Development and performance analysis of structural lightweight aggregate self-compacting concrete: A sustainable solution

The use of coarse sintered fly ash aggregates (SFA) in lightweight concrete offers an innovative approach to reducing a dead load of structures while self-compacting concrete (SCC) enhances workability by facilitating effortless pouring and eliminating construction difficulties. Investigating the integration of lightweight aggregate (LWA) in SCC is a growing field of research. Attaining this objective establishes a logical mix design approach for LWA-SCC by optimizing the packing process, efficiently utilizing SFA, and preserving natural building materials, thereby supporting low-carbon, eco-friendly, and sustainable development. This study investigates the impact of incorporating coarse SFA on the fundamental workability (slump flow, T500, L-Box, and V-funnel), mechanical properties (compressive strength, tensile strength, and direct shear), and long-term performance (rapid chloride penetration, capillary absorption, and acid resistance) of LWA-SCC, using different proportions of fly ash (FA) and ground granulated blast furnace slag (GGBS). Seven SCC mixes were designed, including one control SCC mix (CSFA). The other six LWA-SCC mixtures were divided into two groups, Group A and Group B, with partial replacements of FA and GGBS at 30 %, 50 %, and 70 %, respectively. The findings confirmed the suitability of the proposed method, as the developed LWA-SCC mixes exhibited a slump flow ranging from 650 to 750 mm and a compressive strength varying between 27 and 52 N/mm2. FTIR and XRD analyses further validated the formation of hydration products, including C-A-S-H phases. Additionally, the results highlighted that incorporating mineral admixtures in green LWA-SCC mixtures offers substantial environmental benefits.