Development of cold-bond artificial aggregate with excavated soil and alkali-activated slag

Abstract

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.