氯氧镁水泥基材料干燥收缩的研究

研究了配合比、矿物掺合料、细骨料对氯氧镁水泥干燥收缩的影响,结果表明,随MgO/MgCl2摩尔比升高氯氧镁水泥干燥收缩增大;掺入粉煤灰导致氯氧镁水泥干燥收缩值增加,而硅灰+粉煤灰对干燥收缩有改善作用;砂的加入使水泥干燥收缩降低显著,而稻壳粉的加入,使干燥收缩加剧.     

氯氧镁水泥相稳定性的研究

为在生产和广泛使用氯氧镁水泥时提高氯氧镁水泥相稳定性,运用热力学方法对MgO-MgCl_2-H_2O体系水化产物的生成、溶解和相转化进行分析,并对不同MgO/MgCl_2摩尔比的氯氧镁水泥的耐水性和相变规律进行试验研究.结果表明,水泥石所处的溶液pH值对水化产物相稳定有较大影响,pH升高水化产物的溶解度减小,相稳定性提高;当pH值大于10.37时,溶液析出大量Mg(OH)_2使水化产物相稳定性变差.当摩尔比小于6时,随着摩尔比的增大,水化产物内部过量MgO增多使体系碱度提高,水化产物稳定性改善;当摩尔比大于6 时,水化产物中含过量MgO,由于较多Mg(OH)_2生成产生过大的结晶应力,引起水泥石结构破坏.     

氯氧镁水泥抗水性研究

讨论了硅粉、粉煤灰、磷酸盐、硫酸盐、复合外加剂等对提高氯氧镁水泥抗水性的作用；对氯氧镁水泥抗水性的微观结构进行了分析．分析结果认为，使用复合抗水剂效果最好．     

氯氧镁水泥热分解过程的研究

为探究氯氧镁水泥的热稳定性和循环利用的可能性,首先合成了纯的3·1·8和5·1·8相;然后用IR、XRD对其形成过程进行了表征;最后使用TG、DTA分别研究了两种相态的热分解过程,使用XRD表征了各阶段热分解产物的组成及相态.通过本论文的研究可以确定在150℃时3·1·8和5·1·8相失去结晶水而完全失去强度,进一步升高温度到400℃时,氢氧化镁失水,此时热分解产物可重新用做原料生产氯氧镁水泥.     

氯氧镁水泥研究新进展

本文详细综述了氯氧镁水泥的水化理论发展、氯氧镁水泥的组成与性能的主要影响因素、氯氧镁水泥制品改性进展、氯氧镁水泥制品的应用进展;探讨了MgO/MgCl2摩尔比、MgCl2溶液浓度、养护条件对氯氧镁水泥制备的影响;总结了无机物类改性、有机物类改性、活性矿物掺合料改性、纤维类改性、复掺改性对氯氧镁水泥各项性能的改性效果;分...     

察尔汗盐湖氯氧镁水泥的研究现状与发展前景

对中国青海察尔汗盐湖氯氧镁水泥的研究现状作了简要分析,并据此对综合开发盐湖资源,使用氯氧镁水泥的前景提出了一些看法。     

氯氧镁水泥耐水性能的研究

通过对氯氧镁水泥块、粉末及含少量防水改性剂的试样进行对比测定。研究了氯氧镁水泥的耐水性能，提出了寻找新的防水改性剂的途径。     

废玻璃改性氯氧镁水泥的研究

介绍了废玻璃改性氯氧镁水泥的方法,利用活性氧化镁、六水氯化镁和玻璃机械拌合形成氯氧镁水泥骨料,玻璃由粗玻璃和细玻璃组成,粒度分布范围在48～1 700μm之间.通过各原料的级配得到的氯氧镁水泥骨料,然后进行耐磨性,抗折,抗压以及对骨料的断面的SEM分析.研究结果表明玻璃级配料能很大程度改善了氯氧镁水泥的耐磨性,并能有效提高氯氧镁水泥的抗折与抗压强度.该方法充分利用了废旧玻璃资源,提高了废旧玻璃的回收利用率,为氯氧镁水泥的制备提供了新思路.     

氯氧镁水泥水化机理与水化动力学研究

本文时按５·１·８和３·１·８摩尔比配制的Ｍｇ（ＯＨ）２［及ＭｇＯ］与ＭｇＣＩｌ２水溶液反应的水化动力学作了较为详细的讨论。通过测定系统中固相结合氯离子的含量作为水化动力学的指标─—水化程度，同时测定水化后试件强度，结果表明，固相结合氯离子的含量与强度发展有较好的相关性。水化程度实质上反映了氯氧镁水泥的结构形成过程．通过Ｘ－ｒａｙ快速分析水化反应，追踪５·１·８相（特征峰值０．７５６ｎｍ）、Ｍｇ（ＯＨ）２晶相（特征峰值０．４７７ｎｍ）和ＭｇＯ晶相（特征峰值０．２１１ｎｍ）的变化，阐明了氯氧镁水泥水化反应初期，在结构形成过程中存在着一个凝胶阶段，随后水化相在凝胶表面析晶，并联接凝胶形成结晶结构网，凝胶的主要组成是Ｍｇ２＋、Ｃｌ－、ＯＨ－并以５·１·８相形成存在。     

水泥基复合材料界面过渡区体积分数的定量计算

为了计算水泥基复合材料的界面过渡区体积分数,采用最邻近表面分布函数和骨料比表面积2种方法,结合实际骨料的筛分曲线,给出了界面过渡区体积分数定量关系式．结果表明：单位体积水泥基复合材料中,当骨料的体积分数〈0．5,界面厚度〈50μm时,2种方法计算的误差约为10％;界面区厚度越小,2种方法计算的误差也越小．     

