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This study investigates the feasibility of utilising high-volume ES along with alkali-activated slag to manufacture cold-bond artificial aggregates. The effects of slag content, alkali dosage, and silicate modulus of the alkaline activator on the properties of the alkali-activated aggregate (AAA) were evaluated, including aggregate size distribution, apparent density, water absorption, and crushing strength. Subsequently, microstructural and statistical analyses were conducted to elucidate the underlying mechanisms. The results indicate that higher GGBS content and alkali dosage significantly enhance the engineering properties of AAA. Specifically, increasing the GGBS content from 10 % to 40 % raises the 28-day crushing strength from 1.71 MPa to 8.98 MPa and reduces the 24-hour water absorption from 15.9 % to 9.5 %. Similarly, increasing the alkali dosage from 4 % to 8 % boosts the 28-day crushing strength of AAA by 26.0 % and reduces the 24-hour water absorption by 25.2 %. The variation in silicate modulus has a marginal impact on the properties of AAA, with an optimal value of 1.0. The improvement in the AAA properties relies heavily on the reaction products and pore structure, showing high correlation coefficients ranging from 81.039 % to 94.306 %. Particularly, pores between 100 and 1000 nm could predominantly affect these properties. Overall, this study presents a novel method for producing eco-friendly AAA by stabilising ES with alkali-activated slag, promoting the high-value utilisation of ES.

Ferritic stainless steel achieves a lower and steady price level due to low nickel content compared to duplex and austenitic stainless steels. Accordingly, the combination of ferritic stainless steel tube and concrete will have better application prospects in corrosive marine environments. However, the structural application of concrete-filled ferritic stainless steel tube (CFFSST) members is still limited due to the absence of performance data and design guidelines. Accordingly, this paper aims to comprehensively investigate the behaviour of eccentrically loaded concrete-filled rectangular ferritic stainless steel tubular (CFRFSST) slender columns using the nonlinear finite element (FE) method, and develop a suitable design method. Two different material models were introduced to simulate corner and flat regions of rectangular ferritic stainless steel tube. Good consistency was found between the simulation and experimental results against the failure mode, ultimate load and moment, and axial load versus mid-height deflection curves for eccentrically loaded CFRFSST slender columns. This is followed by the mechanism analysis and parameter study of the studied CFRFSST columns, which revealed that the longitudinal stress and Mises stress show significant changes perpendicular to the loading line direction, while there is almost no change along the loading line direction. In addition, the initial stiffness and ultimate load increased by increasing the cross-sectional aspect ratio, yield stress and concrete strength, while they decreased as the eccentricity ratio, slenderness ratio and width-to-thickness ratio increased. The outputs of the FE analysis and existing experimental results were used to examine the applicability of current design codes for designing the studied CFRFSST columns. The results demonstrated an unexpected deviation generated in the design predictions. At the end, a new design method for eccentrically loaded CFRFSST slender columns was proposed which achieved better predictive consistency.