水泥泡沫混凝土的改性研究

采用丁苯乳液、苯丙乳液、硅灰、粉煤灰和橡胶粉等外加剂分别对物理发泡水泥混凝土的性能进行单一和复合改进试验。结果表明,复掺硅灰和丁苯乳液可显著提高泡沫混凝土早期强度,并降低吸水率,改善混凝土性能,当硅灰掺量4%,丁苯乳液掺量12%时,混凝土吸水率降低17%,7d抗压强度增加0.5 MPa;丁苯乳液对降低泡沫混凝土吸水率有一定促进作用;苯丙乳液对混凝土强度影响较大;硅灰与粉煤灰降低吸水率效果不佳;橡胶粉不能作为混凝土外加改性材料。     

早龄期复合胶凝材料的裂纹扩展阻力分析

研究了不同组成的复合胶凝材料硬化浆体(硅酸盐水泥,硅酸盐水泥 粉煤灰,硅酸盐水泥 矿渣,硅酸盐水泥 硅灰,硅酸盐水泥 硅灰 粉煤灰)早龄期时裂纹扩展阻力的发展,探讨了粉煤灰掺量对裂纹扩展阻力的影响.结果表明:早龄期时,在相同水胶比条件下,掺加硅灰使胶凝材料体系裂纹扩展阻力明显降低,在低水胶比条件下,掺加一定量的粉煤灰能够明显增加体系的裂纹扩展阻力,掺加20%的粉煤灰能使胶凝材料具有较高的裂纹扩展阻力.     

纳米二氧化硅对苯丙共聚物/水泥复合胶凝材料凝结硬化的影响

采用纳米二氧化硅作为调凝物质以期解决苯丙共聚物/水泥复合胶凝材料凝结硬化慢的问题。通过测定纳米二氧化硅改性苯丙共聚物/水泥复合胶凝材料的凝结时间及早期强度,分析纳米二氧化硅对复合胶凝材料凝结硬化过程的影响;采用等温量热法测定纳米二氧化硅改性苯丙共聚物/水泥的水化热,并采用X射线衍射仪对其水化产物进行表征;综合以上分析结果探讨纳米二氧化硅的作用机制。结果表明:掺入二氧化硅能有效促进复合胶凝材料的凝结硬化,二氧化硅掺量为1. 25%时促进作用最为显著;掺入纳米二氧化硅可促进铝酸三钙和硅酸三钙的水化,加快钙钒石和氢氧化钙的生成,缩短复合胶凝材料的水化诱导期和加速期,加快水泥水化进程,从而缩短凝结时间,提高早期强度。     

三元复合胶凝体系中硅灰和粉煤灰反应程度的确定

采用选择性溶解法和非蒸发水量法定量研究了不同龄期、不同掺量水泥-硅灰-粉煤灰三元复合胶凝体系中矿物掺合料的反应进程。用同细度同掺量的惰性石英粉替代粉煤灰以消除粉煤灰的稀释效应和异核成核效应,得到三元复合胶凝体系中硅灰的反应程度;根据三元复合胶凝体系中矿物掺合料的整体反应程度,计算了粉煤灰的反应程度。结果表明,硅灰的火山灰反应在复合胶凝体系水化1 d时就已经开始,并呈现早期快而后期慢的特点;而粉煤灰的火山灰效应,在7 d以后才开始并加快。在三元复合胶凝体系中,硅灰和粉煤灰的反应程度均随着粉煤灰掺量的提高而降低。     

