Noninvasive Assessment of Existing Concrete

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

• Conclusions

• Questions and discussion

Laboratory for Nondestructive Evaluation

and Structural Health Monitoring studies

Designed, assembled, and validated new sensing systems

Cast concrete cylinders with different w/c ratios

Cast concrete short beams with water in excess.

Project Motivation

• 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)



• The performance of concrete decks may be affected if during construction

excessive water results from rainfall prior or during construction.

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).



-1.0

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

0 100 200 300 400 500 600

Dynam

ic f

orc

e (N

)

Time (microsec)

Incident

wave Reflected

wave



Research hypothesis

• We hypothesize that the

TOF and the

amplitude ratio of the

reflected solitary wave

are indirectly correlated

to the properties of the

concrete.

Figure 2 – General scheme of structural assessment by means of HNSWs.

1

2

n-2

n-1

n

Free

falling

striker

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.



Transducers development • Two new sensing systems



Specimen

Electromagnet

Striker

Aluminum

Plate

Magnetostrictive

Sensor

Granular

Chain

Delrin

Acetal

Resin Tube

Specimen

Electromagnet

Striker

Aluminum

Plate

PZT Sensor

Granular

Chain

Delrin

Acetal

Resin Tube

Positive (+)

Negative (-)

Window

(a)

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



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.

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.



• 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

0 1 2 3 4 5Time (ms)

Vo

ltag

e i

nte

gra

l

sensor1

sensor2

sensor3

sensor4

10 V.Sec

Transducers development

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



Specimen

Electromagnet

Striker

Aluminum

Plate

Magnetostrictive

Sensor

Granular

Chain

Delrin

Acetal

Resin Tube

Specimen

Electromagnet

Striker

Aluminum

Plate

PZT Sensor

Granular

Chain

Delrin

Acetal

Resin Tube

Positive (+)

Negative (-)

Window

(a)

• Cast concrete cylinders with different

w/c ratios

• Cast concrete short beams with water

in excess.

Cast concrete cylinders: setup



Table 1a. The material used in the concrete mixtures

Material Specific gravity Water absorption capacity (%)

Cement 3.15 n/a

Coarse aggregate 2.71 0.50

Fine aggregate 2.67 1.24

GGBFS1 2.83 n/a

1 ground-granulated blast-furnace slag

Table 1b. The ingredients of each concrete batch

Batch 1 2 3

w/c ratio 0.42 0.45 0.50

Paste vol./concrete vol. 0.30 0.30 0.30

Air content (%) 6.50 5.00 6.25

Coarse agg. (kg/m3) 1054 1054 1054

Fine agg. (kg/m3) 666 666 666

Cement (kg/m3) 303 291 274

GGBFS (kg/m3) 101 97 91

Water (kg/m3) 170 175 183

Slump (mm) 133 95 203

Table 1c. The detailed information of the concrete cylinders. The samples evaluated with the NDE method

were wet and tested after 27 days with the M-transducers, 28 days with the P-transducers, and 29 days with

the UPV of curing. The samples subjected to compressive load were tested saturated after 28 days of curing

