To achieve high fluidity of fresh mortar and high compressive strength of hardened mortar in ternary blended cement systems for ultrahigh strength concrete, the influences of particle composition and curing temperature on mortar were examined. The ternary blended cement was produced by mixing moderate heat Portland cement as the coarse grain, silica fume as the fine grain and silica fine powder as the intermediate grain. Curing temperature was between 20℃ and 90℃. The flow value of fresh mortar and the compressive strength of hardened mortar were found to increase when the specific surface of silica fume was reduced from 20m²/g to 10m²/g. It was also found that high performance was achieved when a cement system consisting of 60vol.% of moderate heat Portland cement, 20vol.% of silica fine powder and 20vol.% of silica fume with a specific surface of 10m²/g was used, although the ratio of intermediate particles was higher than that calculated according to the theory of particle packing by Furnas. The other finding was that pozzolanic reaction was accelerated with the increase in the curing temperature, resulting in a reduced porosity. However, there was no obvious influence of the specific surface of silica fume on cement hydration and pozzolanic reaction.

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 The use of ultra high strength fiber reinforced concrete (UFC) has been increasing since the publication of recommendations on the design and construction of UFC structures by the Japan Society of Civil Engineers in September 2004. UFC is a unique cementitious composite with high tensile strength which enables concrete structure designs without reinforcing bars. Its durability is also very high compared to conventional concrete. UFC has been mainly applied to bridges, taking advantage of its high strength. The Sakata-Mirai Footbridge was the first bridge of UFC in Japan completed in October 2002. In this paper, the durability and the mechanical properties of the ten year old UFC bridge have been studied by using exposed specimens from the girder and core test pieces from the web. The major results obtained are shown below. (1) The compressive strength of the field specimens showed a gradual increase until the age of 10 years. (2) The flexural strength of the field specimens showed an almost linear increase until the age of 10 years. (3) The chloride ion diffusion coefficient obtained from the field specimens was much lower than that of laboratory immersed specimens. (4) The chloride ion diffusion coefficient in the test cores was lower than that of the field exposed specimens from the girder. (5) Examination of the exposed specimens and core test pieces by scanning electron microscopy revealed the presence of many unhydrated cement particles. (6) These findings suggest that UFC footbridges can retain good condition and mechanical properties for at least ten years even against severe environments, thus verifying the sustainability of UFC structures for the period of ten years.

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 Deposits composed of hard volcanic rocks such as andesite are widely found in the Hokuriku District. They provide good aggregates as river gravel or crushed stone. On the other hand, the regular supply of alkalis due to salt water splash from the Sea of Japan or the use of deicer mainly during winter may contribute to constant occurrence of alkali-silica reaction (ASR) in concrete using andesitic aggregates. With consideration given to the principle of local production for local consumption in construction materials ("Chisan-chisho" in Japanese) as well as reduction in both environmental impact and consumption of natural resources, the use of blended cements using fly ashes has been regarded as one of the most appropriate means of ASR suppression in the Hokuriku District. This paper examined the suppression effect of locally produced high-quality fly ashes with two typical examples of reactive andesitic aggregates used in the Hokuriku region. It was found that replacement with fly ash up to 20% which was appropriate for practical use could effectively suppress the ASR-induced expansion of the mortars. It was also found that polarizing microscope observation was valid for the evaluation of aggregate reactivity and the determination of the progress of reaction due to ASR.

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 The cement industry uses a wide variety of wastes as alternative raw materials and fuel. However, due to the high chlorine content of the wastes, their utilization could cause various serious problems. To solve such problems Taiheiyo Cement Corporation developed a chlorine bypass system, enabling use of the high chlorine content wastes. Having resolved the chlorine restriction to waste utilization, attention is now directed to the potential increase in heavy metals in the cement production process and, particularly, the possibility that the lead content of cement would exceed the limit stipulated in the in-house standard. Therefore, it was necessary to develop a new technique to address the increasing lead input associated with the increasing waste usage.
　Taiheiyo Cement Corporation developed a new efficient technique through many studies to recover lead from the cement manufacturing process that optimizes the functions of the Taiheiyo Cement chlorine bypass system and a wet purification process for lead. The new technique makes it possible to recover high-purity lead that itself can be used as the raw material for nonferrous metal smelting. This technique will help contribute to the formation of a recycling-oriented society by enhancing the waste utilization in the cement manufacturing process.

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 Lithium-ion batteries with high energy density are required for the applications to electric vehicles and hybrid electric vehicles. Cathode materials have attracted much attention to improve energy density in recent years. The Li₂Fe_0.5Mn_0.5SiO₄ family of compounds, where M is typically Fe, Mn, Co or Ni, is considered as one of the promising class of cathode materials for lithium-ion batteries of the next generation. In this study, crystallographic and morphological data, as well as galvanostatic cycling and rate performance, of the cation (Al³⁺, Zn²⁺, Mg²⁺) doped Li₂Fe_0.5Mn_0.5SiO₄/C (the Li₂Fe_0.5Mn_0.5SiO₄ family of compounds) were reported. The cation doped Li₂Fe_0.5Mn_0.5SiO₄/C consisting of uniform nano-sized primary particles with no impurities was successfully synthesized by hydrothermal method followed by carbon coating and was all indexed on the basis of the orthorhombic unit cell in space group Pmn2₁. The crystallite size of Li₂Fe_0.5Mn_0.5SiO₄/C was found to decrease with the cation doping. Although the capacity fading of the cation doped Li₂Fe_0.5Mn_0.5SiO₄/C was similar to that of the undoped one, the discharge capacity and the rate capability of Li₂Fe_0.5Mn_0.5SiO₄/C were improved by the cation doping. The Al doped Li₂Fe_0.5Mn_0.5SiO₄/C showed the best electrochemical properties with first discharge capacities of 216.9mAh/g at 0.01C and 159.6mAh/g at 0.5 C. These good electrochemical properties of it were attributed to the smaller crystallite size compared with the undoped Li₂Fe_0.5Mn_0.5SiO₄/C.

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 Effects of durability improvement curing agent "Curebrid" in curing the concrete and blocking the deteriorating elements were investigated in comparison with other commercial ones. Curebrid was found to have a satisfactory curing effect, with the specimens treated with Curebrid exhibiting a reduced weight change under indoor conditions and an enhanced compressive strength in the outside environment as compared to those without Curebrid application. Moreover, the results of accelerated carbonation test and chloride ion permeation test showed that Curebrid improved durability of concrete against carbonation and salt attack. In particular, the effect of inhibiting carbonation was significantly high. The effect on long-term durability was also verified in the exposure test, heating-cooling cycle test and weather-resistant test because water penetration into the specimens was successfully prevented after tests.

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 Taiheiyo Cement Corporation has been working on research on processing of waste with high chlorine contents. One of the achievements is a development of a system to capture organic chlorine contained in waste plastics as inorganic chlorine by means of external heating and superheated steam and wash the heat-treated waste plastics with water, producing dechlorinated fuel which can be used for cement calcination. The heat treatment process in this system was tested at a pilot-scale demonstration plant. The test results showed dechlorination was successfully accomplished, with 42% of the total chlorine in the raw material converted to inorganic compounds and 38% to volatile chlorine, while retaining the heat within the treated product. When alkali was added to the raw material in another trial, 90% or more of the total chlorine in the raw material was successfully converted to inorganic compounds, without producing volatile chlorine.

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