赤泥和磷渣调控水泥混凝土界面过渡区微结构的研究

Effects of Red Mud and Phosphorous Slag on Interfacial Transition Zone Microstructure of Cement Concrete

混凝土是由硬化浆体、骨料和界面过渡区组成的多相复合材料,以贵州典型赤泥、磷渣为原料,采用微机控制抗压抗折试验机、全自动压汞仪和扫描电子显微镜研究赤泥、磷渣对水泥混凝土力学性能及微观结构的影响。结果表明:赤泥和磷渣均能导致28 d养护龄期的水泥净浆硬化体力学性能下降,20%~30%用量的磷渣或10%用量的赤泥对水泥混凝土过渡区具有一定优化作用;纯水泥混凝土、掺赤泥或磷渣水泥混凝土微孔直径均主要分布在20~100 nm区间,在养护龄期28 d时混凝土过渡区均发生了不同程度的收缩,不利于混凝土力学性能的提高;赤泥的高碱性导致过渡区及基体内微孔数量增多,晶体较大,而磷渣粉的微集料效应、火山灰活性效应导致浆体中孔数量减少和晶体较小。

Concrete is a kind of polyphase composite composed of hardened paste,aggregate and interfacial transition zone.Mechanical properties and microstructure of cement concrete with a certain amount of typical red mud and phosphorous slag in Guizhou province were researched by microcomputer controlled compressive and flexure testing machine,automatic mercury porosimeter and scanning electron microscope. The results show that both red mud and phosphorous slag can lead to the decline of physical and chemical properties of the cement paste hardening body during the curing period of 28 d.20%-30% phosphorous slag or 10% the red mud has certain optimization effect on the interfacial transition zone of cement concrete. The pore diameter of pure cement concrete,red mud-cement concrete or phosphorous slag-cement concrete is mainly distributed in the range of 20-100 nm and the shrinkage occurs to varying degrees at the curing age of 28 d,which is not conducive to the improvement of mechanical properties of concrete. The number of micropores is more and crystals are larger because of the high alkalinity of red mud. However,the microaggregate effect and pozzolanic activity effect of phosphorous slag powder lead to the decrease of the number of pores and smaller crystal size in the hardened paste.