Optimization of SO<Subscript>3</Subscript> content in blended cementitious materials

Experimental investigation was conducted on the effects of gypsum types and SO₃ content on the fluidity and strengths of different cementitious systems. The experimental results show that influences of gypsum in various cementitious materials are different. For cementitious materials blended with various proportions of slag-fly ash and 5% gypsum content, influences of gypsum and calcined gypsum on the fluidity and flexural/compressive strength are similar. It is revealed that “combination effect” and “synergistic effect” of slag and fly ash play an important role during hydration. For cementitious materials with 45% clinkers, 30% slag, 20% fly ash and 5% limestone, the optimized SO₃ contents in gypsum and calcined gypsum are 3.13% and 3.51% respectively and the optimized gypsum content is 6.5%. While both of them are blended, the optimum ratio of gypsum to calcined gypsum is 40%:60% (total gypsum content 6.5%), correspondingly the optimum ratio of SO₃ is 19.3%:32. 4%. CHEN Mei-zhu : Born in 1974 Funded by Hubei Bureau of Science and Technology of China (981P0202)     

环保型胶凝材料的制备及其力学性能研究

利用硅酸盐水泥熟料、矿渣、粉煤灰、硅灰、石膏及其他组分制备出环保型胶凝材料Ⅰ和Ⅱ,并测试了其性能。结果表明,环保型胶凝材料的硅酸盐水泥熟料掺量(30%～50%),具有较低的需水量和正常的凝结时间,其标准稠度需水量为23%,净浆和配制的混凝土都具有较高的流动性,且有较小的流动性经时损失,标准养护28天的胶砂试件抗压强度可以达到50MPa以上,可以配制出C50 C60高流态的高性能混凝土.     

Mechanical properties of gangue-containing aluminosilicate based cementitious materials

High performance aluminosilicate based cementitious materials were produced using calcined gangue as one of the major raw materials. The gangue was calcined at 500℃. The main constituent was calcined gangue, fly ash and slag, while alkali-silicate solutions were used as the diagenetic agent. The structure of gangue-containing aluminosilicate based cementitious materials was studied by the methods of IR, NMR and SEM. The results show that the mechanical properties are affected by the mass ratio between the gangue, slag and fly ash, the kind of activator and additional salt. For 28-day curing time, the compressive strength of the sample with a mass proportion of 2：1：1 （gangue： slag： fly ash） is 58.9 MPa, while the compressive strength of the sample containing 80wt% gangue can still be up to 52.3 MPa. The larger K^＋ favors the formation of large silicate oligomers with which AI（OH）4- prefers to bind. Therefore, in Na-K compounding activator solutions more oligomers exist which result in a stronger compressive strength of aluminosilicate-based cementitious materials than in the case of Na-containing activator. The reasons for this were found through IR and NMR analysis. Glauber＇s salt reduces the 3-day compressive strength of the paste, but increases its 7-day and 28-day compressive strengths.     

机械粉磨对岩土固化用无熟料胶凝材料性能的影响

利用稻壳灰、CFB脱硫灰、钢渣协同制备一种无熟料水硬性无机胶凝材料,可替代水泥用于岩土固化。为提高这种胶凝材料的活性及其他性能,研究经机械粉磨后胶凝材料的性能变化及其机理。结果表明：随着粉磨时间增加,胶凝材料的粒度分布曲线由多峰分布转变为单峰分布,标准稠度用水量减少,凝结时间缩短;水化诱导期的结束时间和第2放热峰出现时间明显提前,累积放热量增加;砂浆试件的早期抗压强度和自收缩显著增加;采用无熟料胶凝材料制备流态固化土,其初始流动扩展度随粉磨时间增加而增加,经时损失加快;机械粉磨对固化土的早期强度影响不显著,后期强度则呈现先增加后降低的趋势。采用该无熟料胶凝材料制备流态固化土,能满足一般回填工程的强度要求。     

Effect of quaternary ammonium salts on flotation behavior of aluminosilicate minerals

The electrokinetic properties and flotation of diaspore,kaolinite,pyrophyllite and illite with quaternary ammonium salts collectors were studied.The results of flotation tests show that the collecting ability of quaternary ammonium salts for the four minerals is in the order(from strong to weak)of octadecyl dimethyl benzyl ammonium chloride(ODBA),cetyl trimethyl ammonium bromide(CTAB),dodecyl trimethyl ammonium chloride(DTAC).Under the condition of alkalescence,it is possible to separate the diaspore from the silicate minerals such as kaolinite,illite and pyrophyllite using quaternary ammonium salts as collector.Isoelectric points(IEP)of diaspore,kaolinite,pyrophyllite and illite are pH=6.0,3.4,2.3 and 3.2,respectively.Quaternary ammonium salts can change ζ-potential of the aluminosilicate minerals obviously.The flotation mechanisms were explained by ζ-potential and Fourier transform infrared spectrum(FT-IR)measurements.The results demonstrate that only electrostatic interaction takes place between aluminosilicate     

