不同种类石膏对水泥使用性能的影响不同.结合不同种类石膏的溶解特性分析了石膏对水泥凝结时间、强度、与减水剂的相容性等性能的影响以及延迟性钙钒石生成的风险,认为应根据实际要求选择石膏类型以发挥石膏的作用,同时建议有必要对硬石膏可能引起延迟性钙钒石、煅烧石膏与减水剂相容性以及化工石膏中杂质限值和处理等问题进行深入研究.

关键词：石膏；性能；相容性；延迟性钙钒石

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以氨水作为沉淀剂并控制溶液的pH值,采用Fe3+和Fe2+共沉淀法制得了磁性四氧化三铁纳米颗粒.合成的磁性纳米颗粒通过高分辨透射电镜、X射线衍射仪、傅里叶变换红外光谱仪进行了表征.四氧化三铁纳米颗粒的粒径约为10nm,其表面含有丰富的羟基.为了增强磁性四氧化三铁纳米颗粒和聚合物基质之间的相互作用,在纳米颗粒的表面接枝上乙烯基单体.傅里叶变换红外光谱仪和热重分析仪的测试结果显示,聚合物链共价结合在纳米颗粒表面.表面接枝聚合后,四氧化三铁纳米颗粒由极性转变为非极性.

关键词：磁性；四氧化三铁；纳米颗粒；接枝聚合；表面修饰；苯乙烯；甲基丙烯酸甲酯

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纳米结构的ZnO由于具有优异的光、电、磁、声等性能,已经成为光电、化学、催化、压电等领域中聚焦的研究热点之一.不同纳米结构的ZnO其制备方法不同,着重概述了采用化学气相沉积(CVD)工艺制备ZnO纳米材料,包括直接热分解、高温加热锌粉、碳热还原法以及金属有机气相沉积(MOCVD)4种方法,重点讨论了不同锌源和氧源对ZnO纳米结构的影响规律,并初步探讨了ZnO的VLS与VS生长机理,同时展望了ZnO在各领域中的最新应用.

关键词：ZnO纳米结构；CVD法；生成机理；应用

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Marine composites are materials used in the construction of off-shore structures and boat components to increase performance, decrease fuel consumption, and significantly reduce carbon dioxide emissions. They are often used as alternatives to traditional materials such as aluminum and steel. Composites such as glass fiber-reinforced plastics and CFRP are currently being widely used in the manufacture of boats and other marine vessels. Marine composites are also used in subsea applications as protection structures for subsea wellheads and valves.

关键词：船用复合材料；二氧化碳；玻璃纤维

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A recent rise in asphalt binder prices has led state agencies and contractors to use higher quantities of Reclaimed Asphalt Pavement (RAP). Besides being economic, sustainable, and environmentally friendly, RAP can be replaced for a portion of aggregates in Hot Mix Asphalt (HMA) where quality aggregates are scarce. In this project, the effect of increasing RAP percentage and using fractionated RAP (FRAP) in HMA mixture on moisture resistance, rutting, and fatigue cracking were evaluated. Mixtures with five different RAP and FRAP contents (20, 30, and 40RAP, and 30and 40FRAP) were studied. The Hamburg Wheel Tracking Device (HWTD) Test (TEX-242-F), Kansas Standard Test Method KT-56 or modified Lottman Test, and Dynamic Modulus Test (AASHTO TP: 62-03) were used to predict moisture damage, rutting potential and fatigue cracking resistance of the mixes. HMA specimens were prepared based on Superpave HMA mix design criteria for 12.5 mm (1/2 inch) Nominal Maximum Aggregate Size (NMAS) and compacted using the Superpave gyratory compactor. Results of these tests showed that although mixture performance in the laboratory tests declined as the percentage of RAP increased in the mix, even mixtures with 40RAP passed the minimum requirements in commonly used tests.

