镍石膏复合胶凝材料的制备及其性能研究

发布时间：2018-02-22 16:23

本文关键词： 镍石膏复合胶凝材料钛矿渣激发剂改性泡沫混凝土　出处：《西南科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：镍石膏是采用加压酸浸法提镍过程中产生的一种新型的工业副产石膏,其性质与磷石膏相似。目前,我国工业副产石膏的排放量远远超过利用量,其堆存量超过了 8亿吨,工业副产石膏的堆积占用了大量土地,并污染环境、浪费资源。本文利用未经处理的镍石膏与钛矿渣、生石灰等原料制备了镍石膏复合胶凝材料。但是,由于镍石膏中可溶磷含量高,且钛矿渣活性低,导致镍石膏复合胶凝材料存在凝结慢,强度低的问题,因此选择加入促凝剂和高活性掺合料对其进行改性,研究改性后的镍石膏复合胶凝材料的长期强度、耐水性等性能,利用镍石膏复合胶凝材料改性后的最优配方制备泡沫混凝土,并研究了水灰比、泡沫掺量、减水剂掺量等因素对其性能的影响。研究结果表明:镍石膏中的可溶性磷会对体系的凝结时间和强度产生不良影响,随着镍石膏掺量的增加,基体的强度降低,因此,镍石膏的掺量不宜过高,基于废渣资源化利用和镍石膏复合胶凝材料的综合性能考虑,确定镍石膏掺量为40%。单掺生石灰、NaOH和水玻璃作为激发剂时,生石灰的激发效果最好,最佳掺量为6～8%,而NaOH和水玻璃掺量较少时不能激发基体产生强度。相较镍石膏而言,钛矿渣对镍石膏复合胶凝材料早期性能影响更大。加入水泥替代部分钛矿渣可以提高基体的早期和后期强度,其与生石灰共同激发,大大提高了基体的致密度,但水泥的掺量不宜超过10%。硫铝酸盐水泥、KAl(SO4)2.12H2O 和 Al2(SO4)3.18H2O 等促凝剂的加入显著缩短了凝结时间,但是对强度影响较小;高性能掺合料偏高岭土和硅灰对凝结时间的影响较小,但是均能提高基体的早期和后期强度,偏高岭土的作用更强。硫铝酸盐水泥与偏高岭土复掺既能缩短凝结时间又能提高基体的强度;在硫铝酸盐水泥和偏高岭土掺量分别为2%和4%时制备出了初凝、终凝时间为132min和298min,3d、7d和28d抗压强度为6.45MPa、13.32MPa和23.96MPa的镍石膏复合胶凝材料。蒸养时早期强度大大增加,其后期强度基本与自然养护试样相当。改性后试样的强度随龄期延长继续增加,耐水性显著提高。利用改性后的镍石膏复合胶凝材料作为胶材,在水灰比为0.45,减水剂掺量为0.25%,LiOH掺量为0.2%时,在不同的泡沫掺量情况下可以制备出性能满足国标要求的A04～A10级泡沫混凝土。
[Abstract]:Nickel gypsum is a new type of industrial by-product gypsum produced in the process of nickel extraction by pressurized acid leaching. Its properties are similar to that of phosphogypsum. At present, the discharge amount of industrial by-product gypsum in China is far more than the utilization amount, and its heap stock exceeds 800 million tons. The accumulation of industrial by-product gypsum occupies a large amount of land, pollutes the environment and wastes resources. In this paper, nickel gypsum composite cementitious material was prepared from raw materials such as untreated nickel gypsum, titanium slag, quicklime and so on. Due to the high content of soluble phosphorus in nickel gypsum and the low activity of titanium slag, the nickel gypsum composite cementitious material has the problems of slow setting and low strength. Therefore, it is modified by adding coagulant and high active admixture. The long-term strength and water resistance of the modified nickel-gypsum composite cementing material were studied. The optimum formulation of the modified nickel-gypsum composite cementitious material was used to prepare the foamed concrete, and the water-cement ratio and foam content were also studied. The results show that the soluble phosphorus in the nickel gypsum has a negative effect on the setting time and strength of the system, and the strength of the matrix decreases with the increase of the content of nickel gypsum. The amount of nickel gypsum should not be too high. Considering the utilization of waste slag and the comprehensive properties of nickel-gypsum composite cementing material, it is determined that the amount of nickel gypsum is 40%. When NaOH and sodium silicate are used as activators, the activation effect of quicklime is the best. The optimum addition amount is 6 ~ 8%, but when the content of NaOH and sodium silicate is small, the matrix strength can not be excited. Compared with nickel gypsum, The effect of titanium slag on the early performance of nickel-gypsum composite cementitious material is more significant. Adding cement to replace part of titanium slag can improve the early and late strength of matrix, which is excited with quicklime and greatly improves the density of matrix. But the content of cement should not exceed 10. The addition of coagulant such as KAlso _ 4H _ 2O and Al2(SO4)3.18H2O obviously shortens the setting time, but has little effect on the strength, and the high performance admixture metakaolin and silica fume have little effect on the setting time. However, both of them can improve the early and late strength of the matrix, and the effect of metakaolin is stronger. The addition of sulphoaluminate cement and metakaolin can not only shorten the setting time but also improve the strength of the matrix. When the content of sulphoaluminate cement and metakaolin were 2% and 4 respectively, the initial setting was prepared, and the final setting time was 132min and 298min respectively. The compressive strength of nickel gypsum composite was 6.45MPa (13.32MPa) and 23.96MPa (28d) respectively. The later strength of the modified sample is similar to that of the natural curing sample. The strength of the modified sample continues to increase with the increase of age, and the water resistance of the modified sample increases significantly. The modified nickel-gypsum composite cementing material is used as the cementing material. When the water-cement ratio is 0.45 and the water reducer content is 0.25 and LiOH is 0.2, the A04A10 foam concrete with different foam content can be prepared.
【学位授予单位】：西南科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ177.375

【相似文献】