 175 Cement (kg/m ) (kg/m 183 Water 101 97 133 91 95 GGBFS (kg/m ) 203 Slump (mm) destructively loaded using ASTM 170 175 183 Water (kg/m ) 133 95 203 Slump (mm) Table 1c. The detailed information of the concrete cylinders. The samples evaluated with the NDE method C469 were wet and tested after 27 days with the M-transducers, 28 days with the P-transducers, and 29 days with 3
3
3
3
the UPV of curing. The samples subjected to compressive load were tested saturated after 28 days of curing Table 1c. The detailed information of the concrete cylinders. The samples evaluated w of after 27 days NDEwith the M-transducers, ASTM C469 28 days with the P-transduc were wetNumber and tested w/c ratio cylinders sample labels sample labelsload were tested saturated af the detailed UPV of curing. The samples subjected to compressive Table 1c. The information of the concrete cylinders. The samples evaluated with the NDE 0.42 6 42A, 42B, 42C 42D, 42E, 42F Number of 28 days with NDEthe P-transducers, ASTMand C469 were wet and tested after 27 days with the M-transducers, 29 w/c45A, ratio45B, 45C 0.45 6 45E, 45F labels cylinders45D, sample labels the UPV of curing. The samples subjected to compressive load were tested saturatedsample after 28 days 0.50 6 50A, 50B, 50C 6 50D, 50E, 50F 42C 0.42 42D, 42E, 42F Number of NDE 42A, 42B,ASTM C469 w/c ratio 0.45 6sample labels 45A, 45B,sample 45C labels 45D, 45E, 45F cylinders 0.50 6 642A, 42B, 42C 50A, 50B,42D, 50C 42E, 42F 50D, 50E, 50F 0.42 0.45 6 45A, 45B, 45C 45D, 45E, 45F Laboratory for Nondestructive Evaluation 0.50 6 50A, 50B, 50C 50D, 50E, 50F
and Structural Health Monitoring studies
Cast concrete cylinders: results • Three w/c ratios considered ďƒź Evaluated the ability of the new NDE method at detecting differences among the concrete cylinders. (a)
(b)
Magnetostriction
(c)
(d)
Piezoelectric
Laboratory for Nondestructive Evaluation and Structural Health Monitoring studies
Cast concrete cylinders: results • We developed a numerical method to link some features of the HNSWs to the mechanical properties of concrete.
(d)
(a)
(b)
Figure 11. Numerical model. (a) TOF as a function of the dynamic modulus of elasticit ratio of the material in contact with the chain of spherical particles; (b) TOF as a functi Laboratory for elasticity Nondestructive Evaluation when ν=0.20.
and Structural Health Monitoring studies
Cast concrete cylinders: results • Young’s modulus associated with the four methodologies investigated here. • The novel NDE method was able to predict the elastic modulus of the concrete cylinders with more accuracy than the conventional ultrasonic method.
Laboratory for Nondestructive Evaluation and Structural Health Monitoring studies
Research carried • Designed, assembled, and validated new sensing systems • Cast concrete cylinders with different w/c ratios The new method was able to ascertain the Young’s modulus of the concrete cylinders with three different w/c ratios.
• Cast concrete short beams with water in excess.
Laboratory for Nondestructive Evaluation and Structural Health Monitoring studies
Short concrete beams: setup • Sixteen 6 in. × 6 in. × 12 in. beams were fabricated using concrete mix design with w/c=0.42. • The beams were subject to the four different scenarios. Each scenario represented either two surface finishing or two standing water situations in the formworks.
• Conditions 1 and 2 reflected the case where water accumulates on the formwork as a result of rainfall prior to the placement of the concrete. • Conditions 3 and 4 simulated the occurrence of rainfall during placement and finishing of the concrete. Laboratory for Nondestructive Evaluation and Structural Health Monitoring studies
Short concrete beams: photos setup
1 2 of Fig. 3.13 Pouring standing water in bottom prepared beam molds (condition 1) 3 4 5
Fig. 3.33 First application of surface water (condition 4)
Figure 2. Photos of the preparation of the samples. (a) Close-up view of one of the samples under condition 2; standing water from bottom of beam mold migrates to the top. (b) Preparation of one of the samples under condition 3: finishing beam surface after second application of water. (c) Rodding the same sample shown in (b) during the third and final application of surface water.
Laboratory for Nondestructive Evaluation and Structural Health Monitoring studies
Short concrete beams: results (f)
•
For the sake of brevity only the results relative to the PZT-based are presented.
