废弃铜矿渣在复合胶凝材料水化硬化过程中的作用机理及长期性能

As a new potential supplementary cementitious materials, waste copper slag not only can improve the properties of concrete and reduce the cost, but also has important ecological and environmental benefits. Copper slag has some unique characteristics, which leads to the change in hydration and hardening mechanisms of composite cementitious materials, however, the effect mechanisms of copper slag, the hydration kinetic mechanism of composite cementitious system and its long-term service are not known clearly. Therefore, in this project, the formation and changing of hydration products and microstructure of copper slag-Portland cement composite system at different conditions will be investigated, and then the hydration properties of copper slag and its effect on hydration of the system will be confirmed; based on the hydration rate of composite cementitious material, the reaction rate and degree of copper slag at different conditions, the hydration and hardening process will be determined, and the prediction model of hydration degree and hydration kinetic equation of composite system will be established, which will reveal the macroscopic and microscopic mechanism of the chemical reaction of cementitious system and the effect mechanisms of copper slag at various hydration periods; and establish long-term service life prediction model of copper slag concrete materials based on long-term service properties.Through this studies, the understanding of effect mechanism of copper slag will be deepened, which will not only be beneficial to recycle waste glass efficiently, but also can provide the scientific basis for its optimum application in concrete.

废弃铜矿渣作为一种新型潜在辅助胶凝材料，既能改善混凝土性能、降低成本，又具有重要的生态环境效益。由于铜矿渣具有某些独特的材料性质，导致复合胶凝材料的水化硬化机制发生改变，而当前对铜矿渣的作用机理、复合胶凝体系的水化动力学机制及长期服役性能尚不明确。为此，本项目将研究不同条件下铜矿渣-硅酸盐水泥复合胶凝体系的水化产物和浆体微结构的形成与演化，明确铜矿渣的水化特性及其对胶凝体系水化的影响；依据不同条件下复合胶凝材料的水化速率、铜矿渣的反应速率和程度，确定水化硬化进程，构建胶凝体系水化程度的预测模型及水化动力学方程，揭示胶凝体系化学反应的宏观和微观机理以及铜矿渣在不同水化阶段的作用机制；铜矿渣混凝土的长期服役性能。通过本项目研究，深化对铜矿渣作用机理的认识，对不仅有利于废弃铜矿渣的高效回收利用，而且为其在混凝土中的合理应用提供科学依据。

为探究铜矿渣这一新型辅助胶凝材料在硅酸盐水泥环境下的水化特性和水化硬化作用机理，通过一系列实验研究和理论分析，较为系统地研究铜矿渣在复合胶凝材料水化硬化过程中的作用机理，取得如下成果：1、探究铜渣粉粒度分布，铜渣粉掺量对复合复合胶凝材料基本性能的影响，结果表明：铜矿渣粉磨各特征粒径筛余符合粉磨动力学方程，粉磨过程中存在粗颗粒易磨，细颗粒难磨现象，铜渣粉颗粒的粒径分布较好地服从RRB分布模型。铜渣粉的掺入会延长水泥凝结时间。铜渣粉掺量为0~30%，水泥凝结时间随着铜渣粉掺量的增加小幅度增长。铜渣粉掺量为30%~50%，凝结时间随着铜渣粉掺量的增加大幅度增长。掺加30%的铜渣粉可以显著改善水泥砂浆的初始流动度。2、将不同细度及掺量铜渣粉掺入复合胶凝体系，研究其对早期水化性能的影响，结果表明：铜渣粉推迟了复合胶凝体系的诱导期结束时间、加速期开始时间及第二放热峰出现时间，降低了复合胶凝体系水化放热量及水化速率。水化12h后，铜渣粉活性逐渐被激发，水化速率加快。由Kstulovic-Dabic水化动力学模型计算得到的复合胶凝体系水化反应速率曲线能较好地分段模拟由量热试验得到的水化速率曲线。掺入铜渣粉会降低复合胶凝体系的抗压强度和抗折强度，铜渣粉-水泥复合胶凝体系的水化产物为氢氧化钙、碳酸钙、硅酸铝钙等。随着龄期增长，水化程度会加深。3d龄期时铜矿渣粉对复合胶凝体系有一定的填充作用，然而体系水化产物较少，其孔隙孔径相对纯水泥较大；28d龄期时随水化程度加深，体系中较多水化产物附着在铜矿渣颗粒表面产生，改善孔隙结构。3、物理-化学活化及耐久性研究表明：Ca(OH)2对铜渣粉水泥体系的激发效果较优，且随着龄期延长效果更明显。水化产物中Ca(OH)2的特征主峰强度随着碳化龄期的增长而减弱，CaCO3与水化碳铝酸钙的特征峰强度随着碳化龄期的增长而增长，说明碳化程度随着龄期的增长而增长。项目研究成果深化了对铜矿渣的认识，为其在水泥基材料中的合理应用提供了技术支撑，具有广阔的应用前景。