氟化钙对重构钢渣胶凝活性和体积安定性的影响

Effect of Calcium Fluoride on Slag Cementitious Activity and Volume Stability

针对钢渣作为胶凝材料时存在胶凝活性低、体积安定性差等问题,采用向钢渣中添加不同比例氟化钙(CaF2)的方法来提高重构钢渣的胶凝活性和体积安定性。研究表明,随着CaF2掺量的增加,重构钢渣的胶凝活性指数呈现不断上升的趋势,在CaF2的掺量为5%下,重构钢渣的胶凝活性指数达到120%左右;同时通过EDTA化学滴定发现游离氧化钙(f-CaO)和游离氧化镁(f-MgO)含量均不断下降,最终分别下降到0.09%、0.19%;通过XRD和SEM分析发现,随着CaF2掺量的增加,硅酸二钙(C2S)的衍射峰逐渐减弱,硅酸三钙(C3S)的衍射峰逐渐增强;当CaF2掺量为1%现了铁铝酸四钙(C4AF)、铝酸三钙(C3A)的衍射峰,但C3A的衍射峰较弱。分析原因表明:矿化剂(CaF2)的加入可以促进中间相氟硅酸三钙(3C3S-CaF2)和氟硅酸二钙(2C2S-CaF2)的生成,降低重构钢渣的熔点,增加反应的液相量,降低重构钢渣的粘度,同时CaF2还可提高CaO、SiO2和MgO的反应活性,降低熔渣中f-CaO和f-MgO,促使C3S和C2S顺利生成。

The cementitious activity and the volume stability of reconstruction steel slag were improved by adding different proportion of calcium fluoride(CaF2).The cementitious activity index of the reconstructed steel slag showed a rising trend with the increase of CaF2 content.It wass 120% when the amount of CaF2 was 5%.At the same time,it was found out that the content of free calcium oxide(f-CaO)and free magnesium oxide(f-MgO)decreased continuously by means of EDTA chemical titration,and there dropped to 0.09 % and 0.19 % eventually.XRD and SEM observations showed that with the increase of CaF2 content,the diffraction peak of C2S decreased gradually,and the diffraction peak of C3S increased gradually.The diffraction peaks of C4AF and C3A were observed when the content of CaF2 was 1%.The results indicated that the addition of mineralizer(CaF2)can promote the formation of 3 C3S-CaF2 and 2 C2S-CaF2 in the intermediate phase,in favor of reducing melting point of molten slag,increasing the liquid amount of reaction,reducing the viscosity of reconstructed steel slag,and promoting the formation of C3S and C2S.At the same time,CaF2 increased the reactivity of CaO,SiO2 and MgO,and reduced the content of f-CaO and f-MgO in slag,and promoted the formation of C3S and C2S.