Evaluation of chemo-physio-mechanical characteristics of GGBS-MBS-based ready-mix geopolymer under ambient curing condition

Abstract

This research demonstrates the synthesis of GGBS-based ready-mix (one-part) geopolymer (RMG) utilizing MBS as partial replacement to GGBS (10, 20 and 30 % by-mass) in addition to solid-alkaline reagents (NaOH-flakes and Na₂SiO₃ powder) using thermal and mechanical treatments, resulting in the formation of “ready-to-use” geopolymer product, “just-add-water” alike cement. The RMG was characterized by analyzing mineral phases, functional-groups identification followed by surface-morphology and elemental analysis at multiple stages, and engineering properties such as setting-time, flowability, compressive strength and ultrasonic-pulse-velocity were evaluated under ambient curing condition. The results show that GGBS-MBS-based RMG has dense morphology, affirming the development of C-S-H and C(N)-A-S-H gels due to its amorphous nature with some crystalline-phases (SiO₂) which are in-linked to Si-O-Si and Al-O-Si bonds. The dry-mix of GGBS with powdered-Na₂SiO₃ and 4 m molality NaOH (Na₂SiO₃/NaOH=1), pre-heated at 105±5°C for 6 h, followed by 6 h ball-milling with 20 % MBS replacement, achieved the highest 28-day compressive strength of 72.8 MPa, 10 % higher than the referenced mix and had satisfactory UPV results. The RMG not only solves handling problems caused due to concentrated aqueous-alkaline reagents used in two-part geopolymer synthesis but also provides sustainability by utilizing industrial and agricultural waste/by-products, hence reducing Portland cement demand, carbon footprint and waste-disposal issues.