Evaluation of Korean recycled aggregates as backfilling underground power system considering particle breakage effect

Attempts have been made to address the strict regulations on eco-friendly construction and recycle aggregate resources, encouraging researchers to consider the utilization of recycled aggregates for the backfilling of underground power systems. It is essential to recognize the physical and thermal characteristics of domestic recycled aggregates for use as backfill materials for underground power conduits in Korea. Herein, the thermal properties of concrete-based recycled aggregates with different grain-size distributions are evaluated, and the particle breakage effect of recycled aggregates is identified through the compaction tests. The thermal properties of the recycled aggregates and the river sand were measured using a transient hot wire method after a standard compaction test. The particle breakage effect was also investigated during the standard compaction test. The thermal resistivities of the recycled aggregates and the river sand showed a similar trend, which were decreased with an increase in the water content at the same dry unit weight. In addition, particle breakage during compaction led to an enhanced compaction effect, reducing the thermal resistivity and increasing the fine particle content. This study shows that the recycled aggregates can be promising backfill materials that substitute natural aggregates when backfilling underground power conduits.