调凝剂对物理发泡水泥性能的影响

采用物理发泡制备泡沫混凝土,以普通硅酸盐水泥为基材,为了让其凝结时间与泡沫的稳定时间相匹配,研究采用硫酸铝与快硬硫铝酸盐水泥作为调凝剂以调整普通硅酸盐水泥凝结时间。研究发现:随着调凝剂(Al2(SO4)3·18H2O和快硬硫铝酸盐水泥)掺量的逐渐增加,普通硅酸盐水泥净浆凝结时间逐渐缩短,泡沫混凝土容重呈降低趋势,并且气孔尺寸逐渐减小;调凝剂的掺加会提高低容重(425Kg/m3)泡沫混凝土的早期强度,而使其后期(28d)强度有所降低;但是,随着调凝剂掺量的逐渐增加,高容重(725Kg/m3)泡沫混凝土的抗压强度逐渐降低;并用XRD方法对其水化产物进行表征,并分析了调凝剂促凝和后期强度降低的原因。结果表明:在低容重泡沫混凝土的制备过程中可以适当掺加调凝剂,而在高容重泡沫混凝土的制备过程中应避免调凝剂的使用。     

复合促凝剂对物理法超轻泡沫混凝土性能的影响研究?

为制备低成本、防火、保温隔热性能优异的无机保温隔热材料,以复合促凝剂改性的普通硅酸盐水泥为胶凝材料,采用物理法制备了超轻泡沫混凝土(孔隙率＞90％),结合图像分析、SEM及 XRD对硬化试样的气孔结构及组成进行了表征,并研究了复合促凝剂对新拌超轻泡沫混凝土工作性、硬化超轻泡沫混凝土气孔结构、抗压强度及导热系数的影响.研究表明,复合促凝剂掺量增加,新拌超轻泡沫混凝土相对粘度与相对极限剪切应力变大,流动度减小,硬化试样中小于0．2 mm 气孔比例增加,D50变小,气孔孔径均匀程度与保温隔热性能改善,力学性能先提升后略有降低;复合促凝剂掺量为4％,硬化试样的干密度为175．2 kg/m3,7D、28D 抗压强度分别为0．25和0．33 MPa,导热系数为0．0516 W/(m·K).     

矿物外加剂对丁苯聚合物/水泥复合胶凝材料凝结硬化过程的影响及机制

为了比较沸石、纳米二氧化硅和稻壳灰这3种矿物外加剂对丁苯聚合物/水泥复合胶凝材料凝结硬化过程作用的差异,分别采用这3种矿物外加剂为调凝材料,并从凝结时间、早期强度、水化进程以及水化产物等角度比较3种矿物外加剂对丁苯聚合物/水泥复合胶凝材料的影响。结果表明,3种矿物外加剂都能促进复合胶凝材料的凝结硬化,大幅缩短凝结时间,提高早期强度。但3种矿物外加剂的调凝效果互不相同,调凝机理也有差异:沸石对AFt的生成有较大的促进作用,它不仅能促进C3A的水化,自身也能与Ca(OH)_2反应生成AFt和CSH凝胶;而纳米二氧化硅和稻壳灰对C3S水化的促进作用较强,自身也会与Ca(OH)_2反应生成CSH凝胶。     

普通硅酸盐-硫铝酸盐水泥复合凝胶体系的制备及性能研究

根据设计配比,制备了普通硅酸盐-硫铝酸盐水泥复合凝胶体系。通过改变普通硅酸盐水泥和硫铝酸盐水泥的质量比、水胶比和减水剂用量等参数,采用净浆流动度、凝胶时间、结石率、抗压强度和竖向膨胀率等实验,探究了普通硅酸盐-硫铝酸盐水泥复合凝胶体系的性能影响因素。结果表明,当硫铝酸盐水泥的用量为70%(质量分数)、水胶比为0.5、减水剂用量为0.5‰(质量分数)时,复合胶凝体系的流动度最大,达320 mm,可注性好;其初凝和终凝时间分别为6和14 min,凝胶时间短;其结石率为100%,28 d竖向膨胀率约为0.14%,无需二次注浆;其28 d抗压强度为43 MPa,加固强度高。适量的硅灰和硅渣的掺杂可以提高复合胶凝体系后期的抗压强度、抗折强度和流动度,当硅灰掺量为10%(质量分数)时,复合胶凝体系3和28 d的抗压强度、抗折强度出现了峰值;当硅渣掺量为15%(质量分数)时,复合胶凝体系28 d的抗压强度和抗折强度达到最高;当硅渣掺量为10%(质量分数)时,复合胶凝体系流动度达到334 mm。     

