Influence of mechanically activated LC3 materials on the structural integrity and hydration phases stability of MPC mortar in water environments

Abstract

This study investigates the stability of physico-mechanical properties and hydration reaction products of MPC composites blending the mechanically activated raw materials of LC3 with a focus on enhancing durability in static and flowing wet environments. The LC3 materials were added as the partial replacement of MPC to refine microstructural properties, improve water resistance, and strengthen long-term mass stability in water. It was shown that blend of LC3 effectively reduced the peak hydration temperature from 87.6 °C to 62.7 °C and prolonged the final hardening periods from 9.52 min to 18.48 min, yielding improved workability. The optimized formulation of magnesium phosphate cement mortar having 25% LC3 achieved superior CS (> 80 MPa at 90d) and a SAI of 109%, confirming the occurrence of synergistic hydrations between the LC3 and MPC ingredients. The WRC ranged from 0.9-0.95 and minimal ML < 5% at 90d under both static and flowing water curing demonstrated the composite material’s high chemical stability. Additionally, microstructural analyses using XRD, SEM, BSE–EDS, Raman spectroscopy, and MIP revealed the formation of stable secondary phases C-S-H, C-A-S-H, AFt, and Mg-Si-O gels with increased crystallinity around 73% and reduced micro porosity nearby 5.1%. The united pozzolanic and filler effects of LC3 components evidently improved matrix densification and water resistance. This research establishes that LC3 as an effective and sustainable modifier for producing high-strength, water-resistant MPC composites suitable for both dry weather and humid-region applications.