偏高岭土和硅灰对三元胶凝材料的改性

Modification of ternary cementitious materials blended with metakaolin and silica fume

为了提高水泥基材料中辅助性胶凝材料用量,对比研究偏高岭土(MK)和硅灰(SF)对高粉煤灰(FA)掺量的三元胶凝材料体系抗压强度和微观结构的影响。结果表明:适量MK和SF均能提高FA掺量的三元胶凝材料不同龄期的强度,两者对强度的提高幅度随掺量和浆体龄期的改变而稍有改变;MK和SF均能显著降低三元胶凝材料浆体中Ca(OH)2(CH)的含量、优化浆体孔结构,但两者反应形成的产物有明显不同。MK和SF的物理填充、火山灰效应可优化三元胶凝体系浆体的微观结构、改善不同相界面结合。高品质MK可代替SF用于制备高FA含量三元胶凝材料体系。

To increase the amount of supplementary cementitious materials in cement-based materials,ternary cementitious system of fly ash（FA）-metakaolin（MK）-cement（PC） and FA-silica fume（SF）-cement were prepared,and their compressive strengths and microstructures were investigated.The effects of MK and SF on high-volume FA content cementitious system were compared.Results showed that suitable dosage of MK and SF could enhance the compressive strength of high FA volume ternary system,MK and SF had a slightly different effect due to dosage and curing time.MK and SF could reduce the content of Ca（OH）2（CH） and refine pore structure.The hydration reaction products formed the reaction between MK and CH were different from that with SF.MK and SF could improve microstructure and interface in pastes for their filler and pozzolanic effects.The high quality MK had similar or even better effect than that of SF used in high volume FA cementitious system.