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Embedded ultrasonic transducers for active and passive concrete monitoring.

Niederleithinger E, Wolf J, Mielentz F, Wiggenhauser H, Pirskawetz S - Sensors (Basel) (2015)

Bottom Line: The transducer design, the main properties as well as installation procedures are presented.Application examples demonstrate that the transducers can be used to monitor concrete conditions parameters (stress, temperature, …) as well as damages in an early state or the detection of acoustic events (e.g., crack opening).Besides application in civil engineering our setups can also be used for model studies in geosciences.

View Article: PubMed Central - PubMed

Affiliation: BAM Federal Institute for Materials Research and Testing, Berlin 12200, Germany. ernst.niederleithinger@bam.de.

ABSTRACT
Recently developed new transducers for ultrasonic transmission, which can be embedded right into concrete, are now used for non-destructive permanent monitoring of concrete. They can be installed during construction or thereafter. Large volumes of concrete can be monitored for changes of material properties by a limited number of transducers. The transducer design, the main properties as well as installation procedures are presented. It is shown that compressional waves with a central frequency of 62 kHz are mainly generated around the transducer's axis. The transducer can be used as a transmitter or receiver. Application examples demonstrate that the transducers can be used to monitor concrete conditions parameters (stress, temperature, …) as well as damages in an early state or the detection of acoustic events (e.g., crack opening). Besides application in civil engineering our setups can also be used for model studies in geosciences.

No MeSH data available.


Related in: MedlinePlus

Concrete specimen GK32 with embedded transducers and load application system. From [26].
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sensors-15-09756-f010: Concrete specimen GK32 with embedded transducers and load application system. From [26].

Mentions: A 1.5 × 1.5 × 1.5 m3 concrete block (“GK32”) has been cast in the BAM labs for various tests of the embedded ultrasonic transducers (Figure 10). The lower half contains a certain amount of reinforcement, the upper one is unreinforced. A total number of 18 ultrasonic transducers have been embedded, partly during partly after casting the block. Just ten of those have been used for a load monitoring experiment due to limitation of the available data acquisition equipment. The experiment has already been described in more detail in [26]. A two channel multiplexer had connected the transducers to an ultrasonic transmitter (rectangle, 50 kHz) or data recording system, respectively. All 90 transducer combinations could be interrogated within seconds or minutes, depending on the number of repetitions. In the upper half of the concrete block a hole was drilled to insert a thread bolt. Some of the transducers have been just a few cm away from the center of the load, some almost 1 m. Nuts, 10 × 10 cm2 load distributing plates and a piezo load cell provided a way to introduce localized compressional stress in a controlled, repeatable way. Direction of the main compressional load is perpendicular to the front surface shown in Figure 10. However, stresses parallel to the front face are generated as well. Load steps of 5 or 10 kN were applied in various cycles up to a maximum load between 20 and 100 kN, more than one order of magnitude below the compressive strength of the concrete.


Embedded ultrasonic transducers for active and passive concrete monitoring.

Niederleithinger E, Wolf J, Mielentz F, Wiggenhauser H, Pirskawetz S - Sensors (Basel) (2015)

Concrete specimen GK32 with embedded transducers and load application system. From [26].
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4481983&req=5

sensors-15-09756-f010: Concrete specimen GK32 with embedded transducers and load application system. From [26].
Mentions: A 1.5 × 1.5 × 1.5 m3 concrete block (“GK32”) has been cast in the BAM labs for various tests of the embedded ultrasonic transducers (Figure 10). The lower half contains a certain amount of reinforcement, the upper one is unreinforced. A total number of 18 ultrasonic transducers have been embedded, partly during partly after casting the block. Just ten of those have been used for a load monitoring experiment due to limitation of the available data acquisition equipment. The experiment has already been described in more detail in [26]. A two channel multiplexer had connected the transducers to an ultrasonic transmitter (rectangle, 50 kHz) or data recording system, respectively. All 90 transducer combinations could be interrogated within seconds or minutes, depending on the number of repetitions. In the upper half of the concrete block a hole was drilled to insert a thread bolt. Some of the transducers have been just a few cm away from the center of the load, some almost 1 m. Nuts, 10 × 10 cm2 load distributing plates and a piezo load cell provided a way to introduce localized compressional stress in a controlled, repeatable way. Direction of the main compressional load is perpendicular to the front surface shown in Figure 10. However, stresses parallel to the front face are generated as well. Load steps of 5 or 10 kN were applied in various cycles up to a maximum load between 20 and 100 kN, more than one order of magnitude below the compressive strength of the concrete.

Bottom Line: The transducer design, the main properties as well as installation procedures are presented.Application examples demonstrate that the transducers can be used to monitor concrete conditions parameters (stress, temperature, …) as well as damages in an early state or the detection of acoustic events (e.g., crack opening).Besides application in civil engineering our setups can also be used for model studies in geosciences.

View Article: PubMed Central - PubMed

Affiliation: BAM Federal Institute for Materials Research and Testing, Berlin 12200, Germany. ernst.niederleithinger@bam.de.

ABSTRACT
Recently developed new transducers for ultrasonic transmission, which can be embedded right into concrete, are now used for non-destructive permanent monitoring of concrete. They can be installed during construction or thereafter. Large volumes of concrete can be monitored for changes of material properties by a limited number of transducers. The transducer design, the main properties as well as installation procedures are presented. It is shown that compressional waves with a central frequency of 62 kHz are mainly generated around the transducer's axis. The transducer can be used as a transmitter or receiver. Application examples demonstrate that the transducers can be used to monitor concrete conditions parameters (stress, temperature, …) as well as damages in an early state or the detection of acoustic events (e.g., crack opening). Besides application in civil engineering our setups can also be used for model studies in geosciences.

No MeSH data available.


Related in: MedlinePlus