高炉矿渣的组成和结构对其在碱性环境中早期水化特性的影响

Effect of Chemical Composition and Structure of Blast Furnace Slag on Its Early hydration Characteristics in Alkaline Environment

以不同组成和结构的高炉矿渣作为研究对象,借助XRD、ICP-MS以及29Si MAS NMR等微观测试手段,探究了高炉矿渣在碱性环境中的离子溶出特性、硅氧四面体聚合状态随水化龄期变化的影响规律。研究表明:高炉矿渣中玻璃体的活性受其化学组成和结晶相含量影响,结晶相及铝氧结构单元的存在和增多降低了玻璃体结构的聚合度;网络改性剂在玻璃体结构中表现为不均匀分布,不同网络形成体结构单元的水解会伴随不同的水化特性;在碱性环境下,高炉矿渣玻璃体结构中硅氧四面体含量较大时,其硅氧结构更易被破坏,溶液中硅离子的浓度较高,溶液pH值维持在较低水平,生成的水化产物中高聚态硅氧四面体较多;高炉矿渣玻璃体结构中铝氧四面体含量较大时,其铝氧结构更易被破坏,溶液中铝离子及钙离子的浓度较高,液相pH值维持在较高水平,生成的水化产物中高聚态硅氧四面体较少。

The composition and structure of blast furnace slag have influence on its early hydration characteristics. In this paper, various blast furnace slag with different chemical composition and structure were studied by means of X-ray diffraction, ICP-MS spectroscopy and 29 Si MAS NMR to research the relationship among glass phase polymerization state with the ion dissolution characteristic in alkaline environment, and the change of silicate tetrahedron polymerization state with hydration age. The results showed that the structure of glass phase was affected by chemical composition and content of crystalline phase in which the existence and increase of crystalline phase and Al-O structure unit could reduce the degree of polymerization. In the glass phase network structure, the network modifier was inhomogeneously distributed among the networks, and the hydrolysis of the different structural units would be accompanied by different hydration characteristics. In alkaline environment, the more Si-O structure units in glass phase, the structure of Si-O was more easily hydrated, resulting in higher concentration of silicon ions in the solution, and more exist of polymeric silicate tetrahedrons in the gel products, and the pH value of environment was obviously decreased. With the more exist of more Al-O structure units, the structure of Al-O was more easily hydrated, resulting in higher concentration of aluminum ion and calcium ion in the environment, which corresponding to only a small amount of highly polymeric Si-O tetrahedron could be distinguished in the gels, and the hydration process could keep at a high pH value.