亚硫酸钙在水泥水化过程中的作用机制研究

【作者】 姚建可；

【导师】 杨利群； 徐先宇；

【作者基本信息】 浙江大学 ， 材料学， 2002， 硕士

【摘要】 脱硫渣中硫主要以硫酸钙和亚硫酸钙形式存在，影响脱硫渣综合利用的主要因素是其中的亚硫酸钙在水泥水化中的行为。本文基于将脱硫渣用作水泥混合材，应用XRD、DTA、SEM等测试方法重点研究了在亚硫酸钙存在的情况下水泥的水化机理、浆体的微观结构和水泥石宏观性能的关系。 研究表明：（1）在脱硫渣中CaSO₃．1／2H₂O不具有石膏那样的调节水泥凝结时间的作用。1d强度比掺CaSO₄．2H₂O试样显著降低，3d以后强度两者相近。CaSO₃．1／2H₂O掺量在一定范围内变化，与水泥强度变化无明显相关性。60d的抗折、抗压强度与28d相比，增幅很小，有的甚至倒缩。（2）CaSO₃．1／2H₂O和CaSO₄．2H₂O双掺时，随着CaSO₃．1／2H₂O掺量的增加和CaSO₄．2H₂O的减少，对水泥凝结性能没有太大的影响，这主要是CaSO4．2H₂O在起作用。1d强度随着CaSO₃．1／2H₂O掺量的增加，有减小的趋势，28d的抗折强度与3d相比，增幅很小，有的甚至倒缩。（3）亚硫酸钙和铝酸盐矿物反应主要生成单硫型水化硫铝酸钙（3CaO．Al₂O₃．CaSO₃．11H₂O） 。在水化过程中有部分CaSO₃．1／2H₂O会氧化成CaSO₄，从而有C₃A．3CaSO₄．32H₂O生成，但数量不多。（4）CaSO₃．1／2H₂O与铝酸盐矿物反应生成3CaO．Al₂O₃．CaSO₃．11H₂O，引起水泥石的膨胀，在早期的膨胀率和3CaO．Al₂O₃．3CASO₄．31H₂O引起水泥石的膨胀相比要小。在28d以后，随着CaSO₃．1／2H₂O的继续溶解，能继续生成3CaO．Al₂O₃．CaSO₃．11H₂O引起水泥石的膨胀。（5）在Ca（OH）₂碱性条件下CaSO₃．1／2H₂O对矿渣的激发作用，和CaSO₄．2H₂O相比，相差甚远。（6）影响CaSO₃．1／2H₂O在水泥水化中行为的主要因素是CaSO₃．1／2H₂O中80₃^2-的溶出速率。CaSO₃．1／2H₂O在纯水中SO₃^2-的溶出速率远小于CaSO₄．2H₂O在纯水中SO₄^2-的溶出速率。1d时，溶液中[SO₃^2-]为8.7×10^-5mol／1，28d才有8.0×10^-4mol／l。而溶液中[SO4^2-]ld就有1.3×10^-2mol／1，远大于[SO3^2-]。更多还原

【Abstract】 In the flue gas desulfuration residue, the main forms of sulfur are calcium sulfate and calcium sulfite. The key factor to influence the application of flue gas desulfuration residue is the behavior of calcium sulfite in cement hydration. In this paper, we used X-ray Difrraction(XRD^ Scanning Electron Microscope(SEM) and Differential Thermal Analysis(DTA) to research the behavior of calcium sulfite in cement hydration and the influence of calcium sulfite on cement performance.The research results are: (1) Calcium sulfite can not retard the setting of Ordinary Portland Cement(OPC). With calcium sulfite addition, the cement’s Id compressive strength decrease drastically, 3 days’ compressive strength is just the same as that of OPC with calcium sulfate addition. The 60 days’ compressive strength, compared with that of 28 days’, increase a little, sometimes decrease. The proportion of calcium sulfite addition in cement, in some extent, has no conspicuous relevance of cement compressive strength. (2) Both addition of calcium sulfite and calcium sulfate in cement, calcium sulfite has no conspicuous influence on the cement setting time, because calcium sulfate can control the cement setting time. With the increasing of calcium sulfite adding proportion, the cement 1 day’s compressive strength decrease. The 28 days’ compressive strength, compared with 3 days’ compressive strength, increase a little, sometimes decrease. (3) The initial hydration reactions of aluminates with calcium sulfite forms a lamellar phase(3CaO.A!2O3.CaSO3.11H2O). Ettringite-type mineral containing sulfite did not occur. By oxidation of sulfite to sulfate, 3CaO.Al2O3.3CaSO.4.32H2O occur. (3)The hydration reaction of aluminates with calcium sulfite forms 3CaO.Al2O3.CaSO3.11H2O . 3CaO.Al2O3.CaSO3.llH2O formation can lead to concrete expansion. The expansion magnitude of 3CaO.Al203.CaSO3.11H2O at early days is lower than expansion of ettringite.After 28 days, the expansion of 3CaO.Al2O3.CaSO3.11H2O continue to develop. (5) Under the alkali condition of calcium hydrate, calcium sulfite can not activate the hydration of slag as calcium sulfate do. (5)The key factor to influence the behavior of calcium sulfite in the cement hydration is the dissolving rate of calcium sulfite. The dissolving rate of calcium sulfite in water is lower than that of calcium sulfate. The concentration of SO^2’ at 1 day is 8.7X 10~5mol/l, at 28 days is only 8.0 X10"4 mol/1. The concentration of SO42" at 1 day is 1.3 X10’2 mol/1.更多还原