加速碳酸化条件下钢渣块体体积安定性的研究

Study on Soundness of Steel Slag Block under Accelerated Carbonation

通过开展加速碳酸化将钢渣硬化为结构材料的研究,具有利用废渣和CO 2废气的双重意义。针对钢渣碳酸化过程中可能存在的体积安定性问题,测定了不同细度、碳化反应时间对硬化试块空隙率、体积变化及力学强度的影响,利用质量损失计算了碳酸化后空隙率,利用XRD分析了产物的类别,利用SEM观察了硬化产物的显微形貌及生长位置,采用压蒸法对碳酸化后硬化钢渣试块的安定性进行了测试。结果表明了钢渣坯体碳酸化过程会降低块体的空隙率,钢渣在粉磨8 h,碳酸化7 d的条件下,总空隙率仅为16.67%,空隙率降低了10.17%,压蒸后,并未出现裂纹和损坏,体积安定性良好。同时钢渣中C2S、C3S、Ca(OH)2、f-CaO、MgO是易被碳化的矿物,而Ca2(Al,Fe)2O5、FeO矿物难以被碳化。分析指出,钢渣坯体中足够的空隙,以及CaCO3在空隙(非原地)中生长机制是碳酸化钢渣无体积安定性问题的根本原因。

The research on steel slag hardening as a structural material by accelerated carbonation has the significance of using both waste slag and CO 2 waste gas.To solve the soundness problem that may exist in the carbonation process of steel slag,the effects of different fineness and carbonization reaction time on the porosity,volume change and mechanical strength of the hardened block were measured.The void ratio after carbonation was calculated by mass loss.The product was analyzed by XRD.The microstructure and growth position of the hardened product were observed by SEM.The soundness of the hardened steel slag block after carbonation was tested.The results show that the carbonation process of the steel slag body will reduce the porosity of the block.Under the condition of 8 h of grinding and 7 d of carbonation,the total porosity of the slag is only 16.67%,and the void ratio is reduced by 10.17%.There are no cracks and damage autoclave method for soundness and the volume stability is good.In addition,C 2S,C 3S,Ca(OH)2,f-CaO and MgO in the steel slag are easily carbonized,while Ca 2(Al,Fe)2O5 and FeO minerals are difficult to be carbonized.The analysis indicates that the good soundness of the carbonated steel slag block is due to sufficient voids in the steel slag block and the growth mechanism of CaCO3 in the voids(non-in situ).