Hardening performance and mechanism of hydraulic fluorgypsum-based binding material

Hardening, hydration performance and mechanism of the hydraulic fluorgypsum-based binding material were studied in this paper. The fluorgypsum-based binding material were mixed 60% fluorgypsum with other chemical activators contained 1% K
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SO
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, 5% clinker and 35% blast furnace slag. The 28-day compressive strength of the the fluorgypsum-based binding material could reached 41.25MPa, the softening coefficient was 0.936, and the concentration of fluoride reduced to 0.0701 ug/ml‥ Microscopic analyses using XRD, SEM and FTIR revealed that: bar-like ettringite crystals and board-like dihydrate gypsum crystals contacted each other as structural framework. The rest round-flake anhydrite crystals and unreacted CaF
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crystals were embedded by a great deal of network and filamentous C-S-H gel, they sticked and filled in structural framework and formed compacted body. It was main reason that fluorgypsum-based binding material strength improved, water resistance increased and leaching toxicity decreased.