陶瓷抛光渣对水泥基材料碱集料反应的影响

Effect of Ceramic Polishing Powder on Alkali-Aggregate Reaction of Cement-based Materials

以0%、20%、30%、40%陶瓷抛光渣等量取代水泥制备砂浆试样,矿渣作对比试验,通过膨胀率、强度测定、扫描电子显微镜观察和能谱分析,研究陶瓷抛光渣对水泥基材料碱集料反应的影响规律,揭示矿物掺合料抑制碱集料反应的机理。结果表明：陶瓷抛光渣能有效抑制水泥基材料的碱集料反应膨胀,且其抑制作用比矿渣更显著;两种掺合料使集料与胶凝材料界面区结构更密实,界面宽度更小;抛光渣的合理掺量为20%～30%、矿渣掺量应〉30%。矿物掺合料抑制碱集料反应的机理为界面过渡区中Ca/Si比降低使集料表面碱度降低,降低了近集料区域生成高Na/Si比膨胀性产物的可能性,并且K^＋和Al^3＋在近集料处富集,形成非膨胀性产物。由于体系中Al2O3的存在,使K^＋对碱集料反应的作用低于Na^＋的作用。

The influence of ceramic polishing powder on the alkali-aggregate reaction of cement-based materials was investigated. The mortar specimens were prepared by replacing 0%, 20%, 30%, and 40% of cement with the same amount of ceramic polishing powder. The expansion rate and strength were measured. The inhibition mechanism of the mineral admixture on the alkali-aggregate reaction was analyzed by scanning electron microscopy and energy disperse spectroscopy. The results show that ceramic polishing powder can restrain alkali-aggregate reaction of cement based materials. The inhibition effect on alkali-aggregate reaction of ceramic polishing powder is greater than that of slag. The mortar specimens modified with the two mixtures have a larger density and a smaller porosity, and the width of interracial transition zone is narrower. The optimum content of the ceramic polishing powder is 20%-30% and the content of slag is greater than 30% to inhibit the expansion of alkali-aggregate reaction effectively and achieve the requirements of strength as well. Also, the reduction of Ca/Si ratio in the interracial transition zone can reduce the alkalinity on the surface of aggregate. The possibility of producing expansibility products with a high Na/Si ratio in the aggregate region decreases. The accumulation of K^＋ and Al^3＋ in the aggregates can generate the non-expansive product, which is the mechanism of the mineral admixture inhibition in the alkali-aggregate reaction. In addition, the effect of K^＋ on the alkali-aggregate reaction is weaker than that of Na^＋ due to the existence of Al2O3 in the system.