Immobilisation Science Laboratory, Department of Engineering Materials, University of Sheffield Acoustic Emission Testing and Analysis Applied for Materials Used for Immobilisation of Nuclear Wastes L.M. Spasova, M.I. Ojovan and F.G.F. Gibb

IAEA CRP on Cementitious Materials. Bucharest Outline AE project at the ISL Experimental Setup AE signature of corrosion of Al encapsulated in cementitious structures Plans to complete the study AE signature of partial melting and solidification/recrystallisation of natural granite

IAEA CRP on Cementitious Materials. Bucharest At the Beginning Objective of the Project FEASIBILITY of AE method to be applied to materials used for immobilisation of nuclear wastes V. Belov and A. Aloy, “Using AE in quality control of glass and ceramics for radioactive waste immobilization”, Mat. Res. Soc. Symp. Proc., 807, (2004), Al OPC Courtesy of Prof Fergus Gibb 180 days, 20 °C and 95% RH AE project at the ISL

IAEA CRP on Cementitious Materials. Bucharest Non-destructive Testing and Evaluation Visual Electromagnetic Magnetic Vibration Ultrasonic Sonic Acoustic Emission Thermographic Infrared Thermography Radiographic Ultrasonic and Acoustic Tomography Radar Neutron X-Ray Optic Fourier Laser Scattering Coherent Amplified Raman Polarisation Eddy Current Nuclear Magnetic Resonance NDT&E Methods Stress Wave

AE Computer-based Instrument Pre-amplifier PCI-2 AE Data Acquisition Board AE Notebook Controller AE Sensor AE Source AE Wave Pre-trigger Duration Amplitude Rise Time Threshold Counts = 9 Absolute Energy = aJ Counts Acoustic Emission

IAEA CRP on Cementitious Materials. Bucharest Experimental Setup Piezoelectric Transducer Preamplifier Data Acquisition and Processing Data Storage, Visualisation and Control Cement Sample 40 dB Threshold level 5 MSPS Sampling Rate WD → 100 – 1000 kHz 40 dB

IAEA CRP on Cementitious Materials. Bucharest Corrosion of Al in Cements Observation 180 days 7:3 BFS/OPC + Al 90 days OPC Al Hydrogen Gas Release 7:3 BFS/OPC + Al 7 days Radial Cracks Formation and Extension Sources of AE signals OPC 4 years

IAEA CRP on Cementitious Materials. Bucharest AE Monitoring Number of AE Signals BFS/OPC +Al (After mixing) BFS/OPC + Al (180 days) OPC + Al (90 days) OPC + Al (After mixing) 7:3 BFS/OPC + Al 7 days

IAEA CRP on Cementitious Materials. Bucharest AE Signal Characteristics Amplitude OPC + Al (After mixing) BFS/OPC +Al (After mixing) OPC + Al (90 days) BFS/OPC + Al (180 days) 180 days 7:3 BFS/OPC + Al 90 days OPC Al

IAEA CRP on Cementitious Materials. Bucharest AE Signal Characteristics Primary Frequency OPC + Al (After mixing) BFS/OPC +Al (After mixing) OPC 4 years OPC + Al (90 days) BFS/OPC + Al (180 days)

IAEA CRP on Cementitious Materials. Bucharest Signal Processing Cross-correlation Wavelet Transformation where m= 1,2...2N-1 and N is the number of samples where is the centre frequency is a constant calculated as Suzuki, H., Kinjo, T., Hayashi, Y., Takemoto, M. & Ono, K., Appendix by Hayashi, Y., Wavelet Transform of Acoustic Emission Signals, J. Acoustic Emission, 1996, 14(2), 69–84.

IAEA CRP on Cementitious Materials. Bucharest BFS/OPC + Al (180 days)

IAEA CRP on Cementitious Materials. Bucharest BFS/OPC + Al (180 days) Wavelet Transformation Time, µs Frequency Time, µs Frequency Time, µs Frequency

IAEA CRP on Cementitious Materials. Bucharest OPC + Al (90 days) Time, µs Frequency Time, µs Frequency

IAEA CRP on Cementitious Materials. Bucharest Crack Initiation and Propagation C. Grosse, H. Reinhardt and F. Finck, J. Mater. Civil Engineering, 2003, 15 (3), F. A. K. M. Uddin, M. Shigeishi and M. Ohtsu, Meccanica, 2006, 41, Avnon and D. Yankelevsky, Engineering Fracture Mechanics, 1992, 42(6), Crack propagation velocity m/s Crack propagation velocity : Plastic deformation stress wave velocity = 1:2 to 1:3 Plastic deformation stress wave velocity = 20% of elastic wave velocity Shear elastic wave velocity in concrete 2600 – 2800 m/s Plastic deformation wave velocity 520 – 560 m/s Crack propagation velocity ~173 – m/s F. A. K. M. Uddin, K. Numata, J. Shimasaki, M. Shigeishi and M. Ohtsu, Constr. Build. Mater., 2004, 18,

IAEA CRP on Cementitious Materials. Bucharest Cracks in Cementitious Samples Wavelength OPC + Al (90 days) OPC + Al (4 years)

IAEA CRP on Cementitious Materials. Bucharest Additional Experiments Compression and tensile test of the cementitious samples Background Noise Cementitious samples (OPC and 7:3 BFS/OPC) with encapsulated Mg

IAEA CRP on Cementitious Materials. Bucharest Melting and Solidification/ Recrystallisation of Granite Crystal Glass Before After Granite wt%, at 780 ˚C for 334 hours, 0.15 GPa Glass Crystal Granite wt%, at 780 ˚C for 338 hours, 0.15 GPa Crystal Glass Granite Powder Solid Granite

IAEA CRP on Cementitious Materials. Bucharest Experimental Setup Furnace Pressure Vessel

IAEA CRP on Cementitious Materials. Bucharest AE Monitoring Melting of Granite Samples Constant temperature (at 780 °C) heating of granite powder sample Heating of the solid granite sample

IAEA CRP on Cementitious Materials. Bucharest AE signal Characteristics Granite Powder Solid Granite Experiment with a solid quartz sample to be completed

IAEA CRP on Cementitious Materials. Bucharest Conclusions Acknowledgements National Nuclear Laboratory (BNFL, Nexia Solutions) and EPSRC for funding AE technique is feasible to continuously monitor the performance of cement-based materials encapsulating metallic wastes such as aluminium.