Workability and mechanical properties of GGBS-RFBP-FA ternary composite geopolymer concrete with recycled aggregates containing recycled fireclay brick aggregates

Abstract

With urbanization developing, various construction and demolition wastes (CDWs) have emerged, causing environmental and social issues. Green concrete materials, such as recycled aggregates concrete (RAC) and alkali-activated cementitious materials, propose for their environmentally friendly construction. In this study, the ground granulated blast furnace slag (GGBS), recycled fireclay brick powder (RFBP), and fly ash (FA) ternary composite geopolymer concrete with recycled aggregates (GRAC) containing recycled fireclay brick aggregates (RFBA) proposed at first. Then, this study investigated the fresh and hardened properties of this concrete. The experimental variables included the two types of ternary composite geopolymer concrete with recycled fireclay brick aggregates (GRA-RFBAC) mix ratios, five replacement ratios of recycled coarse aggregate, and four replacement ratios of RFBP. The workability and mechanical properties of GRA-RFBAC were studied, respectively. Moreover, the micro-structures and hydration mechanisms of GRA-RFBAC were also studied. The results showed the feasibility of applying RFBP and recycled aggregates containing recycled fireclay brick aggregates (RA-RFBA) in geopolymer concrete, i.e. GRA-RFBAC exhibited good workability and mechanical properties. The addition of RFBP could improve the workability of GRA-RFBAC. GRA-RFBAC with 10% RFBP replacement ratio of was found to have the best mechanical properties. The addition of RA-RFBA has a detrimental effect on both the workability and mechanical properties of the GRA-RFBAC. The stress-strain relationship model of GRA-RFBAC was give and the stress-strain curves of GRA-RFBAC were similar to those of Ordinary Portland cement concrete with recycled aggregates.