基于活性粉末混凝土的水泥相容性实验研究

通过水泥相容性试验,确定了合适的减水剂和硅灰品种,考察了水胶比和硅灰掺量对胶凝材料流动性的影响,研究了水胶比、粉煤灰、硅灰、石英粉、纳米硅等对RPC流动性的影响规律。实验结果表明,采用适当比例的硅灰、粉煤灰和纳米硅,可以提高RPC的流动性,RPC中加入缓凝剂,延缓了拌合物的凝结时间,有利于提高RPC的强度。特别是纳米硅的加入,明显的改善了RPC的流动性。     

弱碱环境下硅灰复合硅酸盐胶凝材料体系硫酸盐侵蚀产物

研究了硅灰替代量(质量分数)为0%、5%、10%的复合硅酸盐胶凝体系浸泡在弱碱环境下,10%(质量分数)Na_2SO_4溶液中侵蚀210d时的侵蚀产物和含量。利用XRD、SEM、EDS对侵蚀产物进行了表征,通过K值法定量计算了硅灰复合硅酸盐胶凝体系中石膏的含量,通过分光光度法对硅灰复合硅酸盐胶凝体系中自由硫酸根离子以及总硫酸根离子含量进行了测定。结果表明,在弱碱环境下,10%Na_2SO_4溶液中硅灰复合硅酸盐胶凝体系的主要侵蚀产物是石膏和钙矾石,侵蚀产物的形成引起膨胀开裂,且随硅灰掺量的增加,硅灰复合硅酸盐胶凝体系中的自由硫酸根离子及总硫酸根离子含量和侵蚀产物明显减少,膨胀率也随硅灰掺量的增加而减小,硅灰对复合硅酸盐胶凝体系的膨胀有一定的改善作用。     

凝固科学技术与材料

从凝固科学与实践发展的角度介绍了当前凝固材料体系的基本框架和凝固科学主要发展阶段的基本理论。作为材料科学与工程的基本组成，凝固科学技术正在现代科学理论的基础上针对传统材料的改性提高和新材料的发展需求，以控形、控构、控性为目标开展优质铸件的定向、晶体生长、快凝、深过冷及各种新型和超常领域凝固过程的研究，并介绍了其中某些方面和展望了可能的发展趋势。     

Creation and motion of dislocations and fracture in metal and silicon crystals

By making a step on one surface ( ) of a rectangular small paralellepiped copper crystal, dislocations could be created by the molecular dynamic method. The dislocation created was not a complete edge dislocation but a pair of Heidenreich-Shockley partial dislocations. Each time a dislocation was created, the stress on the surface was released. Small copper crystals having a notch were pulled (until fracture), compressed and buckled by use of the molecular dynamic method. An embedded atom potential was used to represent the interaction between atoms. Dislocations were created near the tip of the notch. A very sharp yield stress was observed. The results of high speed deformations of pure silicon small crystals using the molecular dynamics are presented. The results suggest that plastic deformation may be possible for the silicon with a high speed deformation even at room temperature. Another small size single crystal, the same size and the same surfaces, was compressed using molecular dynamic method. The surfaces are {110}, {112} and {111}. The compressed direction was [111]. It was found that silicon crystals are possible to be compressed with a high speed deformation. This may suggest that silicon may be plastically deformed with high speed deformation.     