关键词：修复计划；沥青；高速公路

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Highway agencies continuously strive to expedite pavement construction and repairs and to evaluate materials and methods to provide long-lasting pavements. As part of this effort, agencies have used precast concrete slabs for more than 10 years with successive improvements in processes and systems. The Virginia Department of Transportation recently used two precast systems along with conventional cast-in-place repairs on a section of jointed reinforced concrete pavement on I-66 near Washington, D.C. One precast system, precast concrete pavement (PCP), used doweled joints. The other precast system, prestressed precast concrete pavement (PPCP), used transversely prestressed slabs post-tensioned in the longitudinal direction. Both precast systems are performing satisfactorily after 1.5 years of traffic, and the contractor was satisfied with the constructability. In multiple locations, transverse expansion joints in PPCP were observed to be wider than the 12-in width specified; excessively wide joints often compromise joint sealant performance, and erosion from water flowing through such joints may result in eventual loss of support over time. There were a few cracks in the PPCP section, originating mainly from grouting holes, cracks in the block-out patches, cracks and loss of epoxy at lifting hook holes, and corner breaks. There were some mid-slab cracks in the PCP slabs immediately after opening to traffic, but they are still tight and stable after 1.5 years of traffic. Even though the precast slabs initially cost more than the cast-in-place repairs to construct, the ability to construct the pavement within a short period of lane closure per day and the probability of improved quality control of plant-cast concrete warrant their use. Since this was the first application in Virginia, certain issues occurred and most were overcome, such as matching of slabs and grout leakage. The project was successfully completed and further implementation is recommended.

关键词：路面；预制系统；混凝土；质量控制

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Roofing is the process of covering the uppermost surface and supporting structures of a building with materials such as shingles, membranes, insulating glass, and cement. There are two main types of roofing defined by the pitch or slope of the roof: Steep-slope Roofing and Low-sloped or Flat Roofing. The roofing systems are mainly chosen based on the climatic conditions of the region. Proper roofing provides strength to the building structure and also mitigates the overall cost of maintaining the room temperature by avoiding the cost of air.

关键词：屋顶；支承建筑物；建筑材料；玻璃；水泥

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Antibacterial glass inhibits the multiplication of bacteria and fungi and is equipped with the capacity to kill 99.9 percent of the bacteria on its surface. This type of glass is suitable for structures in which hygiene requirements have high priority. They are used in various applications in hospitals, laboratories, spas, swimming pools, sports halls, nursing homes, bathrooms, dining rooms, chemists' shops, and others. Most vendors use silver, copper, zinc, and titanium amongst other metals, in the manufacturing of antibacterial glass. Antibacterial glass can also prevent the growth of bacteria such as Methicillin-Resistant Staphylococcus Aureus, which is resistant to certain antibiotics. They are also very effective against HAIs.

关键词：抗菌玻璃；抑制；细菌真菌；繁殖；结构

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TiB2/Al复合材料在结构、耐磨、航空航天领域有着广阔的应用前景.然而,不同制备工艺制备的材料在微观结构和性能方面都存在不同,其对应的生成机制也不尽相同.概述了不同工艺制备TiB2颗粒的生成机制.由于混合盐反应法具有易操作、低成本、易连续化生产等特性,因此重点探讨了其反应机理及存在的问题.针对增强相TiB2颗粒微小表面自由能大、容易聚集形成链条状、造成材料的脆性等缺点,给出了几种改善工艺.

关键词：铸造；金属基复合材料；颗粒增强；显微组织；热分析

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从原材料、生产工艺、颗粒形貌特征和性能方面将膨胀玻化微珠与传统膨胀珍珠岩做了系统对比分析,并综述和分析了玻化微珠掺量变化对水泥砂浆和混凝土性能影响的相关研究成果,指出了当前膨胀玻化微珠及其应用于水泥基材料中应着重加强的一些关键基础和技术研究.

关键词：膨胀玻化微珠；膨胀珍珠岩；水泥基材料；抗压强度；导热系数；弹性模量

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