w/c ratio Number of

cylinders

NDE

sample labels

ASTM C469

sample labels

0.42 6 42A, 42B, 42C 42D, 42E, 42F

0.45 6 45A, 45B, 45C 45D, 45E, 45F

0.50 6 50A, 50B, 50C 50D, 50E, 50F



Cement 3.15 n/a



GGBFS1 2.83 n/a



Batch 1 2 3

w/c ratio 0.42 0.45 0.50


Air content (%) 6.50 5.00 6.25

Coarse agg. (kg/m3) 1054 1054 1054

Fine agg. (kg/m3) 666 666 666

Cement (kg/m3) 303 291 274

GGBFS (kg/m3) 101 97 91

Water (kg/m3) 170 175 183

Slump (mm) 133 95 203




w/c ratio Number of

cylinders

NDE

sample labels

ASTM C469

sample labels

0.42 6 42A, 42B, 42C 42D, 42E, 42F

0.45 6 45A, 45B, 45C 45D, 45E, 45F

0.50 6 50A, 50B, 50C 50D, 50E, 50F



Cement 3.15 n/a



GGBFS1 2.83 n/a



Batch 1 2 3

w/c ratio 0.42 0.45 0.50


Air content (%) 6.50 5.00 6.25

Coarse agg. (kg/m3) 1054 1054 1054

Fine agg. (kg/m3) 666 666 666

Cement (kg/m3) 303 291 274

GGBFS (kg/m3) 101 97 91

Water (kg/m3) 170 175 183

Slump (mm) 133 95 203




w/c ratio Number of

cylinders

NDE

sample labels

ASTM C469

sample labels

0.42 6 42A, 42B, 42C 42D, 42E, 42F

0.45 6 45A, 45B, 45C 45D, 45E, 45F

0.50 6 50A, 50B, 50C 50D, 50E, 50F

•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

destructively loaded using ASTM

C469

Cast concrete cylinders: results



• Three w/c ratios considered

Evaluated the ability of the new NDE method at detecting

differences among the concrete cylinders.

(a) (b)

(c) (d)

Magnetostriction

Piezoelectric




• We developed a numerical

method to link some features of

the HNSWs to the mechanical

properties of concrete.

Figure 11. Numerical model. (a) TOF as a function of the dynamic modulus of elasticity and the Poisson’s

ratio of the material in contact with the chain of spherical particles; (b) TOF as a function of the modulus of

elasticity when ν=0.20.

(a)

(b)

(c) (d)




• 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.

Research carried • Designed, assembled, and validated new sensing systems


The new method was able to ascertain the Young’s modulus

of the concrete cylinders with three different w/c ratios.




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.

Short concrete beams: photos setup



1 Figure 2. Photos of the preparation of the samples. (a) Close-up view of one of the samples under 2

condition 2; standing water from bottom of beam mold migrates to the top. (b) Preparation of one 3

of the samples under condition 3: finishing beam surface after second application of water. (c) 4

Rodding the same sample shown in (b) during the third and final application of surface water. 5

Fig. 3.13 Pouring standing water in bottom of

prepared beam molds (condition 1)

Fig. 3.33 First application of surface water

(condition 4)

• For the sake of brevity only the results relative to the PZT-based are presented.

Short concrete beams: results

1

(e)

(f)

(g)

(h)

1

(e)

(f)

(g)

(h)

Rainfall prior construction


Cast day Sample Top Bottom

TOF (ms) E (GPa) TOF (ms) E (GPa)

Average E (GPa)

Short beam w/c=0.42 29.83 ± 7.08 (23.73%) 35.33 ± 4.37 (12.35%)

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



Average E (GPa)

Short beam w/c=0.42 29.58 ± 6.02 (20.35%) 37.17 ± 6.24 (16.80%)

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

1 Figure 2. Photos of the preparation of the samples. (a) Close-up view of one of the samples under 2

condition 2; standing water from bottom of beam mold migrates to the top. (b) Preparation of one 3

of the samples under condition 3: finishing beam surface after second application of water. (c) 4

Rodding the same sample shown in (b) during the third and final application of surface water. 5

Rainfall during construction




Average E (GPa)

Short beam w/c=0.42 31.83 ± 5.07 (15.96%) 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



Average E (GPa)

Short beam w/c=0.42 30.92 ± 5.107 (16.52%) 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%)

1

• Designed, assembled, and validated new sensing systems





Short concrete beams: conclusions

The new method was able to ascertain the Young’s modulus

of the concrete cylinders with three different w/c ratios.

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.



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.



Acknowledgement • The project was supported by Pennsylvania Department Of

Transportation (PennDOT)

• We appreciate Dr. Vandenbossche’s research group for their

contribution in preparing the samples and conductiong destructive

tests.

• 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.)



QUESTIONS?

Documents

Noninvasive Assessment of Existing Concrete