长龄期尾矿/矿渣复合碱激发胶凝材料的典型微观形貌

采用扫描电镜观察了由煅烧铝土矿选尾矿(含约25%粉煤灰)、矿渣制备的复合碱胶凝材料在6年龄期内的微观形貌变化,并研究了6年龄期试样中结晶体沉积、粉煤灰颗粒形态等典型形貌特征.结果表明,该胶凝材料具有常见的多孔凝胶典型形貌,且随着龄期的延长而逐渐致密;6年龄期试样因碳化而明显可见碳酸钙晶体沉积于数百微米的大孔和大颗粒粉煤灰空腔中,并观察到高活性的粉煤灰玻璃微珠因碱侵蚀而形成的壳层、被凝胶包裹的低活性多孔玻璃质粉煤灰颗粒及惰性富铁粉煤灰微珠.

The micro-morphology of the long-term geopolymer synthesized from ore-dressing tailing of bauxite and slag

A geopolymer was synthesized by calcined ore-dressing tailing of bauxite ( containing approximately 25% fly ash) and slag. The evolution of the micro-morphology of this geopolymer within 6 years was investigated. The typical characteristics of the crystalline precipitation and the morphology of fly ash particles in 6-year-old geopolymer were also studied using the scanning electron microscopy. The results show that the tailing-slag based geopolymer exhibites the usual morphology of porous gels and becomes more and more compact with the increase of curing age. Some crystalline particles of calcium carbonate are detected in large pores and hollow sphere of fly ash in geopolymer at late ages due to carbonation. The residual spherical shell of fly ash is observed because of the reaction between these vitreous particles and alkali solution. Fly ash particles with the porous morphology and small spherical particles rich in ferrum are still presented in geopolymer at late ages due to their remarkably low reactivity.