江澳两地高校文创设计的协同研究与商业实践

目的 探索江门世遗文化的传承、发展和转化的新思路,践行国家在《粤港澳大湾区发展规划》纲要中要求江门承担与港澳地区文化创意合作与开发任务的分工。方法 与澳门高校紧密合作,开展专业培训课程,以开平碉楼为例,从人文视角开展设计研究,梳理开平碉楼的文化脉络,把世遗文化的元素和其背后的文化融入文创产品中,提升文创产品的附加值,推动当地文创产业结构的变革。结果 两地高校构建了稳定的科研团队,开设长期有效的设计培训课程,与景区建立了研究协作关系,帮助景区构建了一套产销研的商业模式。结论 以跨区域高校合作为平台,以文创产品为抓手,依托江澳两地的资源优势,可以构建江门世遗文化全新的品牌形象,最终推动开平世遗文化的活化。     

Development and challenges of planning and scheduling for petroleum and petrochemical production

Production planning and scheduling are becoming the core of production management, which support the decision of a petrochemical company. The optimization of production planning and scheduling is attempted by every refinery because it gains additional profit and stabilizes the daily production. The optimization problem considered in industry and academic research is of different levels of realism and complexity, thus increasing the gap. Operation research with mathematical programming is a conventional approach used to address the planning and scheduling problem. Additionally, modeling the processes, objectives, and constraints and developing the optimization algorithms are significant for industry and research. This paper introduces the perspective of production planning and scheduling from the development viewpoint.     

甲壳素与壳聚糖的改性及应用

甲壳素、壳聚糖及其衍生物是一种天然高分子,随着对其研究的深入发展,涉及的内容和应用范围越来越广泛.概述了甲壳素、壳聚糖的结构、性质及其化学改性和共混改性的方法,简单介绍了它们的应用领域.     

ATP-Responsive and ATP-Fueled Self-Assembling Systems and Materials

Adenosine triphosphate (ATP) is a central metabolite that plays an indispensable role in various cellular processes, from energy supply to cell-to-cell signaling. Nature has developed sophisticated strategies to use the energy stored in ATP for many metabolic and non-equilibrium processes, and to sense and bind ATP for biological signaling. The variations in the ATP concentrations from one organelle to another, from extracellular to intracellular environments, and from normal cells to cancer cells are one motivation for designing ATP-triggered and ATP-fueled systems and materials, because they show great potential for applications in biological systems by using ATP as a trigger or chemical fuel. Over the last decade, ATP has been emerging as an attractive co-assembling component for man-made stimuli-responsive as well as for fuel-driven active systems and materials. Herein, current advances and emerging concepts for ATP-triggered and ATP-fueled self-assemblies and materials are discussed, shedding light on applications and highlighting future developments. By bringing together concepts of different domains, that is from supramolecular chemistry to DNA nanoscience, from equilibrium to non-equilibrium self-assembly, and from fundamental sciences to applications, the aim is to cross-fertilize current approaches with the ultimate aim to bring synthetic ATP-dependent systems closer to living systems.     

The Candela and Photometric and Radiometric Measurements

The national measurement system for photometric and radiometric quantities is presently based upon techniques that make these quantities traceable to a high-accuracy cryogenic radiometer. The redefinition of the candela in 1979 provided the opportunity for national measurement laboratories to base their photometric measurements on optical detector technology rather than on the emission from high-temperature blackbody optical sources. The ensuing technical developments of the past 20 years, including the significant improvements in cryogenic radiometer performance, have provided the opportunity to place the fundamental maintenance of photometric quantities upon absolute detector based technology as was allowed by the 1979 redefinition. Additionally, the development of improved photodetectors has had a significant impact on the methodology in most of the radiometric measurement areas. This paper will review the status of the NIST implementation of the technical changes mandated by the 1979 redefinition of the candela and its effect upon the maintenance and dissemination of optical radiation measurements.     

PSD和PWELCH函数的分析改进及应用

针对MATLAB中两个内建功率谱密度计算函数psd()和pwelch()计算结果迥异的现象,在功率谱密度估计理论的基础上,根据经典的周期图理论和Welch平均周期图方法,通过详细分析源程序,解析计算方法,发现psd()计算的并不是工程单边功率谱密度,而是采样信号双边谱,故与pwelch()结果迥异,另外pwelch()不能对分段信号数据进行预处理。就上述不足提出了相应的改进措施,比较验证表明改进措施行之有效。