Artificial rockfill placement optimization in rock-filled concrete with massive solid waste

Artificial rockfill (AR) instead of natural rockfill can be used in rock-filled concrete (RFC) to increase the utilization ratio of solid waste. However, research on the placement style of ARs in RFC is still lacking. Artificial rockfill ratio (ARR) and exposed surface ratio (ESR) are taken into account when designing the placement style of ARs. The placement style with the row and column alignment is recommended for single-layer AR placement. The ARR and ESR of ARs with various sizes as influenced by placement styles without/with cushion blocks are compared. The ARR of the two styles both increases as rockfill size increases. The ARR of RFC without cushion blocks is greater than that of cushion blocks for each rockfill size. The ESR of RFC without cushion blocks decreases as rockfill size increases, whereas the ESR of RFC with cushion blocks increases. Placement style with cushion blocks is highly recommended when the particle size of ARs exceeds 300 mm. ARs with solid waste produced with the pressure forming method and self-compacting concrete (SCC) designed using the paste rheological threshold theory are used to produce scaled solid waste RFC specimens. Cracks tend to appear at the interfaces of the ARs and the SCC due to insufficient bonding force. Furthermore, wide cracks appear near the outer layer of the specimen's side wall. The ARR approaches 53.6% by ignoring the formwork sidewall effect and results in a higher solid waste content of 70.2%.