钢渣-赤泥-水泥基复合砂浆的水化硬化特性

Hydration Hardening Characteristics of Steel Slag-Red Mud-Cement Based Composite Mortar

为探明二元固废间的协同胶凝作用,本文研究了不同配合比条件下钢渣-赤泥-水泥基复合砂浆的力学性能,并采用水化热、XRD、TG-DTG、SEM等手段来表征复合砂浆的水化特征及微观形貌。研究结果表明:与纯水泥组相比,单掺30%(以下均为质量分数)钢渣会抑制浆体的水化反应,从而降低砂浆的力学性能,而在单掺30%钢渣的基础上复掺适量的赤泥可以有效降低钢渣对砂浆力学性能的负面影响。其中,当钢渣掺量为15%、赤泥掺量为15%时,复合砂浆的28 d抗折强度和28 d抗压强度均最高,分别为6.8和39.8 MPa,与单掺30%钢渣组相比,复合砂浆的28 d抗折强度和28 d抗压强度分别提高了11.5%和20.6%,这主要是因为掺入的赤泥不仅起到物理填充作用,而且为钢渣的水化反应提供了良好的碱性环境,促进钢渣参与水化反应,生成更多的钙矾石和水化硅酸钙凝胶,改善砂浆的微观结构。

In order to investigate synergistic cementing effect between binary solid waste,the mechanical properties of the steel slag-red mud-cement based composite mortar were investigated under different ratio conditions,and the hydration characteristics and microscopic morphology of composite mortar were characterized by hydration heat,XRD,TG-DTG,SEM,etc.The study results show that compared with pure cement group,single addition 30%(the following are mass fractions)steel slag inhibits hydration reaction of slurry,and reduces mechanical properties of mortar.On the basis of adding 30%steel slag alone,adding an appropriate amount of red mud can effectively reduce the negative impact of steel slag on the mechanical properties of mortar.The 28 d flexural strength and 28 d compressive strength of composite mortar are the highest when the steel slag is mixed with 15%and the red mud is mixed with 15%,which are 6.8 and 39.8 MPa,respectively.Compared with the group with single addition 30%steel slag,the 28 d flexural strength and 28 d compressive strength increase by 11.5%and 20.6%,respectively,mainly because the red mud not only plays the role of physical filling,but also provides the physical filling for hydration reaction of steel slag.The hydration reaction of steel slag provides a good alkaline environment,which promotes participation of steel slag in the hydration reaction and generates more calcium alumina and hydrated calcium silicate gel to improve the microstructure of mortar.