We inspect and monitor the integrity of Buildings, bridges, and tunnels for crack, corrosion rebars and cables, voids, delamination water penetration and other conditions that impair reliability and safety.
Structures Fail without Warning!
Several number of structures fail every year without noticeable warning from design errors, undetected or misevaluated flaws, low quality of construction materials, and other reasons. Precise, dependable assessment and monitoring of a structures’ condition is critical for curtailing the risk of a catastrophic failure.
Different techniques have been developed and used in the decades for non-destructive assessment of metal and reinforced concrete structures. Among these techniques, acoustic emission technology is unique. Not only it detects flaws in metal and concrete but also used for on-line, real time monitoring of the structural integrity under real operational conditions, evaluation of operational risk factors and detecting the causes of flaw origination and development.
Since the 1970s acoustic emission technology has been widely applied for inspection of civil infrastructure over the world and has a proven experience in assessment of:
• Metal and reinforced concrete bridges.
• Industrial and civil buildings.
• Concrete structures after fire, earthquakes and other trauma events.
• Nuclear containment and structures subjected to radiation.
• Landslide activity.
Diagnostic Acoustic Emission Technology for Inspection of Infrastructure
Diagnostic Acoustic Emission is an advanced AE method that was developed since 1970s specifically for assessment of different civil and industrial structures. Development of DAE technology included a wide scale research of acoustic emission characteristics of typical fracture processes developing in different metal and concrete components. A huge number of tests were performed on construction materials with diverse kinds of flaws. Several kilometres of bridges, tunnels, and many buildings were examined before the DAE was developed into a mature and experienced proven technology.
Today, Diagnostic Acoustic Emission has the capability required to answer on the following practical questions:
1. Are the structure and it components stable?
2. Are there flaws in the inspected structure and where?
3. What types of flaws are developing: cracks in concrete and metal, corrosion of reinforcement, fatigue, etc.?
4. How actively these flaws develop?
5. Are these flaws sensitive to load changes?
6. Is the structure overloaded?
7. Is there reduction in cable pre-stressing?
8. Is the concrete quality low?
9. Was the repair effective and has the propagation of flaws stopped?
10. Is there a change in the condition of a structure since the last inspection?
Diagnostic Acoustic Emission vs. Alternatives
Several non-destructive testing methods of metal and reinforced concrete structures were developed in recent decades including radiography, ground penetrating radar, ultrasonic, thermography and others. Each of these methods have several advantages and can detect various types of structural flaws. However, unlike Diagnostic Acoustic Emission, these methods are applied locally, in statistical locations, cannot be used to monitor flaw development or evaluate causes of flaw origination and propagation. Also, once alternative methods detect a flaw, there will always be a question if this flaw is actively developing and how severe it is. DAE can provide an answer on both questions and is used for evaluation of overall structural stability.
Some Unique Advantages of DAE
• Examination of 100% of the structure.
• Detection and assessment of flaws in steel and concrete without limitation of flaw orientation, component thickness or material.
• Evaluation of the flaw propagation rate.
• Differentiating between developing and non-developing flaws.
• Quantitative long-term monitoring of flaws.
• Continuous 24/7 monitoring capabilities.
• Detection of overstressed and non-uniformly loaded components.
• Detection of components with low quality concrete and reduction in pressed levels.
• Evaluation of overall structural stability.
• Evaluation of a repairs effectiveness.
• Examinations performed without traffic interruption.
Acoustic emission method has been used by our specialists for inspection of over 100 kilometres of bridges and tunnels. Many buildings after trauma such as fire, earthquakes and landslides were assessed and monitored using this technology. Results of research and practical inspections were published in many scientific and technical papers. Several patents were issued on unique methodologies for infrastructure assessment.
Acoustic Emission Standardization
Acoustic Emission one of the standard non-destructive test methods with several dozens of standards, procedures and test methods issued by various international organizations such as ASTM, ASME, ISO, EN, GOST, NDIS, RILEM and others.
Here some of the relevant standards, codes and documents:
1. NDIS 2421 (2000), Recommended Practice for In-Situ Monitoring of Concrete Structures by Acoustic Emission, Japanese Society for Non-Destructive Inspection.
2. JCMS-III B5706 (2003) Monitoring method for active cracks in concrete by acoustic emission, Federation of Construction Materials Industries, Japan.
3. Recommendation of RILEM TC 212-ACD: Acoustic emission and related NDE techniques for crack detection and damage evaluation in concrete. Test method for classification of active cracks in concrete structures by acoustic emission, 2010.
4. Recommendation of RILEM TC 212-ACD: Acoustic emission and related NDE techniques for crack detection and damage evaluation in concrete. Test method for damage qualification of reinforced concrete beams by acoustic emission, 2010.
5. Recommendation of RILEM TC 212-ACD: Acoustic emission and related NDE techniques for crack detection and damage evaluation in concrete. Measurement method for acoustic emission signals in concrete, 2010.
6. GOST (1991) Concrete. Acoustic Emission method for strength characteristics determination, State Committee on Construction, USSR.
7. European Norms (2009) EN1330-9 non-destructive testing-terminology-part 9: terms used in AE testing.
8. EN 13554 Non-destructive testing-acoustic emission-general principles.
9. ASTM E569, Standard Practice for Acoustic Emission Monitoring of Structures during Controlled Stimulation.
10. ASTM E1316, Standard definitions of terms relating to AE.
11. ASTM E650, Standard guide for mounting piezoelectric AE sensors.
12. ASTM E750, Standard practice for characterizing AE instrumentation