Packing state of cement considerably affects the fluidity of cement paste and mortar. In this study, designing of the optimum cement for high strength concrete is conducted, adjusting the particle size distribution of cement to raise the packing ratio and to enable the concrete mixing at a lower water-cement ratio. Highly packed cement produced by adjusting the fineness of clinkers exhibited higher fluidity, and the fluidity was found to have good correlation with the packing ratio of the cement. The cement produced by mixing silica fume to low-heat Portland cement was found most packed when the silica fume content was 17.5mass%. This kind of cement also exhibited higher fluidity at higher packing rates, and the most packed cement achieved the maximum compressive strength under the same fluidity conditions. The compressive strength was over 170N/mm² in the clinker-adjusted cement and over 210N/mm² in the silica fume-added cement at 91 days of water curing at 20℃.

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 The freeze drying process for hardened cement consists of a freezing step by liquid nitrogen and a drying step by vacuum. Since the use of liquid nitrogen involved the risk of cracking due to heat impact, the authors made improvement to existing freeze-drying equipment to minimize heat impact on specimens and tested various freezing conditions and drying temperatures in the current study. The specimens used in this experiment were hardened bodies of hauyne-containing cement with ettringite which was susceptible to structural destruction by drying. The authors determined from a comparative study the optimum drying conditions non-altering to ettringite where peak area measured by the powder X-ray diffraction remained almost unreduced. The pore size distribution of the specimens prepared by the proposed method was found to differ significantly in major pore diameter and total pore volume from those of the specimens dried by commonly used D-drying or drying at 105℃. The pore size distribution results were also interpreted to represent the extremely fresh condition in which most of ettringite remained intact.

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 analysis (FIA). The pyrolytic method is rapid and simple as compared to the standard distillation method (CAJS I-51) specified by the Japan Cement Association. However, the pyrolytic method presented consistently higher values than those obtained by the distillation method. The purpose of this study was to identify the cause of the difference between the results of pyrolytic method (pyrolysis F values) and those of distillation method (distillation F values), and validate the proposed method. A comparative experiment was carried out for the validation, applying the pyrolytic method to various cement raw materials including lime stone, silica rock, blast-furnace slag and gypsum, and evaluating the pyrolysis F values against the distillation F values. The pyrolytic and distillation methods presented similar F values for specimens not containing SiO₂. However, the pyrolytic method presented higher F values than those obtained by the distillation method for specimens containing SiO₂. The cause of this difference was found to be the silica gel (amorphous SiO₂) formed during the distillation process which was considered to decrease the volatilization rate of fluorosilicic compounds. The degree of the effect was dependent on the SiO₂ content and the specific surface area of silica gel. Furthermore, the distillation F values approached the pyrolysis F values when the distillation time was increased. The proposed method was found to be highly reliable. It was also rapid and simple, requiring only 15 minutes for pretreatment. Consequently, the proposed method is highly practical for routine quality control operation.

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 New types of artificial lightweight aggregates with high strength are recently available. Most of them are pelletized and coated lightweight aggregates made from finely ground minerals. Their water absorption is low due to their completely coated surfaces and the interior consisting of closed micro-cells. With application of these high-performance lightweight aggregates, structural concrete with high workability, high strength and high durability can be produced.
　When this kind of concrete is used in reinforced concrete (RC) members, however, the shear carrying capacity decreases due to the increase in autogenous shrinkage and the decrease in fracture toughness. To clarify and to take advantage of combined effects of synthetic short fiber and shrinkage-reducing agent on improvement of shear carrying capacity, loading tests were performed using high-strength lightweight RC beams.
　Since the conventional equation for evaluating shear carrying capacity recommended in JSCE Standard Specifications for Concrete Structures cannot be applied to structures using high-strength lightweight concrete, some practical method needs to be developed for the application of such concrete to structural members. The authors performed shear loading tests on RC beams to investigate their shear resisting mechanism and proposed a new evaluation equation for shear carrying capacity of high-strength lightweight RC beams with the effects of synthetic short fiber and shrinkage-reducing agent taken into account. The proposed equation was demonstrated to provide a good agreement with the experimental results.

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 To promote the application of interlocking blocks to road pavement, the authors examined performance of existing interlocking block pavements at 50 locations on roadways which have been in service for ten years or more in Japan. The pavements were found in good serviceable condition at approximately 94% sites, and repair was needed at only about ４% sites. With repair conditions determined based on these results, 40-year life-cycle costs of interlocking block paving were estimated for normal roadway Class N₃. The examination results revealed that the interlocking block paving had lower life-cycle costs as compared to asphalt paving.

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 To prevent spontaneous combustion of sub-bituminous coal, the effects of surface reforming and various aqueous solution sprays on the oxygen absorption of coal were evaluated by BOD OxiTop method.
　The surface reforming experiment results revealed that CO₂ exposure or spray of aqueous solutions (Ca(HCO₃) ₂, Ca(CH₃COO) ₂, KCl) after HCl washing inhibited the low-temperature oxidation by the effect of ion exchange.
　Meanwhile, the results of aqueous solution spray experiments suggested that wood vinegar, anti-deicing fluid, waste car coolant and glycerin aqueous solution had good coating effect when sprayed to control the atmospheric oxygen diffusion.

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 Presence of late-expansive aggregate in concrete has been recently recognized as one of the critical problems associated with alkali-silica reaction (ASR). It has been pointed out that accurate evaluation of ASR potential of late-expansive aggregate is impossible with the present Japanese Industrial Standards (JIS) test method. The problem of late-expansive aggregate has been known for long in overseas countries, and some practical methods have already been proposed. Meanwhile, few research has been made on such aggregate to date in Japan. This paper reports an examination made on cores taken from an existing concrete structure containing sea sand as fine aggregate.
　The applicability of petrography method to the detection of late-expansive aggregate and the evaluation method for diagnosis from three different accelerated expansion tests were investigated. The results revealed that the structure has less potential for further expansion and that the Canadian method was the most appropriate for diagnosis in case of containing late-expansive aggregate.

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