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目的研究矿物外加剂对氯氧镁水泥(简称镁水泥)强度和耐水性的影响,以解决镁水泥耐水性差、浸水后强度严重损失的问题.方法以粉煤灰、硅灰和铁尾矿为矿物外加剂,利用SEM和XRD观察分析改性后的镁水泥的微观结构和相组成;运用单纯形重心混料设计分析矿物外加剂复掺对镁水泥抗压强度和软化系数的影响;通过回归模型分析矿物外加剂对MgO-MgCl_2-H_2O三元体系抗压强度和软化系数影响的显著性.结果随着粉煤灰掺量的增加,镁水泥的抗压强度逐渐降低,软化系数逐渐提高;随着硅灰掺量的增加,镁水泥抗压强度逐渐降低,软化系数先升高后降低,当硅灰掺量为15%时,软化系数为0.85;随着铁尾矿掺量的增加,镁水泥抗压强度基本保持不变,软化系数降低;当m(粉煤灰)∶m(硅灰)=0.51∶0.49时,镁水泥抗压强度为39.99 MPa,软化系数为0.73.结论矿物外加剂能有效地改善镁水泥的耐水性,提高软化系数;矿物外加剂对镁水泥的改性机理基本相同;混料设计能够有效的分析复掺条件下各组分对镁水泥性能的影响.
Objective To study the effect of mineral admixture on strength and water resistance of magnesium oxychloride cement (referred to as magnesium cement) in order to solve the problem of poor water resistance of magnesium cement and serious loss of strength after immersion in water.METHODS Using fly ash, silica fume and iron tailings as Mineral admixture, the microstructure and the phase composition of the modified magnesium cement were observed and analyzed by SEM and XRD; the influence of the mineral admixture on the compressive strength and softening coefficient of the magnesium cement was designed and analyzed by using the simplex centroid mixture; Model was used to analyze the significant effect of mineral admixtures on the compressive strength and softening coefficient of MgO-MgCl_2-H_2O ternary system.Results With the increase of fly ash content, the compressive strength of magnesium cement gradually decreased and the softening coefficient gradually increased. With the increase of silica fume content, the compressive strength of magnesium cement gradually decreases, the softening coefficient first increases and then decreases, and when the silica fume content is 15%, the softening coefficient is 0.85. With the increase of iron tailings content, The compressive strength of magnesium cement remained unchanged and the softening coefficient decreased. When m (fly ash): m (silica fume) = 0.51: 0.49, compressive strength of magnesium cement was 39.99 MPa and softening coefficient was 0.73. Agent can effectively improve the water resistance of magnesium cement Improved softening coefficient; mineral admixtures substantially identical to a modified mechanism magnesia cement; Mixture designed to effectively analyze the influence of the components under conditions Admixed magnesium cement properties.