Detection and Analysis of Electromagnetic Radiation Emission from Macroscopic Fracturing of Cement-bound-granular Matter

Countries most prone to earthquake damage have been in search of a possible earthquake precursor. This thesis aims to detect and measure the magnetic field component of the Electromagnetic Radiation (EMR) emitted by quasi-brittle materials that undergo macroscopic fracturing. Cement-Bound Granular Material (CBGM) beam composites were prepared by mixing cement, sand and gravel. Fine sawdust was added to form another aggregate component of the CBGM variant. Impact loading was repeatedly performed on the beams to induce fracture until failure. Six Vernier software magnetic field sensors, with sensitivity range of ±6.4x10-3 T and 0.0002 mT precision, were strategically positioned around the beams to detect the magnetic field (MF) component of the EMR emission. Initial calibration was done to minimize noise in the laboratory. The time of impact was determined in the form of collision noise using a sound level meter at fast time setting. CBGM beams consisting of cement, sand and gravel produced magnetic field emissions measuring from 0.58-1.07 μT while the CBGM beams with dispersed fine sawdust emitted 0.55-1.28 μT. Increasing the input energy from the mass of weight drop by 150% resulted to a 10% increase on the mean value measurements of magnetic field emission magnitude.