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Dissolution and Early Hydration Interaction of C3A-C4AF Polyphase in Water and Aqueous Sulfate Solutions
Shaoxiong Ye1, Pan Feng2,3
1College of Civil Engineering, Huaqiao University, Xiamen 361021, China.
Abstract:
The concurrent dissolution and early hydration of tricalcium aluminate (C3A) and tetracalcium aluminoferrite (C4AF) critically govern early-stage reaction dynamics in Portland cement systems. However, their mutual kinetic interactions during reaction, particularly sulfate-dependent modulation mechanisms, remain poorly understood. Using in-situ digital holographic microscopy (DHM), this study resolved their interaction mechanisms during co-dissolution in aqueous and sulfate-bearing environments. Results reveal asymmetric modulation: while C4AF's dissolution exhibited limited sensitivity to C3A's presence, C3A's kinetics were profoundly altered by C4AF through sulfate-concentration-dependent pathways, which originated from two competing C4AF-mediated mechanisms: (1) suppression via common-ion effects, and (2) acceleration through competitive sulfate species adsorption. These mechanistic insights would provide a roadmap for optimizing cementitious materials through optimized reaction pathways.
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