考虑界面过渡区及集料因素的水泥基材料碳化模型

集料和界面过渡区对水泥基材料抗碳化性能有显著影响。基于Fick第二定律,提出一种考虑集料和界面过渡区影响的CO₂扩散模型,模型中首次引入界面过渡区的扩散系数并给出相应参数的计算方法,并基于质量守恒定律给出CO₂反应模型,利用该模型研究荷载作用下C30和C50混凝土中CO₂的浓度分布。结果表明,考虑集料和界面过渡区影响能更准确地计算CO₂在水泥基材料中的扩散系数及碳化深度值。通过与文献中的试验数据进行比较,进一步验证了理论模型的可靠性。模型将集料和界面过渡区作为评价混凝土耐久性的重要因素,为钢筋混凝土结构的设计和寿命预测提供依据。     

Relationship between polymerization degree and cementitious activity of iron ore tailings

The aim of this study is to understand the relationship between the polymerization degree and cementitious activity of iron ore tailings.In light of the poor usage of iron ore tailings,stockpile samples from Tangshan were studied in terms of their ability to become cementitious materials.Compound thermal activation was used to improve the cementitious properties of the tailings,while analyzing methods,such as X-ray diffraction (XRD),infrared spectroscopy (IR),nuclear magnetic resonance (NMR),and X-ray photo...     

Iron ore tailings used for the preparation of cementitious material by compound thermal activation

In the background of little reuse and large stockpile for iron ore railings, iron ore tailing from Chinese Tonghua were used as raw material to prepare cementitious materials. Cementitious properties of the iron ore tailings activated by compound thermal ac-tivation were studied. Testing methods, such as XRD, TG-DTA, and IR were used for researching the phase and structure variety of the iron ore tailings in the process of compound thermal activation. The results reveal that a new cementitious material that contains 30wt% of the iron ore tailings can be obtained by compounded thermal activation, whose mortar strength can come up to the stan-dard of 42.5 cement of China.     

高钙粉煤灰作为添加剂制备赤泥偏高岭土胶凝材料

采用XRD、IR、SEM、和EDS等分析手段,研究了高钙粉煤灰作为添加剂制备的赤泥偏高岭土胶凝材料的力学性能和水化产物.结果表明:合适掺量的高钙粉煤灰(<14%)有助于试样力学性能的提高;高钙粉煤灰作为添加剂所制备的赤泥偏高岭土胶凝材料,其水化产物主要有水化硅酸铝钙、沸石相、羟基硅酸铝、钙长石、蓝晶石、水化硅酸钙和叙永石. 随着试样养护龄期的增长胶凝材料结构更密实,形成PSS型结构.     

微胶囊对水泥自修复复合材料微观结构的影响

在环氧树脂微胶囊的制备实验基础上,制备水泥自修复复合材料,研究养护龄期和微胶囊掺量对水泥自修复复合材料微观结构的影响,采用多种测试仪器对复合材料孔结构特性、电性能、抗渗透性能和水化热进行了分析.结果表明,随着养护龄期的增加,复合材料电阻值显著增大,而累积孔体积和吸水性系数减小;随着微胶囊掺量的增加,电阻值增大,而累积孔体积、吸附量与脱附量、吸水性系数以及水化放热速率与放热量减小.     

基于汽轮机常规性能试验测点布置的局部定量分析模型

汽轮机常规性能试验测点集中安装在与热耗指标计算相关的位置上,由于测点有限,在进行机组能耗指标定量分析计算时,现行分析方法需要使用部分机组运行监控仪表,影响了计算结果的精确度。通过引入加热单元和虚拟热力系统的概念,构建了相关数学模型,实现了利用试验测点数据,对试验测点齐全、且是机组能损分布重点区域的高加系统内典型扰动进行定量分析。模型具有通用、精确、适宜于汽轮机常规性能试验数据定量分析使用的特点。     

绿色韧性水泥基复合材料力学性能

为了研究绿色尾矿砂PVA纤维增强水泥基复合材料的韧性,参考国内外试验方法开展了立方体抗压、薄板拉伸和冲击韧性等力学性能试验研究.分析了纤维与基体的相互作用及增韧机理,讨论了纤维掺量和水胶比二元因素对增韧性能的影响.该研究获得了复合材料相应的强度和韧性指标,为高性能尾矿砂PVA纤维增强水泥基复合材料的制备和工程应用提供了参考.     

气相色谱法定量测定茉莉醛

对气相色谱法定量测定茉莉醛进行了研究，得到一种快速、简便、准确测定茉莉醛含量的方法。     

绿色韧性水泥基复合材料碳化性能试验

为了研究绿色韧性水泥基复合材料(GCC)的耐久性,进行了快速碳化试验,研究了GCC的抗碳化性能以及水胶比和纤维掺量对抗碳化性能的影响规律.结果表明:随着碳化时间的增加,GCC的碳化深度逐渐增加,但其碳化速率逐渐减小;掺加一定量的纤维可以改善GCC的抗碳化性能,但当纤维掺量超过一定临界值时,GCC的抗碳化性能反而有所降低;水胶比对于GCC的抗碳化性能有明显影响,随着水胶比的增加,GCC材料的抗碳化性能逐渐降低.     

