Overview
ISO 16838:2019 defines a test method using acoustic emission (AE) to classify active cracks in concrete structures. The standard supports non-destructive testing (NDT) workflows for assessing damage evolution in reinforced concrete and for prioritizing maintenance decisions. It builds on established AE calibration and terminology standards and describes measurement systems, environmental noise mitigation, test procedures and reporting requirements.
Keywords: acoustic emission, AE, crack classification, RA value, average frequency, concrete structures, non-destructive testing.
Key Topics
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Measurement system and sensors
- AE sensors shall be calibrated in accordance with ISO 12713, ISO 12714 and ISO/TR 13115.
- Broad-band sensors are recommended for parameter analysis; resonance sensors are acceptable when resonance frequencies are higher than 60 kHz in concrete.
- Amplifier internal noise should be low (recommended < 20 µV as peak voltage converted by input voltage).
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Parameters for classification
- RA value: rise time divided by peak amplitude (reciprocal of wave gradient).
- Average frequency: counts divided by duration time (Fa).
- The standard uses the ratio of these AE parameters to discriminate tensile-type from other crack types (including shear), exploiting differences in waveform shape and frequency content.
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Environmental noise and channel checks
- Estimate and reduce external noise sources (wind, rain, traffic, solar heating) prior to measurement.
- Apply filters only after determining proper frequency ranges; recommended AE frequency range in concrete spans several kHz to several 100 kHz.
- Sensitivity variation across AE channels should be within ±3 dB and be verified using a standard source.
Applications
- In-situ condition assessment of ageing reinforced concrete elements (bridges, tunnels, piers).
- Monitoring active crack behaviour under service loads to inform repair or strengthening decisions.
- Integration into structural health monitoring programs to detect transitions in cracking mechanisms (tensile → shear) that may precede deterioration.
Practical workflow highlights:
- Calibrate sensors and verify channel sensitivity.
- Estimate attenuation and noise; position sensors to cover target area.
- Record AE events and compute RA and average frequency for classification.
- Produce a test report documenting devices, locations, pre/post system checks and analytical results.
Related Standards
- ISO 12713 - Primary calibration of transducers
- ISO 12714 - Secondary calibration of AE sensors
- ISO 12716 - AE vocabulary
- ISO/TR 13115 - Reciprocity technique for absolute calibration
- ISO 16836 - Measurement method for AE signals in concrete
This standard is practical for NDT practitioners and engineers who need a standardized AE-based method to classify active cracks and support evidence-based maintenance strategies for concrete structures.