典型重金属离子对碱矿渣水泥水化及结构形成的影响
发布时间：2018-08-22 17:24
【摘要】：随着我国经济的迅猛发展,环境污染问题日渐严重,给社会带来了很大压力,重金属废弃物的处置也越来越受到重视。目前水泥固化法是处理重金属废弃物的重要方法之一。传统硅酸盐水泥基材料固化重金属废弃物存在固化体增容比大、重金属浸出浓度高、耐久性欠佳、抗酸和抗硫酸盐性能差等明显的缺陷。碱矿渣水泥的水化产物主要是低钙硅比的C-S-H凝胶,能更有效固封有毒重金属离子,是一种环境效益和经济效益显著的新型低碳型胶凝材料。研究重金属离子对碱矿渣水泥水化及结构形成的影响,为深入认识碱矿渣水泥石固结重金属离子的机理提供技术基础,对促进其应用具有重要社会意义。本文采用水胶比0.3,碱当量5%(以Na2O当量计)的配比来研究Cr6+/Pb2+/Zn2+/Cd2+四种重金属离子对碱矿渣水泥水化放热特性、凝结、硬化及强度等性能影响,结合孔结构测试、XRD、FT-IR、SEM等微观测试手段,分析了重金属离子的加入对其水化产物结构的影响。研究结果表明:1)Cr6+掺量低于2%条件下,水玻璃为碱组分时,随着掺量的增加,碱矿渣水泥的水化进程延迟,水化热降低,凝结时间延长,抗压强度先增加后降低。微观测试表明水玻璃为碱组分时,Cr6+的掺入使得碱矿渣水泥石中没有发现新的晶体生成,其小孔径孔增多,孔隙增加,孔结构细化,且水化产物结构部分区域松散不够致密,对水化产物的结构有一定的影响。2)Pb2+掺量低于2%条件下,同Cr6+一样,水玻璃为碱组分时,随着掺量的增加,碱矿渣水泥的水化进程延迟,水化热降低,凝结时间延长,抗压强度先增加后降低。微观测试表明水玻璃作为碱组分时Pb2+的掺入对碱矿渣水泥的孔隙影响不大,水化产物结构裂缝增多变宽,对水化产物的结构有一定的影响。3)Zn2+掺量低于1%条件下,不同碱组分时,随着掺量的增加,碱矿渣水泥的水化进程延迟,水化热降低,凝结时间明显延长,抗压强度逐渐降低。但是当水玻璃模数为2.48时,掺量过高会使碱矿渣水泥出现速凝现象。微观测试表明水玻璃为碱组分时掺入Zn2+的碱矿渣水泥没有发现新的晶体生成,但其孔隙减少,且其水化产物结构部分区域松散不够致密。4)Cd2+掺量低于2%条件下,Na OH为碱组分时,随着掺量的增加,碱矿渣水泥的水化进程延迟,水化热降低,凝结时间延长。模数1.5的水玻璃为碱组分时,Cd2+具有促凝作用,模数2.48的水玻璃为碱组分时,掺量越大,碱矿渣水泥的初凝时间先略微增加后减少,终凝时间越长。Cd2+对碱矿渣水泥石的抗压强度的影响不大;水玻璃作为碱组分时掺入Cd2+的碱矿渣水泥没有发现新的晶体生成,其孔隙减少,水化产物结构疏松不够致密。
[Abstract]:With the rapid development of economy in China, the environmental pollution problem is becoming more and more serious, which brings great pressure to the society, and the disposal of heavy metal wastes is paid more and more attention. At present, cement curing method is one of the important methods to treat heavy metal waste. Traditional silicate cement based materials have some obvious defects such as high capacity ratio of solidified heavy metal, high concentration of heavy metal leaching, poor durability, poor resistance to acid and sulfate, and so on. The hydration product of alkali slag cement is mainly C-S-H gel with low ratio of calcium to silicon, which can effectively immobilize toxic heavy metal ions. It is a new type of low carbon cementitious material with significant environmental and economic benefits. The influence of heavy metal ions on the hydration and structure formation of alkali slag cement is studied, which provides a technical basis for further understanding the mechanism of consolidation of heavy metal ions in alkali slag cement, and has important social significance in promoting its application. In this paper, the effects of Cr6 / Pb _ 2 / Zn _ 2 / CD _ 2 heavy metal ions on the hydration heat release characteristics, condensation, hardening and strength of alkali slag cement were studied by using the ratio of water to binder 0.3 and alkali equivalent 5% (calculated as Na2O equivalent). The effect of the addition of heavy metal ions on the structure of hydration products was analyzed by means of microcosmic measurement of pore structure, such as XRDX FT-IRU SEM. The results show that when the content of Cr6 is less than 2%, the hydration process of alkali slag cement is delayed, the hydration heat decreases, the setting time is prolonged, and the compressive strength increases first and then decreases with the increase of water glass content. The microcosmic test shows that when sodium silicate is alkali component, the addition of Cr6 causes no new crystal formation in alkali slag cement, and the small pore size increases, the pore structure is fine, and the structure of hydration product is loose and not compact enough. The hydration process of alkali slag cement is delayed, the hydration heat decreases and the setting time is prolonged with the increase of the content of water glass, when the content of Cr6 is less than 2%, the hydration process of alkali slag cement is delayed, the hydration heat decreases, and the setting time is prolonged with the increase of the content of water glass. The compressive strength first increases and then decreases. The microcosmic test shows that when sodium silicate is used as alkali component, the addition of Pb2 has little effect on the pore size of alkali slag cement, and the crack of hydration product increases and widens, which has a certain influence on the structure of hydration product (3) when the content of Zn2 is less than 1%, the different alkali components can be obtained. With the increase of the content of alkali slag cement, the hydration process of alkali slag cement is delayed, the hydration heat decreases, the setting time is obviously prolonged, and the compressive strength decreases gradually. However, when the modulus of sodium silicate is 2.48, the rapid setting of alkali slag cement will occur when the content of sodium silicate is too high. Microscopic measurements showed that no new crystal formation was found in alkali slag cement mixed with Zn2 when sodium silicate was alkali component, but the pore size was decreased, and the structure of hydration product was loose and not compact enough.) when the content of Cd2 was less than 2%, the sodium hydroxide was the base component. With the increase of the content of alkali slag cement, the hydration process of alkali slag cement is delayed, the hydration heat decreases and the setting time is prolonged. The sodium silicate with modulus 1.5 has the effect of promoting coagulation. When the water glass with modulus 2.48 is the alkali component, the initial setting time of alkali slag cement increases slightly and then decreases with the increase of the content of water glass with modulus 2.48. The longer the final setting time, the less the effect on the compressive strength of alkali slag cement, but no new crystal formation was found in the alkali slag cement mixed with Cd2 when sodium silicate was used as an alkali component, the porosity was reduced, and the structure of hydration product was loose and not dense enough.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ172.1
