碱式硫酸镁水泥耐水性研究

发布时间：2018-02-09 20:16

本文关键词： 碱式硫酸镁水泥摩尔比改性剂矿物掺合料耐水性　出处：《哈尔滨理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：本文研究了碱式硫酸镁水泥原材料中摩尔比、改性剂掺量和矿物掺合料种类与掺量对水泥浸水前后抗压强度的影响,探索组成材料对碱式硫酸镁水泥耐水性能的影响规律。通过X射线衍射和扫描电子显微镜试验研究其浸水前后水化产物和显微结构的变化,分析了组成材料对碱式硫酸镁水泥耐水性能的改善机理。试验结果表明,碱式硫酸镁水泥耐水性能受原材料配比和矿物掺合料掺量影响较大。当改性剂掺量相同时,碱式硫酸镁水泥原材料配比中MgO:MgSO4摩尔比越大,水泥试样在气硬条件下强度越高,耐水性能越好。当H2O:MgSO4摩尔比固定,MgO:MgSO4摩尔比为7时,水泥试样浸水60天时强度损失率为33%,MgO:MgSO4摩尔比为9时,水泥试样强度损失率为17.9%。当MgO:MgSO4摩尔比固定,碱式硫酸镁水泥原材料配比中H2O:MgSO4摩尔比越大,水泥试样气硬条件下强度越低,耐水性能越差。当H2O:MgSO4摩尔比由20增大到22时,浸水60天的水泥试样强度损失率由17.9%增大到48.2%。当原材料摩尔比相同时,碱式硫酸镁水泥试样抗压强度和软化系数在改性剂掺量为0.1%~1.0%范围内,随改性剂掺量的增加而提高,改性剂掺量为1%时获得最大值。当在碱式硫酸镁水泥中加入一定掺量的粉煤灰、矿渣和硅灰,均可提高水泥的耐水性能。三种矿物掺合料掺量为轻烧氧化镁质量的30%时,对碱式硫酸镁水泥耐水性能的改善效果最佳,其中掺加30%粉煤灰的碱式硫酸镁水泥浸水70天后软化系数最高可达0.97。碱式硫酸镁水泥水化产物及显微结构分析表明,较高的MgO:MgSO4摩尔比、较低的H2O:MgSO4摩尔比和与之相适应的改性剂掺量,更有利于碱式硫酸镁水泥中针杆状晶体5Mg(OH)2·MgSO4·7H2O的生成,因而耐水性能较好。粉煤灰、矿渣和硅灰等矿物掺合料由于颗粒较细,可以填充水泥石内部的孔隙,使水泥石结构更加密实,从而提高碱式硫酸镁水泥耐水性能。
[Abstract]:In this paper, the influence of the mole ratio of basic magnesium sulfate cement, the amount of modifier and mineral admixture on the compressive strength of cement before and after soaking was studied. The effects of composition materials on the water resistance of basic magnesium sulfate cement were investigated. The changes of hydration products and microstructure before and after immersion were studied by X-ray diffraction and scanning electron microscopy (SEM). The mechanism of improving the water resistance of basic magnesium sulfate cement is analyzed. The experimental results show that the water resistance of basic magnesium sulfate cement is greatly affected by the ratio of raw materials and mineral admixture, and when the content of modifier is the same, The higher the molar ratio of MgO:MgSO4 to MgSO4 in raw material ratio of basic magnesium sulfate cement is, the higher the strength of cement sample is under the condition of air hardening, and the better the water resistance is. When the molar ratio of H _ 2O _ 2: MgSO _ 4 is fixed, the molar ratio of MgO _ 2O _ 4 to MgSO _ 4 is 7:00. After 60 days of soaking, the strength loss rate of cement sample is 33% and 9:00, and the loss rate of cement sample strength is 17.9. When the molar ratio of MgO:MgSO4 is fixed, the ratio of H _ 2O: MgSO _ 4 in the ratio of H _ 2O _ 2 to MgSO _ 4 in raw material of basic magnesium sulfate is higher, the strength of cement sample under air-hardening condition is lower. When the molar ratio of H _ 2O: MgSO _ 4 was increased from 20 to 22:00, the strength loss rate of cement samples immersed in water for 60 days increased from 17.9% to 48.2 percent. When the molar ratio of raw materials was the same, The compressive strength and softening coefficient of basic magnesium sulfate cement samples increased with the increase of modifier content in the range of 0.1% or 1.0%. When the content of modifier is 1, the maximum value can be obtained. When a certain amount of fly ash, slag and silica fume is added to the basic magnesium sulfate cement, the water resistance of the cement can be improved. The water resistance of basic magnesium sulfate cement is the best, and the softening coefficient of basic magnesium sulfate cement mixed with 30% fly ash can reach to 0.97 after 70 days of immersion. The hydration products and microstructure of basic magnesium sulfate cement are analyzed. The higher molar ratio of MgO:MgSO4, the lower molar ratio of H _ 2O: MgSO _ 4 and the corresponding amount of modifier are more favorable to the formation of needle-shaped crystal 5MgOH2 路MgSO4 路7H2O in basic magnesium sulfate cement, so the water resistance of fly ash is better. The mineral admixtures such as slag and silica fume can fill the internal pores of cement stone because of the fine particles, so that the structure of cement stone is more dense, thus improving the water resistance of basic magnesium sulfate cement.
【学位授予单位】：哈尔滨理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ172.1

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