HPLC法测定番茄红素胶囊中番茄红素的含量

建立了用HPLC法测定番茄红素含量的分析方法,采用ODS色谱柱（150mm×4.6mm,5μm）,流动相为乙腈-甲醇-二氯甲烷（60∶25∶15）,检测波长472nm,柱温32℃。试验结果表明,番茄红素在0.2-40μg/mL范围内线性关系良好（r=0.9996）,加标回收率大于96.0%,并可同时分离番茄红素和共存的β-胡萝卜素。该方法准确、可靠,适用于番茄红素胶囊中番茄红素的含量测定。     

三元四元简单水盐体系相图的自动分析及绘制

通过分析水盐体系中自由度及相图中点与线的关系,研究了能够自动分析相图中点与线的算法.此算法能利用相图数据点上的液相离子组成和平衡固相分析出点的类型及点之间的连线关系.并基于此算法开发了相图绘制程序,此程序能够自动分析并绘制三元和四元简单体系的等温相图.     

Thermoelectric properties of quaternary Mg_2Sn_(0.4)Si_(0.6-x)Ge_x alloys

Quaternary alloys Mg2Sn0.4Si0.6-xGex(x=0,0.02,0.05,0.08 0.1,and 0.2) were prepared using induction melting followed by hot-pressing.Relative densities of the sintered samples were over 97% of the theoretical values.Multiple phases were detected in the samples.It was found that the Seebeck coefficient was sensitive to the content of Mg2Ge and a maximum value of about 350 μV·K-1 was obtained.The introduction of Ge increases the electrical conductivity and the thermal conductivity simultaneously.The mechanism ...     

量化分析珍珠岩粉在水泥基材料中的火山灰效应

为了量化地分析珍珠岩粉在水泥基材料中的火山灰效应,以判定珍珠岩磨细粉用作水泥基材料的掺合料之优劣,采用以抗压强度构成为基础的火山灰效应定量指标,研究其在水泥砂浆和混凝土中随珍珠岩粉掺量、细度及养护方式、龄期和配合比的变化特征,结果表明:经蒸压处理的混凝土即使珍珠岩粉掺量达到20％～60％(质量分数)其抗压强度也可与未掺的基准样品基本一致;对混凝土强度的绝对值而言掺合料的最佳掺量为15％(质量分数),此时混凝土强度最高;其它火山灰效应参数如R_aR_pC_p在所讨论范围内大体随着掺量增加而提高,由此研判珍珠岩磨细粉可作为水泥基材料中替代水泥的辅助胶凝材料;同时反映一种掺合料在不同的水泥基材料或养护环境中火山灰效应的差异性,为选择使用掺合料提供最佳参数依据。     

Theoretical analysis on bending behavior of functionally graded composite beam crack-controlled by ultrahigh toughness cementitious composites

Ultrahigh toughness cementitious composites (UHTCC) obviously show strain hardening property under tensile or bending loading. The failure pattern of the UHTCC components exhibits multiple fine cracks under uniaxial tensile loading with prominent tensile strain capacity in excess of 3%, with merely 60 μm average crack width even corresponding to the ultimate tensile strain state. The approach adopted is based on the concept of functionally-graded concrete, where part of the concrete, which surrounds the main longitudinal reinforcement in a RC (reinforced concrete) member, is strategically replaced with UHTCC with excellent crack-controlling ability. Investigations on bending behavior of functionally-graded composite beam crack controlled by UHTCC has been carried out, including theo- retical analysis, experimental research on long composite beams without web reinforcement, validation and comparison between experimental and theoretical results, and analysis on crack control. In addition to improving bearing capacity, the results indicate that functionally-graded composite beams using UHTCC has been found to be very effective in preventing corrosion-induced damage compared with RC beams. Therefore, durability and service life of the structure could be enhanced. This paper discusses the development of internal force and crack propagation during loading process, and presents analysis of the internal force in different stages, moment-curvature relationship from loading to damage and calculation of mid-span deflection and ductility index. In the end, the theoretical formulae have been validated by experimental results.     

侧风对冷却塔性能影响的特异性定量分析方法

基于换热平衡方程和空气动力方程的耦合关系,建立无侧风条件下,自然通风湿式冷却塔的热力性能计算模型,并利用MATLAB程序,通过迭代运算方法,对两方程进行联立求解,从而获得与现场测试相同的气象和运行条件下,剔除侧风影响后冷却塔通风量和冷却数的应达值,然后结合现场测试得到的实际通风量和冷却数,提出了可以特异地反映侧风对冷却塔性能影响的新指标。某3500m2冷却塔的计算结果表明,在模型散热量和实测散热量相同的条件下,侧风影响会使得冷却塔的通风量最大减少38.5％,此时体积分数为33.9％的填料没有得到有效利用,侧风还会增加冷却塔的冷却任务,相应的,需要冷却塔具有更好的冷却性能,这对于了解侧风对冷却塔性能的影响以及指导冷却塔的设计与改造有重要意义。