【作者】 李利；

【导师】 吴芳；

【作者基本信息】 重庆大学 ， 材料科学与工程， 2011， 硕士

【摘要】 赤泥是铝土矿生产氧化铝后排放的细颗粒强碱性固体废渣,按现有工艺,生产1t氧化铝一般排出赤泥0.8～1.76t。我国是氧化铝生产大国,每年氧化铝企业赤泥排放量在1000万t以上,而目前赤泥综合利用率仅为4%,累积堆存量已高达2亿t,因此充分利用赤泥,变废为宝是一项迫切的任务。砂浆是土木工程建设中用量较大的建筑材料,据统计我国砂浆每年需求量约为10亿t,用赤泥制备水泥砂浆,是综合利用赤泥的有效途径。本文通过赤泥-水泥胶凝材料体系水化硬化特性研究,确定了赤泥的掺量范围,并在分析矿物外加剂、化学外加剂对砂浆工作性能和力学性能影响的基础上,配制出了性能良好、成本较低的赤泥干混砌筑砂浆。论文还对砂浆的吸水性、泛碱、抗碳化性、干缩性、抗硫酸盐侵蚀性能进行了研究。主要结论如下:(1)赤泥-水泥胶凝材料体系水化产物的孔溶液碱度随赤泥掺量的增加而增大,但掺入赤泥并不会引起胶凝材料水化后期孔溶液碱度的增加。赤泥-水泥胶凝材料体系的水化产物XRD分析、化学结合水分析及强度分析表明赤泥对普通硅酸盐水泥早期水化和强度发展有促进作用。(2)赤泥干混砌筑砂浆最佳配制参数为:赤泥掺量30%,超量取代系数β1.63,水胶比0.6。赤泥与磷渣、矿渣或粉煤灰复掺对赤泥砂浆工作性和力学性能起到一定改性作用。赤泥与矿渣复掺时对砂浆性能的改善最为明显,25%赤泥和25%矿渣复掺的砂浆28d抗折和抗压强度为7.5MPa、26.4MPa。适量的化学外加剂对赤泥砂浆的工作性能和力学性能也有不同程度的改善,其中减水剂、消泡剂、三乙醇胺早强剂、可分散乳胶粉最佳掺量分别为0.25%、0.2%、0.04%、2.0%左右。配制的赤泥干混砌筑砂浆性能良好,成本较低。(3)掺入赤泥使砂浆的孔隙率增大,吸水率增加。赤泥与磷渣或矿渣复掺能改善砂浆的孔隙结构,使砂浆吸水率下降。赤泥与磷渣、矿渣或粉煤灰复掺能抑制赤泥砂浆泛碱,其中赤泥与粉煤灰复掺对砂浆泛碱抑制作用最为明显。(4)赤泥的掺入使砂浆的抗碳化能力降低。但赤泥与磷渣、矿渣或粉煤灰复掺对赤泥砂浆的抗碳化能力有所改善。赤泥和粉煤灰、矿渣复掺的水泥砂浆在各龄期的干缩都明显小于基准砂浆。赤泥与粉煤灰复掺的砂浆抗硫酸盐侵蚀能力优于基准砂浆,赤泥与磷渣复掺的砂浆虽然抗蚀系数低于基准砂浆,但随着龄期增长抗硫酸侵蚀能力却不降反增。更多还原

【Abstract】 Red mud is a high alkaline and fine solid waste generated during aluminum product raised from bauxite. It is reported that production of 1 tonne of metallic aluminum generates about 0.8-1.76 tonnes of red mud.With the increasing alumina production in China, annually there are about 10 million tonnes of red mud being disposed from alumina plants. It was estimated that the total amount of red mud was up to 200 million tones but only about 4% of the red mud is effective utilization. So taking full advantage and expanding application of red mud as a useful material is a exigent mission。Mortar is a high consumption building material in earth wood building and the requirement is approximately 1000 million tones a year. Application red mud to mortar production is a effective utilized method.The characterization of red mud-cement binder systems hydration and hardening was studied. Through it the dosage of red mud was determined. Based on the influence of mineral admixture and chemical additive on the workability and mechanical properties of mortar a kind of high performance and low cost dry-mixed masonry mortar with red mud was prepared. The absorbing property, efflorescence, carbonization resistance, dry-shrinkage, sulfate attack resistance of mortar were also investigated. The main conclusion as follows:(1) There is an increase in alkalinity of red mud-cement binder system pore solution with the increase dosage of Bayer red-mud. But red mud would not increase the late alkalinity of binder system pore solution. The analysis on X-ray differaction(XRD), chemical combined water, sterngth of red mud–cement binder system hydration product indicate that red mud can promote the ordinary portland cement early age hydration and strength development.(2)The optimum preparation parameters of red mud dry-mixed masonry mortar are that: the red mud content is 30%; excessive replacement coefficientβis 1.63;the water-binder ration is 0.6.The red mud mixed with phosphorous slag, blast furnace slag or fly ash can improve the workability and mechanical property of red mud mortar. The flexural strength and compressive strength of mortar are 7.5MPa and 26.4MPa respectively when mixed with 25% red mud and 25% blast furnace slag, which was obviously enhanced. The workability and mechanical property of red mud mortar can be improved with appropriate amount chemical additive as well. The optimum dosage of water reducer, defoaming agent, TEA accelerator and polymer dispersion powder are about 0.25%, 0.2%, 0.04%, 2.0% separately. This red mud dry-mixed masonry mortar has good performance and low cost.(3) The porosity and water absorption of mortar both increased with red mud. The red mud mortar efflorescence can be inhibited by mixing red mud with phosphorous slag, blast furnace slag or fly ash, especially when mixing red mud and fly ash.(4) The mortar carbonation resistance was decreased with red mud. However this can be modified by mixing red mud with phosphorous slag, blast furnace slag or fly ash. The mortar dry shrinkage mixed with red mud and fly ash, or red mud and blast furnace slag is obviously lower than reference mortar. The sulfate attack resistance of mortar with red mud and fly ash is superior to reference mortar. Although the corrosion resistance coefficient of mortar with red mud and phosphorous slag is less than reference mortar, its sulfate attack resistance property can be improved as age prolonged.更多还原