Influence of MgO/MgCl2 molar ratio on phase stability of magnesium oxychloride cement

Formation, solution and phase change of hydration products in MgO-MgCl₂-H₂O system was studied with thermodynamics method, and resistance to water immersion and phase change of magnesium oxychloride cement with different MgO/MgCl₂ molar ratio was experimented. The results show that pH value of immersion solution of cement paste has a remarkable influence on phase stability of hydration products. A higher pH value leads to a lower solubility and a better phase stability of hydration products. When the solution pH value is higher than 10.37, the precipitation of much Mg(OH)₂ crystal induces a worse phase stability of hydration products. With the increasing MgO/MgCl₂ molar ratio (lower than 6), the more amount of MgO in the hydration products enhances the alkalinity of solution and the phase stability is improved. However, when the MgO/MgCl₂ molar ratio is higher than 6 and the excessive MgO exsits in the hydration products, the cement paste may be damaged by the excessive crystallization stress of a great deal of Mg(OH)₂ formation. Funded by the National Natural Science Foundation of China(No. 50078019)     

多尺度纤维复合增强水泥基材料的力学性能

为改善水泥基材料抗拉强度低、韧性差以及易开裂等性能缺陷,采用微米级碳酸钙晶须和厘米级短切耐碱玻璃纤维复合增强高性能水泥基材料,并对不同纤维增强水泥基材料的基本力学性能进行研究.结果表明:微观碳酸钙晶须和宏观耐碱玻璃纤维均有利于水泥基材料力学性能的提高,且提高程度与纤维(或晶须)掺量及长度相关;采用碳酸钙晶须和耐碱玻璃纤...     

Self-healing Action of Permeable Crystalline Coating on Pores and Cracks in Cement-based Materials

The self-healing action of a permeable crystalline coating on the porous mortar was investigated by two times impermeability test. Moreover, the self-healing mechanism of cement-based materials with the permeable crystalline coating, was studied by SEM. The results indicate that the permeable crystalline coating not only seals the pores and cracks in mortar during its curing process, but also heals the permeable pathway caused by first impermeability test or cracks produced by freeze-thaw cycles . Therefore, cement-based materials can be improved by the permeable crystalline coating for the self-healing function. SEM images prove that the self-healing function is realized by generating a great quantity of non- soluble dendritic crystalline within the pores and cracks, which prevents the penetration of water and other liquids.     

Effects of the component and fiber gradient distributions on the strength of cement-based composite materials

1　IntroductionTheconceptofthefunctionallygradientmaterial(FGM)wasfirstproposedtwodecadesagobyMasayukietal[1] tohelpthedesignofheat resistantsystemsofspacecraftswhentheytraveledthroughtheastrosphere .Sincethen ,extensiveresearchesandapplicationsofFGMhavebeenconducted ,especiallyonceramicandmetalmaterials[2 6] ,butthestudyonthecement basedfunction allygradientmaterial (CFGM)onlystartedrecently[7] .FGMismadeoftwoormoredistinctmaterialsusingavarietyofadvancedcompositetechniquesanditscompo n…     

磷酸对氯氧镁水泥性能的影响

实验分析了磷酸、磷酸与活性混合材复合使用对氯氧镁水泥性能的影响。实验结果表明,磷酸可以显提高氯氧镁水泥的抗水性,二元复合效果更佳,软化系数可达到1．0左右。     

Properties and interfacial microstructure of cement-based materials with composite micro-grains

Silica fume, fly ash and nano-fiber mineral materials （NR powder） are employed to incorporate into cement-based materials. According to the grain grading mathematical model of cement-based materials, two packing systems, namely, spherical grading system and nano-fiber reinforced system were designed. Properties and interfacial microstructure of the two systems were studied according to secondary interface theory. It was shown that nano-fiber mineral materials can improve the grain grading of the admixture, increase the density of the system, improve the microstructure of the interface and the hardened paste, and enhance the uniformity of cement-based materials mixed with composite micro-grains and greatly increase their wearable rigidity and flexure strength. In this paper, two kinds of interface models, including spherical grain model and nano-fiber reinforced interface model of the cement-based materials mixed with composite micro-grains, were brought forward.     

负压成型水泥基材料孔结构特征

为了研究低气压环境对水泥基材料引气性能的影响,采用负压模拟试验的方法,在不同的气压下测试引气剂溶液的发泡性能和气泡稳定性、引气水泥净浆的孔结构以及引气水泥砂浆的气孔结构.水泥净浆与水泥砂浆的试验样品均在设计气压下搅拌成型直至终凝硬化.试验结果表明:FC-1和FC-2两种新型引气剂溶液的泡沫相较三萜皂苷类引气剂(SJ-2...     

菱镁防火板改性的实验研究

研究了菱镁制品防止返卤泛霜的工艺和结构改性问题,采用正交试验优化菱镁水泥配比,同时加入微硅粉和粉煤灰及乳白胶等构成的复合改性剂,通过实验找出复合改性剂的最佳配方.复合改性剂中的高分子聚合物包覆在晶体外壁形成良好的防水保护层,提高了耐水性;扫描电子显微镜(SEM)观察微观结构表明,改性剂中的硅酸根在晶体间的空隙中自行交联一方面堵塞毛细孔道,抑制氯离子渗出而返卤泛霜,另一方面又能与Mg2+形成抗水性较强的胶凝结晶化合物,使菱镁制品返卤泛霜的现象得到了明显的抑制,同时也增加了制品强度和减小了翘曲变形性.