石灰石粉复合磷酸镁水泥的高温性能及机理

Properties and Mechanisms of Limestone Powder Blended Magnesium Phosphate Cement under High Temperature

摘要:

为扩大磷酸镁水泥（MPC）在高温环境的应用，研究了高温作用后石灰石粉（LP）复合磷酸镁水泥（LP-MPC）的高温性能及机理。结果表明：随着温度的升高，LP-MPC的质量损失率增大，抗压强度呈先下降后平稳的趋势，孔结构特征趋于劣化；当温度低于600 ℃时，LP-MPC主要以MgKPO₄·6H₂O脱水为主，LP对提高MPC的抗压强度有利；当温度高于600 ℃时，CaCO₃高温分解，随着LP掺量的增加，LP-MPC质量损失率增大，抗压强度减小，温度及LP掺量对孔隙结构的劣化影响显著；高温后LP-MPC相同分形区域下的孔隙结构随着温度的升高复杂程度降低，有害孔与多害孔的分形维数与抗压强度的相关性更高。

Abstract:

To expand the application of magnesium phosphate cement（MPC） in high-temperature environments， the properties and mechanisms of limestone powder blended magnesium phosphate cement（LP-MPC） after exposure to high temperature were investigated. The results indicate that as the temperature increases， the mass loss rate of LP-MPC gradually rises， while the compressive strength exhibits an initial decline followed by a stabilization trend， accompanied by a deterioration in pore structure characteristics. Below 600 ℃， dehydration of MgKPO₄·6H₂O dominates in LP-MPC， and LP is beneficial for enhancing the compressive strength of MPC. However， above 600 ℃， CaCO₃ undergoes decomposition at high temperature， leading to an increased mass loss rate and a decrease in compressive strength as LP content increases. Both temperature and LP content significantly affect the deterioration of pore structure. After high temperature exposure， the complexity of pore structure in LP-MPC decreases with rising temperature within the same fractal region， and the fractal dimension of detrimental and highly detrimental pores correlate more closely with compressive strength.