Effects of compaction parameters on compressive strength of roller-compacted concrete using ground granulated blast-furnace slag

Roller-compacted concrete (RCC) is a zero-slump concrete in which compaction plays a critical role in determining strength and durability. This research investigated the effects of compaction parameters on the compressive strength of RCC incorporating varying contents of ground granulated blast-furnace slag (GGBFS). Different compaction techniques, including the vibrating hammer and Proctor hammer, were evaluated along with the influence of compaction energy levels—low, standard, and high. Compressive strength tests were conducted at 7, 28, and 56 days on RCC specimens compacted using both methods. Results showed that replacing cement with GGBFS reduced compressive strength at 7 days but improved it at 28 and 56 days. Specimens compacted with the vibrating hammer consistently exhibited higher compressive strength than those compacted using the Proctor hammer. Insufficient compaction energy in the Proctor method led to a general reduction in strength across all mixtures. Conversely, increasing compaction energy slightly decreased the strength of Group A mixtures, likely due to aggregate breakage and disruption of optimal packing. In contrast, the Group B mixtures showed improved strength at higher compaction energy, likely because the energy level was sufficient to achieve maximum density. However, when the compaction energy exceeded the optimal level, a decline in strength was observed