纳米TiO2光催化功能建筑材料研究进展

以纳米TiO2为代表的纳米半导体光催化材料是目前各国科学家研究的热点.将纳米TiO2与涂料、玻璃、水泥和陶瓷等建材结合使建筑材料具有光催化功能,实现了其对表面污染物的处理及自清洁,具有很大的研究和应用价值.介绍了纳米TiO2光催化涂料、自清洁玻璃、光催化水泥混凝土和光催化功能陶瓷等的研究进展,对目前面临的问题提出了相关...     

建筑节能中调湿材料的应用及研究进展

从节能减排角度说明了调湿材料在建筑节能上的应用意义,系统介绍了调湿材料的作用原理、性能评价指标及分类,重点论述了国内外各类调湿材料特别是复合调湿材料的最新研究进展,并提出了调湿材料的发展趋势与研究方向。     

Radioactivity in building materials in Iraq

Activity concentrations of (226)Ra, (232)Th and (40)K in 45 samples of different building materials used in Iraq were measured using gamma-spectroscopy system based on high-purity germanium detector with an efficiency of 40 %. Radium equivalent activity, air-absorbed dose rate, annual effective dose, external and internal hazard indices and alpha index due to radon inhalation originating from building materials were measured to assess the potential radiological hazard associated with these building materials. The activity concentrations of the natural radionuclides (226)Ra, (232)Th and 40K were found to range from below detection limit (BDL) to 223.7 ± 9, BDL to 93.0 ± 3 and BDL to 343.1 ± 12, respectively. Values of average radium equivalent activity, air-absorbed dose rate, indoor and outdoor annual effective doses, external and internal hazard indices and alpha index ranged from 6.5 to 124.9, 16.2 to 89.5 (nGy h(-1)), 0.08 to 0.44 mSv, 0.02-0.11 mSv, 0.09 to 0.53, 0.13 to 0.69 and 0.03 to 0.62, respectively. These values indicate a low dose. Therefore, the building materials used in the current study are quite safe to be used as building materials.     

Trends in corrosion protection of materials

The rapid advances in technologies in various fields have also recorded significant progresses in the field of newer materials as the reliability and effective performance of industrial equipment as well as the associated components mostly depend upon their integrity over specified period. Though the basic methods of protection of materials like use of corrosion-resistant alloys, application of surface coatings, modification of the environment and application of cathodic protection have largely remained the same, the approaches and techniques adopted in each of these fields have been so advanced that one could today advocate appropriate protection systems with high reliability and performance. The author presents some of his contributions along with his colleagues in the fields of cathodic protection of vital structures, development of newer coatings for specific applications and new approaches to corrosion monitoring techniques, besides highlighting the corrosion behaviour of some of the heat-treated alloys which are specifically used in such strategic areas as space and defence. The presentation would also cover briefly some of the techniques that have been employed by the author for better understanding of corrosion and passivation of metals and alloys.     

Trends in radar absorbing materials technology

The research in the area of Radar Absorbing Materials (RAMs) has been actively pursued for at least four decades. Although resonant RAMs were originally designed by transmission line approach, and the broad band RAMs were obtained by multilayering, the quest for ultrawide band performance has led to novel approaches such as chirality and even exploring biochemical products. It is observed that radome materials are frequently used as RAMs. The understanding of the underlying principles of electromagnetic analysis and design, fabrication and the trends in RAMs reviewed in this paper could lead to indigenisation, and even pioneering next generation of RAM technology.     

Radiocesium interception potentials in building materials

The radiocesium interception potentials [RIP(K)] in powders of building materials, mmol kg^?1, determined by the Wauters method, are as follows: brick 10–15, limestone 12, concrete 70–190, granite 40–200, and asphalt 140–280. The RIP(N) values, mmol kg^?1, are lower than the respective RIP(K) values: limestone 2, brick 2–5, granite 3–11, asphalt 21–30, and concrete 45–195. For concrete and brick, the selectivity coefficients K _c(K/N) on ¹³⁷Cs-selective sorption sites vary from 1.5 to 2.8, and for asphalt, limestone, and granite they reach 7–18, which suggests the presence of illite and mica particles affecting the ¹³⁷Cs sorption in these materials. The values of K _d of ¹³⁷Cs, calculated from the RIP(K) values and from the predicted concentrations of K⁺ in the pore solution of intact building materials, dm³ kg^?1, are as follows: brick, limestone, and granite, 5–26; asphalt, 190–390; concrete, 600–1700.     

