硫氧镁水泥基轻质材料的制备与基本性能

发布时间：2018-03-29 09:27

本文选题：改性硫氧镁水泥　切入点：稻壳　出处：《哈尔滨工业大学》2017年硕士论文

【摘要】：硫氧镁水泥是一种由轻烧氧化镁粉与适当浓度的硫酸镁溶液混合搅拌、凝结硬化而具有强度的无机胶凝材料。由于主要组份氧化镁的煅烧温度远低于硅酸盐水泥熟料的烧成温度,具有能耗低、生产工艺简单、成本低的优点,同时,硫氧镁水泥还具有良好的耐火性、耐热性、密度低、导热系数低、与不同材料的粘结力强等优点。因此,作为一种新型无机胶凝材料,硫氧镁水泥被广泛的应用于制作轻质墙板、耐火构件、保温隔热板等。针对硫氧镁水泥存在的强度偏低、耐水性差和收缩大等不足,本文首先研究了外掺少量柠檬酸、柠檬酸三钠及硼酸对硫氧镁水泥基本性能的改善效果;通过掺泡沫、稻壳及其两者复掺的方式制备了硫氧镁水泥轻质材料,并研究了硫氧镁水泥轻质材料的强度、密度、导热系数、干燥收缩以及干湿循环处理对其强度、体积变形的影响。并利用XRD、FTIR、DTA-TG、SEM及超景深显微镜测试方法分析了柠檬酸、柠檬酸三钠及硼酸对硫氧镁水泥的改性作用机理及硫氧镁水泥轻质材料的微观结构特征。结果表明:硫氧镁水泥的强度随着氧硫比的提高和水硫比的降低而提高。掺加柠檬酸、柠檬酸三钠及硼酸后硫氧镁水泥体系中生成了一种新的呈晶须状的针棒状晶体5·1·7相。由于这些针棒状5·1·7相交叉连生,填充孔隙与裂缝,使原本疏松的结构变得致密,从而改善硫氧镁水泥石的强度、耐水性及干燥收缩性能。柠檬酸、柠檬酸三钠、硼酸的最佳掺量分别为0.5%、2.5%、0.5%。其中,柠檬酸效果最好,可使硫氧镁水泥的28d强度和软化系数提高104.8%和61.09%,干燥收缩降低了32.81%。分别通过掺入泡沫、稻壳或两者复掺制备了体积密度分别为450~1685kg/m3、759~1721kg/m3、544~1268kg/m3,28天抗压强度分别为1.1~47.4MPa、2.9~70.4MPa、1.1~11.2MPa的硫氧镁水泥基轻质材料。所制备轻质材料的抗压强度、导热系数分别随着体积密度呈现指数函数和线性增长关系。硫氧镁水泥基轻质材料的干燥收缩值随着泡沫掺加量出现先降低后增大的变化规律,而稻壳的掺入会增大干燥收缩。随着干湿循环次数增多,硫氧镁水泥基轻质材料的强度不断降低,收缩值不断增大,但在稻壳掺量较少时反而出现膨胀现象。
[Abstract]:Magnesium sulfate cement is a mixture of light burned magnesium oxide powder and a suitable concentration of magnesium sulfate solution. Inorganic cementitious material with solidification and hardening. Because the calcination temperature of magnesium oxide, the main component, is far lower than that of Portland cement clinker, it has the advantages of low energy consumption, simple production process and low cost, at the same time, Magnesium sulfide cement also has the advantages of good fire resistance, heat resistance, low density, low thermal conductivity, strong adhesion to different materials, etc. Therefore, as a new inorganic cementitious material, Magnesium sulfide cement is widely used in making light wall panels, fire-resistant components, thermal insulation boards, etc. In view of the shortcomings of magnesium sulfide cement, such as low strength, poor water resistance and large shrinkage, a small amount of citric acid was added to the cement. The effects of trisodium citrate and boric acid on the basic properties of magnesium sulfide cement were studied. The effects of thermal conductivity, drying shrinkage and drying and wet cycle treatment on the strength and volume deformation of citric acid were analyzed by means of XRDX FTIR DTA-TGG SEM and hyperfield depth microscope. The mechanism of modification of magnesium sulfate cement by trisodium citrate and boric acid and the microstructure of magnesium sulfate cement were studied. The results showed that the strength of magnesium sulfate cement increased with the increase of oxygen / sulfur ratio and the decrease of water / sulfur ratio. A new whisker like needle-rod crystal 517 phase was formed in trisodium citrate and post-boric acid magnesium sulfide cement system. Due to the intersecting of these needle-rod phase 517, the original loose structure became compact due to the filling of pores and cracks. In order to improve the strength, water resistance and drying shrinkage of magnesium thio cement, the optimum content of citric acid, trisodium citrate and boric acid is 0.5%, 2.5% and 0.5% respectively. Among them, citric acid has the best effect. The 28d strength and softening coefficient of MgSO _ 2 cement were increased by 104.8% and 61.09%, and the drying shrinkage was reduced by 32.81%. The volume density of rice husk or both was 450,1685kg / m3759g / 1721kg / m3544 / 1268kg / m3 / m3 respectively. The compressive strength of the lightweight material was 1.1 ~ 47.4 MPA / m ~ (-1) ~ (-1) MPA respectively for 28 days, and the compressive strength of the prepared lightweight material was as follows: (1) mg _ (2) O _ (2) O _ (2) O _ (2) (mg _ (2) O _ (2)) (mg _ (2) O _ (2)) cement based material. The coefficient of thermal conductivity shows exponential function and linear increase with volume density. The drying shrinkage value of magnesium thiooxygen-based cement material decreases first and then increases with the increase of foam content. With the increase of dry-wet cycle times, the strength and shrinkage value of MgSO-based lightweight materials decreased and the shrinkage value increased, but when the amount of rice husk was less, the swelling phenomenon appeared.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528

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