Regulating Hydration Heat in Magnesium Phosphate Cement Using Paraffins: Efficacy and Performance Trade-Offs

Le résumé fourni par la source

Magnesium phosphate cement (MPC) holds great potential for rapid repairs, yet its practical application is limited by its intense hydration exotherm. While many existing studies confirm paraffin (PA)’s ability to regulate hydration heat in other cement-based materials, the comparison of hydration heat regulation efficacy among PAs with different phase change temperatures and the accompanying performance trade-offs in MPC systems remain insufficiently explored. This study comprehensively evaluates the effects of three PAs with distinct phase change characteristics (n-C18, n-C20, n-C22) and their contents on the hydration heat regulation and performance of MPC. Direct incorporation of PAs was adopted to assess its practical feasibility, considering construction cost-effectiveness. Investigations were conducted using hydration heat release tests, temperature rise monitoring, DSC, mechanical tests, XRD, and SEM. Results show that all PAs significantly retarded heat release and suppressed temperature rise, with efficacy increasing with phase change temperature; a maximum exothermic peak reduction of 64% was achieved with 4% n-C22. PAs also introduced distinct temperature plateaus near their phase change temperature, further enhancing temperature regulation. As a key trade-off, compressive strength decreased with increasing PA content, but mixtures with n-C18 ≤ 8%, n-C22 ≤ 4%, and n-C20 = 2% still met the standard strength requirement for rapid repair, 3 h compressive strength ≥ 20 MPa. Microstructural analysis reveals that while regulating hydration heat, PA also hindered the hydration product formation and crystallization, underpinning the observed performance trade-offs. This study establishes a clear performance correlation between PAs with different phase change temperatures and MPC, clarifies the intrinsic trade-offs between heat regulation and mechanical properties, and offers actionable guidance for engineering applications—facilitating the development of high-performance PA/MPC composites with controllable heat release for rapid repair scenarios.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.