Durability of building materials: Durability research in the United States and the influence of RILEM on durability research

This paper is based on the text of a talk given at a RILEM Seminar on Durability of Building Materials. It reviews some of the recent non-proprietary research on the durability of building materials carried out in the US. It also reviews activities in RILEM which have stimulated the generation or dissemination of knowledge on durability of building materials. The paper emphasizes the need for international collaboration in durability research. Member of RILEM Technical Advisory Group International Union of Testing and Research Laboratories for Matérials and Structures. Based on a talk by James R. Wright, RILEM Seminar on Durability of Building Materials, Tokyo, Japan, October 13, 1984.     

Mass and heat transfer in building materials

A system of differential equations is proposed for mass and heat transfer in capillary-porous bodies. The principal thermophysical characteristics of mass and heat exchange in relation to building materials and structures are discussed.     

Sintered coal ash/flux materials for building materials

An Illinois coal ash, which has metals and a large amount of iron, is considered to be an especially difficult waster for disposal. In the process described in this paper, the high iron and metal content is used to create a building material with special properties. The metals are sequestered. The metals allow a process that creates valueadded products, building materials. The products are inexpensively prepared colored, strong, lightweight insulative structural panels. By either sintering in an oven at 725°C or by adding a flux and sintering at 525°C, panels are produced which will not leach metals from the ash. The use of an acid with the fly ash as a flux was investigated in comparison with fly ash control samples. The effects of sintering samples at different temperatures and with or without vacuum were also observed. Properties of the samples, including values for strength, water absorption, insulation, and color, are presented from this study.

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Résumé Une cendre de charbon de l'Illinois, qui a des métaux et une grande quantité de fer, est considérée comme un déchet particulièrement difficile à éliminer. Dans le processus décrit par cette étude, la teneur élevée en fer et en métal est utilisée pour créer un matériau de construction avec des propriétés spéciales. Les métaux sont isolés. Les métaux permettent un processus qui crée de la valeur ajoutée. Les produits sont des panneaux structuraux isolés, colorés, forts et légers qui sont préparés à peu de frais. On produit des panneaux qui ne lixivieront pas les métaux de la cendre par une concrétion dans un four à 725 degrés Celsius, ou bien par une concrétion à 525 degrés Celsius, en ajoutant un flux. L'utilisation d'un acide avec la cendre en l'air comme flux a été étudiée en comparaison avec des échantillons témoins de cendres flottantes dans l'air. On a également observé les effets de concrétionnement des échantillons à différentes températures avec ou sans vide. Les propriétés des échantillons, y compris les indices pour la solidité, l'absorption de l'eau, l'isolation, et la couleur, sont présentées dans cette étude.

     

Carbonation of ternary building cementing materials

The carbonation processes of ettringite and calcium aluminate hydrates phases developed by hydration of calcium aluminate cement, fly ash and calcium sulphate ternary mixtures have been studied. The hydrated samples were submitted to 4% of CO₂ in a carbonation chamber, and were analysed, previous carbonation and after 14 and 90 days of carbonation time, by infrared spectroscopy and X-ray diffraction; the developed morphology was performed with the 14 days carbonated samples. The results evidenced that ettringite reacts with CO₂ after 14 days of exposition time and evolves totally at 90 days; the developed hydrated phases C₃AH₆ in samples with major CAC content, also reacts with CO₂. Due to carbonation, calcium carbonate – mainly vaterite but also aragonite-, depending on the initial formulation, aluminium hydroxide and gypsum were detected.     

Carbonation of ternary building cementing materials

The carbonation processes of ettringite and calcium aluminate hydrates phases developed by hydration of calcium aluminate cement, fly ash and calcium sulphate ternary mixtures have been studied. The hydrated samples were submitted to 4% of CO₂ in a carbonation chamber, and were analysed, previous carbonation and after 14 and 90 days of carbonation time, by infrared spectroscopy and X-ray diffraction; the developed morphology was performed with the 14 days carbonated samples. The results evidenced that ettringite reacts with CO₂ after 14 days of exposition time and evolves totally at 90 days; the developed hydrated phases C₃AH₆ in samples with major CAC content, also reacts with CO₂. Due to carbonation, calcium carbonate – mainly vaterite but also aragonite-, depending on the initial formulation, aluminium hydroxide and gypsum were detected.     

相变储能材料在建筑中的应用

相变材料是一种高效的贮热物质,相变储能建筑材料是通过向传统建筑材料中加入相变材料制成,可降低建筑能耗,调整室内环境舒适度.本文对相变材料在建筑材料中的应用及存在的问题等进行了总结,并展望了发展前景.