Several types of cement were evaluated by using the waste indicator which reflected the recycling rates of recyclable resources for the purpose of developing an evaluation method to quantify the contribution of the waste use in cement to the environment. The evaluation based on the waste indicators reflecting the recycling rates of recyclable resources resulted in higher values in Portland cement (PC) than those in blended cements, suggesting a higher environmental contribution of the waste use in Portland cement compared to that in blended cements. Integrated assessment by the life-cycle impact assessment method based on endpoint modeling (LIME2) also showed that, the lower the replacement ratios of admixtures, the higher the environmental contribution of waste use would be. The values by these two different methods showed a high correlation with each other. These results suggest that the waste indicators reflecting the recycling rates of recyclable resources can be effective indicators for quantifying the contribution of waste use in cement to the environment.

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 Cement manufacturers are in the process of replacing conventional raw materials and fuels with by-products and wastes as a means to contribute to the environment. Alternative raw materials and secondary fuels contain minor elements which can influence burnability as well as properties of clinker minerals and cement. Burnability influences the amount of free lime in clinker, which results in variations in mineral composition and cement hydration. In order to optimize the use of alternative resources, this study evaluated the effects of minor elements on clinker minerals and cement hydration under a constant free lime effect and determined the limits of MgO, NiO, CuO, ZnO, TiO₂ and Ｐ₂O₅.
　Minor elements were classified into three groups based on similarity in the effect on clinker minerals. Group I including MgO and NiO was distinguished by the presence of periclase and periclase-like crystals. Group II including ZnO and CuO was characterized by negligible changes to the silicate phase along with, at high content, the formation of excess oxides which acted as a retarder in cement hydration. Group III including TiO₂ andＰ₂O₅ was defined by a decrease in C₃S. This study led to the following recommended limits for minor elements based on cement hydration and strength are as follows: MgO ≤ 2.00% for negligible effect, NiO ≤ 1.95% for negligible effect; CuO ≤ 0.48% for negligible effects; ZnO ≤ 0.97% for beneficial strength gain; TiO₂ ≤ 50% for negligible effects; and Ｐ₂O₅ ≤ 091% for negligible effects.

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 Pore-free concrete (PFC) was developed recently for the purpose of achieving the highest possible level of compressive strength in cast molded concrete. This study was performed to examine the applicability of fiber reinforced PFC to repair panels for coast retaining walls. Composite panels of ultra high strength fiber reinforced concrete (UFC) partially embedded with the fiber reinforced PFC were fabricated and successfully applied to the repair of severely eroded coast retaining walls in Hokkaido. It was also verified by measurements that the fiber reinforced PFC was stable in water in terms of compressive strength and had higher flexural strength and abrasion resistance compared to UFC.

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 This paper experimentally evaluates thermal cracking resistance of concrete containing 60% ground granulated blast-furnace slag and anhydrous gypsum to make total SO₃ amount in binders 3%, based on moderate-heat portland cement. Thermal stress behavior and cracking properties of the concrete were investigated by using the Temperature-Stress Testing Machine (TSTM) which was thermal stress simulation equipment of uniaxial restraint type. The results showed that the age of occurrence of cracking and tensile strain capacity of the concrete used in this study were obviously higher than those of concrete using portland blast-furnace slag cement type B. It was also suggested thermal cracking resistance of the concrete could be almost the same as that of concrete using moderate-heat portland cement singly.

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 Particle structure is one of the important characteristics for expanding the utility of calcium carbonate filler. This study focused on a hollow structure and investigated how to make calcium carbonate particles have such a structure. The spray drying and spray pyrolysis methods which have been conventionally used for manufacturing ultrafine particles were selected for that purpose, and single micrometer-sized hollow calcium carbonate particles were successfully obtained by adjusting the spraying conditions and heating temperatures properly. The obtained particles were calcite-type microspheres having a hollowness of more than 63vol% and an apparent density of below 1.0g/cm³. It was also possible to make surface pores either open or closed by optimizing the synthesis conditions such as solution compositions and heating temperatures. The proposed method is expected to expand the utility of calcium carbonate from a simply reasonable general-purpose filler into such useful materials as lightweight materials, thermal insulators, floating buoyant materials and microcapsule membranes.

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 The aim of this study is to establish a technique that enables quality control of blended cements based on the mineral composition. The XRD/PONKCS method with the advantage of no need for standard samples was selected and studied for its applicability to automated quality control system. In this study accuracy and usefulness of the technique were experimentally investigated in quantifying the mineral composition of cements containing amorphous admixtures. Good results were obtained with binary blended cements containing blast-furnace slag, fly ash or silica fume, with both amorphouss and mineral contents quantified with high accuracy simultaneously. Quantification of admixtures in ternary blended cement was also found possible, although its accuracy was lower than that with binary blended cement. The exception was the combination of fly ash and silica fume in ternary blended cement to which the XRD/PONKCS method was found inapplicable.
　Practical applicability of the XRD/PONKCS method to the inspection of slag ratio in Portland blast-furnace slag cement was examined using an existing automated quality control system at our cement plant. Adequately accurate quantification was obtained during the 6-month plant test, with only simple maintenance required. Consequently, it was demonstrated that the proposed technique could provide a means of quality control of blended cements based on the mineral composition.

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 There is an increasing demand for large scale tunnel construction in Japan, especially for the Chuo Shinkansen which will be the first Maglev train system in this country. Various materials and methods have been developed for tunnel construction to provide increased strength, reduced environmental impact and improved working conditions. High early strength shotcrete will be essential to the construction of the Chuo Shinkansen line which is planned to run through the soft ground conditions of the Southern Japan Alps. New shotcrete with significantly enhanced hardening property was developed to meet such needs. This report describes the investigation under real conditions in which construction performance and strength development were evaluated. The results demonstrated that the proposed technique using the new shotcrete had excellent construction performance in tunnel construction and was capable of achieving early strength development in the order of several minutes.

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