Production of a low-carbon and economical high-strength artificial aggregate from gold tailings for the preparation of lightweight aggregate concrete

Abstract

This study prepared a low-carbon and economical high-strength artificial aggregates (HSAs) using sulfur-aluminum-ferric cementitious materials (SAF), fluorine gypsum (FG), and gold tailings (GT). Furthermore, HSAs were used to prepare concrete by replacing gravel and sand. The results show that at 80% GT, 17% SAF, and 3% FG, HSA has a high cylinder compressive strength of up to 12.57 MPa, a loose bulk density of less than 1200 kg/m³, a 1h water absorption of 8.35% and a specific strength of 10.48 MPa cm³/g, which are much better than the standard requirements for high-strength artificial aggregates. The main hydration products of HSAs were AFt, AH₃, and C-S-H, where AFt is the skeleton, the AH₃, and C-S-H are the gels, and the un-hydrated particles are the filler, which jointly build up the dense structure of the HSAs. Furthermore, the heavy metal leaching, chloride ion content, and radioactivity of the HSAs meet the standard requirements, which can be considered harmless to the environment. HSAs are prepared from all-solid waste and can consume more than 80% of GT. The CO₂ emission and cost of HSAs were 0.056–0.08 kgCO₂/kg and 39.97–57.1 Yuan/t. Finally, a lightweight aggregate concrete (LWAC) with superior workability, dense structure, and strength class of LC50 was prepared using HSAs.