材料
Online ISSN : 1880-7488
Print ISSN : 0514-5163
65 巻 , 11 号
選択された号の論文の15件中1~15を表示しています
特集 コンクリート用骨材および混和材料
総説
  • 浅見 誠
    2016 年 65 巻 11 号 p. 761-766
    発行日: 2016/11/15
    公開日: 2016/11/20
    ジャーナル フリー

    Copper slag is a byproduct of the copper smelting process at copper smelters and refineries. There are five copper smelters in japan. Let me introduce the efforts of the Mitsubishi Materials Corporation for one of examples. Mitsubishi Materials Corporation has two smelters located in Naoshima (Naoshima-cho, Kagawa prefecture) and Onahama (Iwaki-shi, Fukushima prefecture) respectively that produce copper slag. The copper concentrate―the primary raw material used in copper smelting―is imported almost entirely from Pacific Rim countries such as Chile and Canada after their domestic mine, Akenobe, was closed in 1987. Besides the copper concentrate, They actively take and treat recycled raw materials such as shredder dust which is made from the destruction of electronic scrap substrates from household appliances, personal computers, smartphones and used cars, after the collection of recyclable iron and similar metals. They use these raw materials for thermal energy and focus on collecting and recycling the valuable metal from these so-called "urban mines" (electronic gadgets from which metal can be taken). As a result, Naoshima and Onahama smelters and refineries, their process has become one of the most large capability recycled raw material management systems in the world. As the copper smelters and the cement factory both use the raw materials which are produced as a byproduct each other, it creates a recycling loop that doesn’t need a final disposal site. The effective use of copper slag, which is a byproduct of copper smelting, is related to environmental preservation and the restrained consumption of natural resources, in particular, it is very important not only in the development of a recycling-minded society, but it also affects the maintenance and development of the copper smelting business. Although copper slag is effectively used as an iron raw material for cement as mentioned above, we continue to drive for further spread for domestic market as a concrete fine aggregate and so on. In introducing copper slag here we hope this report will heighten awareness of copper slag and lead to an increase and spread in its uses

解説
論文
  • 鶴田 浩章, 竹本 裕樹, 上田 尚史
    2016 年 65 巻 11 号 p. 773-778
    発行日: 2016/11/15
    公開日: 2016/11/20
    ジャーナル フリー

    In recent years it tends to increase in the percentage of sewered population and increase in the generation rate of the sewage sludge every year. And weight reduction and effective utilization of sewage sludge and sewage sludge incinerated ash are desired more. In this research, authors aimed to use sewage sludge incinerated ash as admixture for concrete and make the influence to concrete clear. Sewage sludge incinerated ash has high ratio of restraining water, bad dispersibility by powder properties and the phosphorus included in the incinerated ash, make the setting of cement delayed. Therefore improvement of setting properties was measured by giving the condition to suggest reduction of setting time, and it was examined what kind of influence came to properties of setting and strength in mortar or concrete. To improve setting properties, authors used sewage sludge incinerated ash that was controlled the grading, limestone fine powder and accelerator, and to investigate the reason of delay on setting, the initial hydration temperature was measured. As a result, it was found that the use of limestone fine powder or accelerator enabled to reduce the setting time. This is because the promotion of initial hydration of alite by limestone fine powder or accelerator can reduce the setting time. So, authors found out that setting properties were influenced by C-S-H which makes promote initial hydration of alite. It's possible to use many sewage sludge incinerated ash as concrete materials by using these improvement methods, and we can think the utility value as the concrete material may generate.

  • 野村 博史, 野口 貴文, 武藤 貴彦, 奥野 翔矢
    2016 年 65 巻 11 号 p. 779-786
    発行日: 2016/11/15
    公開日: 2016/11/20
    ジャーナル フリー

    The relationship between compressive strength and cement hydration reaction was investigated to clarify the strength evolution mechanism of ultra-high-strength concrete with silica fume and fly ash. Compressive strength of concrete and pore volume of cement paste were measured. In addition, an index of C-S-H volume was estimated based on XRD/Rietveld analysis, thermogravimetric analysis and pozzolanic reaction analysis. As a result, it was recognized that a higher compressive strength was associated with a lower pore volume. Moreover, a lower pore volume was associated with a higher C-S-H volume. Therefore, it can be said that gel pore and capillary pore of cement paste were filled up with C-S-H when concrete with a low water-to-binder ratio received a heat treatment of 70 to 90°C and that a compressive strength of 200 N/mm2-class was caused by the solidity of micro structure in cement paste. With regard to the material characteristics, it was revealed that pozzolanic reactivity of admixture and mineral composition of Portland cement affected compressive strength of ultra-high-strength concrete. In contrast, Blaine specific surface area of Portland cement had little effect on it.