本文编号：2197799
[Abstract]:With the rapid development of economy in China, the environmental pollution problem is becoming more and more serious, which brings great pressure to the society, and the disposal of heavy metal wastes is paid more and more attention. At present, cement curing method is one of the important methods to treat heavy metal waste. Traditional silicate cement based materials have some obvious defects such as high capacity ratio of solidified heavy metal, high concentration of heavy metal leaching, poor durability, poor resistance to acid and sulfate, and so on. The hydration product of alkali slag cement is mainly C-S-H gel with low ratio of calcium to silicon, which can effectively immobilize toxic heavy metal ions. It is a new type of low carbon cementitious material with significant environmental and economic benefits. The influence of heavy metal ions on the hydration and structure formation of alkali slag cement is studied, which provides a technical basis for further understanding the mechanism of consolidation of heavy metal ions in alkali slag cement, and has important social significance in promoting its application. In this paper, the effects of Cr6 / Pb _ 2 / Zn _ 2 / CD _ 2 heavy metal ions on the hydration heat release characteristics, condensation, hardening and strength of alkali slag cement were studied by using the ratio of water to binder 0.3 and alkali equivalent 5% (calculated as Na2O equivalent). The effect of the addition of heavy metal ions on the structure of hydration products was analyzed by means of microcosmic measurement of pore structure, such as XRDX FT-IRU SEM. The results show that when the content of Cr6 is less than 2%, the hydration process of alkali slag cement is delayed, the hydration heat decreases, the setting time is prolonged, and the compressive strength increases first and then decreases with the increase of water glass content. The microcosmic test shows that when sodium silicate is alkali component, the addition of Cr6 causes no new crystal formation in alkali slag cement, and the small pore size increases, the pore structure is fine, and the structure of hydration product is loose and not compact enough. The hydration process of alkali slag cement is delayed, the hydration heat decreases and the setting time is prolonged with the increase of the content of water glass, when the content of Cr6 is less than 2%, the hydration process of alkali slag cement is delayed, the hydration heat decreases, and the setting time is prolonged with the increase of the content of water glass. The compressive strength first increases and then decreases. The microcosmic test shows that when sodium silicate is used as alkali component, the addition of Pb2 has little effect on the pore size of alkali slag cement, and the crack of hydration product increases and widens, which has a certain influence on the structure of hydration product (3) when the content of Zn2 is less than 1%, the different alkali components can be obtained. With the increase of the content of alkali slag cement, the hydration process of alkali slag cement is delayed, the hydration heat decreases, the setting time is obviously prolonged, and the compressive strength decreases gradually. However, when the modulus of sodium silicate is 2.48, the rapid setting of alkali slag cement will occur when the content of sodium silicate is too high. Microscopic measurements showed that no new crystal formation was found in alkali slag cement mixed with Zn2 when sodium silicate was alkali component, but the pore size was decreased, and the structure of hydration product was loose and not compact enough.) when the content of Cd2 was less than 2%, the sodium hydroxide was the base component. With the increase of the content of alkali slag cement, the hydration process of alkali slag cement is delayed, the hydration heat decreases and the setting time is prolonged. The sodium silicate with modulus 1.5 has the effect of promoting coagulation. When the water glass with modulus 2.48 is the alkali component, the initial setting time of alkali slag cement increases slightly and then decreases with the increase of the content of water glass with modulus 2.48. The longer the final setting time, the less the effect on the compressive strength of alkali slag cement, but no new crystal formation was found in the alkali slag cement mixed with Cd2 when sodium silicate was used as an alkali component, the porosity was reduced, and the structure of hydration product was loose and not dense enough.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ172.1
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