Durability of high strength self-compacting concrete with fly ash, coal gangue powder, cement kiln dust, and recycled concrete powder

This research studies the durability of self-compacting concrete (SCC) with fly ash (FA), coal gangue powder (CGP), cement kiln dust (CKD), and recycled concrete powder (RCP) by absolute volume method. The fresh properties of self-compacting concrete (SCC) mixtures were assessed by slump flow, T50 cm slump flow, and V-Funnel flow time. The strength and durability properties were evaluated using a compressive strength test, Freeze-thaw resistance, chloride ion penetration, and carbonation resistance tests. Furthermore, the pore structure of concrete after a 90-day curing period was analyzed using Mercury Intrusion Porosimetry (MIP), which provided valuable information on the distribution and properties of pores inside the material. The results revealed that SCC with FA and CKD performed best with a slump flow of 700 mm. Specimens with FA and RCP have greater compressive strength after 90 days of curing, making them appropriate for high-strength applications. In terms of freeze-thaw resistance, SCC with CGP exhibits the lowest mass loss rate, indicating the best resistance, followed by FA and CKD, with RCP showing the least resistance. FA and CKD have excellent enhancement effects for SCC resistance to chloride ions. Specimens with RCP have the lowest carbonation depth and the best carbonation resistance. The findings suggest that the concrete specimens with fly ash (FA) have the highest total pore area and porosity, with a wide range of pore sizes and a prominent peak in the capillary pore size range, indicating a highly porous structure. This study provides practical advice on how to use SCC in construction and improve material selection and optimization.