  • 伊藤 慎也, 盛岡 実, 伊代田 岳史, 丸山 一平
    2016 年 65 巻 11 号 p. 787-792
    発行日: 2016/11/15
    公開日: 2016/11/20
    ジャーナル フリー

    Hydration mechanism of calcium aluminate aggregate was examined. In order to confirm the hydration property of calcium aluminate aggregate, hydrate in the paste specimen which was mixed grinded calcium aluminate aggregate, Ca(OH)2 and water was confirmed by XRD. And also hydrate in the paste which was added CaCl2 to above paste was confirmed. The hydrates in the mortar with calcium aluminate aggregate were confirmed by XRD and TG-DTA, and these hydrates were observed by SEM image. In addition, the hydrates were confirmed by EDS and same examinations were carried out for the mortar with natural sand for comparison. Author confirmed that grinded calcium aluminate powder reacts with Ca(OH)2 which is provided as a cement hydrate and it generates hydrocalumite. Furthermore, there was a property to change to Friedel’s salt when a chloride ion acted. When the calcium aluminate is used for mortar as fine aggregate, a hydration was occurred at the aggregate surface and it was confirmed to generate hydrocalumite and hydrogarnet in the aggregate surface section. As a result, the possibility that a transition zone of mortar was modified by using the calcium aluminate aggregate was suggested. In the mortar which after salt water immersion, chloride ion penetration depth of mortar with calcium aluminate aggregate was smaller than ordinary mortar. And the hydrate formed layer was confirmed at the fine aggregate surface and its Ca/Al or Cl/Al molar ratio was similar to Friedel’s salt. And hydrates which Ca/Al molar ratio is 1.5 to 2.0 were also confirmed on the surface of calcium aluminate aggregate.

  • 羽村 陽平, 高谷 哲, 上田 尚史, 廣井 幸夫, 山本 貴士
    2016 年 65 巻 11 号 p. 793-799
    発行日: 2016/11/15
    公開日: 2016/11/20
    ジャーナル フリー

    Alkali-silica reaction (ASR) can be said one of serious problem concerning with concrete structures, because ASR causes not only cracks by expansion of reaction products with water absorption but fracture of reinforcing steels. At this point, for ASR suppression, use of non-reactive aggregate, use of low alkali cement or blended cement, or limit of alkali content is recommended, and it is well known that these countermeasures have ASR controlling effect to some extent. However, especially for important structures or structures expected to have long term service life, ASR should be prevented perfectly. And for it, accurate and rapid judgement method of ASR reactivity is required. Then in this study, Raman spectroscopy was focused as quick and easy analytical method, and in order to evaluate ASR reactivity or ASR propagation level by this method in the future, property of Raman spectrum of ASR reactive aggregate and reaction products were investigated as a basic study.

総説
  • 小林 隆夫
    2016 年 65 巻 11 号 p. 801-811
    発行日: 2016/11/15
    公開日: 2016/11/20
    ジャーナル フリー

    Fracture surface topography analysis (FRASTA) technique reconstructs fracture process in microscopic details by matching conjugate fracture surface topographs. It produces three different results: fractured area projection plot (FAPP), cross-sectional plot (XSP), and fracture progression curve (FPC). FAPP shows graphically where the crack initiation site(s) is and how it grew. By superimposing a series of FAPPs over a scanning electron microscope image of fracture surface, we can establish relationships between fracture process and microstructures. XSP is used to characterize the crack tip opening displacement or crack opening angle. Use of these two results is seen in published papers where the crack initiation mechanisms could not be determined by regular fractographic examination. However, these two results do not indicate the kinematics of crack growth. FPC shows the relationship between fractured area and the spacing between conjugate surface topographs. This relatively unexplored relationship shows the crack growth history from the onset of microcrack initiation to the rupture of the component, and by analyzing this relationship such information as crack initiation time, crack growth rate, changes in loading conditions or environment can be learned. This paper presents some examples of use of FPC in failure analysis.

論文
  • 飯塚 智則, 大武 義人, 田中 敬二
    2016 年 65 巻 11 号 p. 812-817
    発行日: 2016/11/15
    公開日: 2016/11/20
    ジャーナル フリー

    Photo-degradation of polymers for outdoor use are accelerated by degradation factors such as heat and moisture. Polypropylene(PP)is excellent in water resistance, but is inferior to weatherability. Therefore, in this study, PP was exposed under the water spray condition by using Xenon arc lamp. We evaluated the synergistic effect of light and moisture using the quantification technique of degradation. Results from the Fourier-transform infrared spectroscopic and X-ray Photoelectron Spectroscopy revealed that moisture accelerated the oxidative degradation of PP. In addition, with the progress of the oxidative degradation, melting point and thermal decomposition temperature of PP was lowered. The resulting collapse of crystal structure and chain scission therefore deteriorated the mechanical properties (Charpy impact strength, elongation ) of PP.

  • 岡崎 慎一郎, 片岡 洋輝, 松島 学
    2016 年 65 巻 11 号 p. 818-823
    発行日: 2016/11/15
    公開日: 2016/11/20
    ジャーナル フリー

    Resent research has focused on the potential loss in structural performance of reinforced concrete members with ASR related damage. In this research, deterioration and remained pulling shear stress evaluation method for ASR damaged concrete foundation of steel tower is developed by aiding finite element method. Expansion strain occurred on site due to ASR was identified by sensitive analysis of ASR model with comparing measurements of cracking pattern, crack width distribution and crack density of crown and body of concrete foundation. This method can evaluate stress state of concrete, rebar in structure and decreasing tendency of pulling shear stress corresponded to concrete expansion by ASR.

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