凝灰岩粉-中热水泥复合胶凝材料水化动力学特性研究

Investigation of hydration kinetic procession of tuff powder-medium heat Portland cement complex binder

天然火山灰质凝灰岩有作为混凝土掺合料应用于西部地区水电工程建设的前景。采用等温微量热技术和Krstulovic-Dabic模型,研究了凝灰岩粉-中热水泥复合胶凝体系的水化放热特性和动力学过程。结果表明:凝灰岩粉能够减少复合胶凝材料的水化热,降低水化放热峰的峰值速率,并延缓水化放热峰的出现时间;Krstulovic-Dabic模型可较好的表征凝灰岩粉掺量不超过30%、比表面积不超过800 m^(2)/kg的复合胶凝材料水化过程;复合胶凝材料水化过程包含3个阶段(结晶成核(NG)、相边界反应(I)和扩散(D))。但各阶段的水化速率随凝灰岩粉掺量的增加而降低;随凝灰岩粉比表面积的增加而增大。同时,提高凝灰岩粉掺量、增大凝灰岩粉比表面积可使复合胶凝材料水化有从NG→I→D向NG→D转变的趋势。

Natural pozzolanic material of tuff powder has prospect to be employed as concrete mineral admixture in hydraulic structure construction in western region.It focuses on the heat releasing behavior and hydration kinetic procession of tuff powder-medium heat Portland cement complex binder,using isothermal calorimeter and Krstulovic-Dabic model.Experimental results reveal that tuff powder is beneficial to reduce the hydration heat of complex binder,postpone the appearance time of hydration heat releasing rate peak,and also bring its value.Krstulovic-Dabic model has a good fitting effect to complex binder with a dosage of tuff powder less than 30%,and specific surface area no more than 800 m^(2)/kg.Hydration kinetic procession of complex binder includes nuclear generation(NG)stage,interaction at phase boundary(I)stage and diffusion(D)stage.With the increase of tuff powder content or specific surface area of tuff powder,hydration kinetic procession of complex binder has trend to convert from NG-I→D to NGD.