A new mix design of ordinary Portland cement (OPC) with increased minor additional constituents and aluminate phase has been investigated to achieve both reduction in CO₂ emissions and increase in recycled material use. In this study, the relationship between heat of hydration of cement and thermal property of concrete was studied, and the validity of the conventional method of measuring the heat of hydration of OPC was investigated. Concrete using a cement containing 10% of minor additional constituents with aluminate phase increased by approximately 1% exhibited almost the same adiabatic temperature rise as that using the conventional OPC. Heat of hydration at 28 days determined in accordance with JIS R 5203：2015 showed an increase of heat by 20 J/g. The value was found to be only 10 J/g when determined by a modified method which did not consider the amount of loss on ignition (LOI). This suggests that the modified JIS method is likely to be more accurate in estimating the index of thermal property of concrete, as it can correct overestimation in heat of hydration by JIS R 5203：2015, especially for high LOI cements.

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 In this study, artificial fine aggregate containing large amounts of waste materials was designed in an effort to contribute to building a recycling-oriented society, and the performance of the mortar and concrete using it was evaluated. A rotary kiln commonly used for mass production of artificial aggregate was assumed for the manufacturing process of the new aggregate. The desirable chemical composition of raw materials, which was the most important factor for stable and continuous kiln operation, was determined through the laboratory firing experiments. The artificial fine aggregate with the most suitable raw mix thus obtained was fired using a pilot-scale rotary kiln, and the fired product was crushed and sieved. To evaluate the artificial fine aggregate, physical properties of the mortar and concrete using it were investigated. The test results showed that a raw mix chemical composition with hydraulic modulus (HM) = 1.10 and silica modulus (SM) ≦ 2.40 would be the most suitable for the stable rotary kiln operation. The new aggregate was found to have an extremely low hydraulic property in spite of the presence of belite and be able to survive long-term storage due to the absence of free CaO harmful to concrete. Compressive strength and durability of mortar and concrete using the new fine aggregate were almost the same as those with conventional fine aggregate products.

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 The purpose of this study was to investigate the performance of steel fiber reinforced porosity free concrete (PFC^Ⓡ), a newly developed ultra-high-strength concrete with a compressive strength of about 400 N/mm², in protection against fast collision. Missile collision tests were conducted on the PFC panels, taking the mixing ratio of steel fibers and the impact speed as variables. The same tests were also conducted using ordinary reinforced concrete (RC) panels with a compressive strength of about 30 N/mm² to investigate the effects of compressive strength on the impact resistance behavior of concrete panels. The following findings were obtained from this experimental study: 1) impact resistance capacity of the steel fiber reinforced PFC panels was significantly higher than that of the RC panels; and, 2) the application of the steel fiber reinforced PFC to protection panels provides reduction in size, weight and constriction cost.

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 The effects of cathode compositions including 90–99 wt.% active material on the electrochemical performance of lithium-ion batteries were studied. The cathodes were comprised of LiMn_0.7Fe_0.3PO₄/C secondary particles as the active material, acetylene black (AB) as the conductive additive, and polyvinylidene fluoride (PVDF) as the binder in Nmethyl-2-pyrrolidone. The area ratio of the active material on the cathode surface analyzed by backscattered electron imaging was found to decrease with the increase in the AB content in the cathodes. The electrical conductivity of the cathodes increased with the increase in the weight ratio of AB and the decrease in the weight ratio of the active material in the cathodes. The discharge capacity of the cathodes including 90–99 wt.% active material was between 153.1–157.3 mAh g⁻¹ at a current rate of 0.2 C, showing an increase with the decrease in the weight ratio of the active material. Their energy density was found to be between 560.5–592.0 Wh kg⁻¹. In addition, the capacity retention rate of the cathodes having 90–98 wt.% active material was between 79.8–91.5% at current rates of 5/0.2 C, showing an increase with the decrease in the weight ratio of the active material in the cathodes. This was likely due to the low R_ct associated with the decreasing weight ratio of the active material. Among the cathode compositions with an AB/PVDF weight ratio of 1/3, 1 and 3, those with AB/PVDF=1 were found to achieve the lowest R_ct and thus the best rate capability with any active material ratios.

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 This paper presents the results of evaluation of fresh properties, allowable time for successive placements, strength properties, and pore size distribution of ultra-high-strength concrete containing silica fume-premix cement (SFPC^®) at mixing temperatures of 33℃, 38 and 45℃. It was found that the target slump flow could be satisfied at all mixing temperatures with the standard admixture rate, that the allowable time for successive placements could be met by changing the type of admixture to be used and adjusting the addition rate, and that the compressive strength was almost the same among the mixing temperature of 33℃, 38 and 45℃ regardless of water curing and simple adiabatic curing. It was also revealed that there was no significant difference between the mixing temperatures of 33℃, 38 and 45℃ in the structural strength correction value of ₂₈S₉₁ calculated from the strength obtained by simple adiabatic curing.

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