矿渣-硅灰协同强化钢渣水化反应机理

 强化钢渣水化过程、激发钢渣胶凝活性对提高钢渣资源利用率具有重要意义。选取矿渣、硅灰作为复合激发剂,采用正交试验设计方法,研究钢渣粒度、矿渣与硅灰添加量对钢渣胶凝活性的影响,并针对钢渣胶凝试块3 d、28 d水化产物进行表征分析以揭示矿渣、硅灰协同强化钢渣水化的机理。正交试验结果表明,硅灰由于其高反应活性能够有效促进钢渣3 d龄期的水化,而矿渣中玻璃相的潜在活性使其对钢渣28 d龄期的水化影响更加显著,当硅灰添加量为2%、矿渣添加量为15%时,钢渣的3 d、28 d胶凝活性分别提高18.34%、28.26%;XRD、TG-DTA和SEM分析结果表明,硅灰的晶种效应、火山灰效应和微集料填充效应与矿渣中活性相对较高的铝氧四面体在钢渣高碱性的液相体系中能够协同强化水化反应,使复合胶凝体系中生成更多的C-S-H凝胶和AFt晶体,C-S-H凝胶紧密包裹AFt晶体,两者交错生长形成复杂密实的网络结构,从而提高胶凝材料的力学性能,达到激发钢渣胶凝活性的目的。将钢渣、矿渣、硅灰复合掺合料应用到混凝土中,结果表明,当复合掺合料替代水泥20%时混凝土力学性能和抗碳化性能均得到最大限度提升,其中3 d、28 d力学性能相比纯水泥混凝土分别提高31.53%、25.88%,3 d、28 d抗碳化性能相比纯水泥混凝土分别提高18.75%、24.11%。

Activation mechanisms of silica fume and blast furnace slag on steel slag hydrated gelling systems

It is of great significance to strengthen the hydration process of steel slag and stimulate the cementitious activity of steel slag for improving the utilization rate of steel slag resources. In order to study the influence of the addition of blast furnace slag and silica fume, also the particle size of steel slag on improving the hydration process, the orthogonal experimental method was adopted, and the hydration products of 3 d and 28 d were characterized to reveal the activation mechanisms of silica fume and blast furnace slag on steel slag hydrated gelling systems. The orthogonal test results show that the effect of silica fume on the early 3 d hydration of steel slag is more significant, while the impact of blast furnace slag on the 28 d later hydration is more significant. when the addition of silica fume is 2%, the addition of blast furnace slag is 15%, the compression strength of steel slag at 3 d, 28 d can increase by 18.34%, 28.26%, respectively. The results of XRD, TG-DTA and SEM showed that the seeding effect, volcanic effect and the micro-assembly effect of silica fume and the relatively high activity aluminum oxyphae in the blast furnace slag can synergistically strengthen the hydration reaction in the high alkaline liquid phase system of steel slag, generating more C-S-H gel and AFt crystals. C-S-H gel is tightly wrapped in AFt crystals, and both interlaced growth form complex and compact network structures, thus improving the mechanical properties of steel slag materials and achieving the purpose of stimulating the cementitious activity of steel slag. Apply steel slag, slag, silica fume composite blend into the concrete, and the results show that when the cement is replaced by 20%, the concrete mechanical properties and anti-carbonation properties are maximized, of which 3 d, 28 d mechanical properties compared with the pure cement concrete increased by 31.53%, 25.88%, and the anti-carbonation properties compared to pure cement concrete increased by 18.75%, 24.11%, respectively.