In Japan, the treatment of waste concrete scraps has been one of the environmental issues. Therefore, new application using pulsed power discharge has been developed as the recycling method of the coarse aggregates from the waste concrete scraps. In the work, the dependences of the quality of the recycled coarse aggregate by the repetitive pulsed discharge treatments on the consumption energy were investigated. As the results, it was clear that the quality of the recycled coarse aggregate could be controlled by the number of discharge treatments. The recycled coarse aggregate, which satisfied class H under the regulations of Japan Industrial Standard (JIS A5005 and JIS A5021), was produced with the smallest consumption energy when the discharged energy from 0.02 µF of capacitor charged up to 400 kV applied to the waste concrete scraps during single discharge treatment.

In Japan, the most of waste concrete scraps have been reused as roadbed materials and the recycling ratio of waste concrete scraps has been kept over 95 % from 2000. However, it is expected that the demands of waste concrete scraps as roadbed materials would decrease even though the waste concrete scraps increase with the pulling down buildings in next decade. These facts mean that the recycling of waste concrete scraps would be in the negative situation. Therefore, the development of new recycling technology of waste concrete scraps is paramount importance in Japan. In this work, the pulsed power discharges inside of waste concrete scraps immersed in water were used to reproduce the coarse aggregate. In the experiments, the Marx generator, which storages the energy of 6.4 kJ/Pulse, was used as pulsed power source and the point to hemisphere mesh electrode was immersed in water. The pulsed voltages with 400 kV of peak voltage were applied to the concrete scraps placed on hemisphere mesh and the reproduced coarse aggregates were evaluated after the repetitive discharge treatment. From the experimental results, it is found that the coarse aggregates reproduced by 40~60 pulsed discharge treatments have the enough qualities of the bone-dry density and the water absorption rate to satisfy JIS (Japan Industrial Standard) regulation (A 5005). In addition, the concretes consisted of the reproduced coarse aggregate also have the enough compressed strength and Young's module to utilize as the construction material.

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