(e)
(g)
(f)
(h)
1
(g)
Short concrete beams: results Rainfall prior construction
Cast day
Sample
Average E (GPa) Short beam w/c=0.42
1 2 Figure 2. Photos of the preparation of the samples. (a) Close-up view of one of the samples under Top to the top. (b) Bottom 3 Top condition Bottom 2; standing water from bottom of beam mold migrates Preparation of one Cast day Sample TOF (ms) E (GPa) TOF (ms) E (GPa) TOF (ms) E (GPa) TOF (ms) E (GPa) 4 of the samples under condition 3: finishing beam surface after second application of water. (c) Average E (GPa) 29.83 ± 7.08 (23.73%) 35.33 ± 4.37 (12.35%) 29.58 ± 6.02 (20.35%) 37.17 ± 6.24 (16.80%) Short beam w/c=0.42 5 Rodding the same sample shown in (b) during the third and final application of surface water.
Cylinder w/c=0.42
41.1 ± 1.389 (3.38%)
Cylinder w/c=0.42
41.1 ± 1.389 (3.38%)
Cylinder w/c=0.45
37.6 ± 1.815 (4.82%)
Cylinder w/c=0.45
37.6 ± 1.815 (4.82%)
Cylinder w/c=0.50
31.8 ± 1.907 (6.00%)
Cylinder w/c=0.50
31.8 ± 1.907 (6.00%)
1
Short concrete beams: results Rainfall during construction
Cast day
Sample
Average E (GPa) Short beam w/c=0.42
Top TOF (ms)
Bottom E (GPa)
31.83 ± 5.07 (15.96%)
TOF (ms)
E (GPa)
39.25 ± 3.394 (8.650%)
Cylinder w/c=0.42
41.1 ± 1.389 (3.38%)
Cylinder w/c=0.45
37.6 ± 1.815 (4.82%)
Cylinder w/c=0.50
31.8 ± 1.907 (6.00%)
1
Cast day
Sample
Average E (GPa) Short beam w/c=0.42
Top TOF (ms)
Bottom E (GPa)
30.92 ± 5.107 (16.52%)
TOF (ms)
E (GPa)
38.67 ± 3.37 (8.73%)
Cylinder w/c=0.42
41.1 ± 1.389 (3.38%)
Cylinder w/c=0.45
37.6 ± 1.815 (4.82%)
Cylinder w/c=0.50
31.8 ± 1.907 (6.00%)
Short concrete beams: conclusions • Designed, assembled, and validated new sensing systems • Cast concrete cylinders with different w/c ratios • Cast concrete short beams with water in excess. The new method was able to ascertain the Young’s modulus of the concrete cylinders with three different w/c ratios.
Laboratory for Nondestructive Evaluation and Structural Health Monitoring studies
Conclusions • •
•
Presented a novel nondestructive evaluation method to infer strength of concrete. Found a promising agreement between the results with our method and the values found using conventional destructive methods. Developed (but not shown here) an analytical model to predict the response of solitary waves interfacing concrete and other materials with different Young’s modulus and Poisson’s ratio.
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Publications Deng, W., Nasrollahi, A., Rizzo, P., and Li, K. (2016) “On the Reliability of a Solitary Wave Based Transducer to Determine the Characteristics of some Materials,” Sensors, 16(5); doi:10.3390/s16010005, 19 pages. • Rizzo, P., Nasrollahi, A., Deng, W., and Vandenbossche, J.M. (2016) “Detecting the presence of high water-to-cement ratio in concrete surfaces using highly nonlinear solitary waves ,” Applied Sciences. Featured article in the special issue: Acoustic and Elastic Waves: Recent Trends in Science and Engineering, tentatively accepted, under 2nd round of review. • Nasrollahi, A., Deng, W., Rizzo, P., Vuotto, A., Vandenbossche, J.M., and Li, K. (2016) “Highly nonlinear solitary waves to estimate the modulus of concrete with different water-to-cement ratios,” In preparation. • Rizzo, P. (2016). Noninvasive Assessment of Existing Concrete, Final Report submitted to the Federal Railroad Administration under Contract No. 4400011482, Work Order No. PIT 008. •
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Acknowledgement •
The project was supported by Pennsylvania Department Of Transportation (PennDOT)
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We appreciate Dr. Vandenbossche’s research group for their contribution in preparing the samples and conductiong destructive tests.
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Thanks to colleagues in Laboratory for Nondestructive Evaluation and Structural Health Monitoring Studies, Dr. Pervincenzo Rizzo (Ph.D.), Wen Deng, Kaiyuan Li, and Dr. Abdollah Bagheri (Ph.D.)
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QUESTIONS?