The environment surrounding the cement industry has greatly changed in these 30 years. In addition to the significant decrease in domestic demand for cement, we have been faced with such new challenges as CO₂ emissions and other environmental issues, many natural disasters occurring around the country and recoveries from them, and severe shortage of human resources. With a special focus on cementitious materials, this paper summarizes the technologies developed during this period and the future topics, including use of more wastes and by-products in the cement production, development of new cements, enhancement of functionality and durability of cement and concrete, investigation of new deterioration phenomena, and development of analysis techniques.

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 Increasing the amounts of minor additional constituents in ordinary Portland cement (OPC) is one of the effective approaches for reducing the CO₂ emissions from the cement industry. However, this approach should affect the performance of mortar and concrete. In this study we widely investigated the influence of increasing the minor additional constituents on the quality of cement. By varying the composition and fineness of the base cement as well as the type of minor additional constituents, the quality evaluation was carried out on the test cements containing minor additional constituents up to 10mass%. It was found possible to make the quality of the cement containing 10mass% minor additional constituents equivalent to that of current OPC by increasing the C₃S content by 0.7 to 1.5mass% and Blaine specific surface area by 100 to 200cm²/g.

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 Longer spans and higher durability of PC structures can be achieved by using ultra high strength concrete. Many types of ultra high strength concrete have been developed for that purpose and applied to real structures. In 2015, porosity free concrete (PFC) with a compressive strength of up to 400N/mm² was developed at Taiheiyo Cement Corporation. However, PFC exhibits a brittle failure behavior under tensile loading. Fiber reinforced PFC is a PFC matrix containing short fibers that can improve the brittle nature. Studies have been made to clarify the mechanical properties of the fiber reinforced PFC, but few has been studied about the structural properties of the fiber reinforced PFC. The purpose of this study was to investigate the shear behavior of thin and lightweight PC beams made of the fiber reinforced PFC. Bending tests using beams with high prestress levels showed that a fiber reinforced PFC beam prestressed to 40N/mm² had a significantly improved loading capacity compared to those with a prestress of 20N/mm² or no prestress. It was also found that shear capacity of fiber reinforced PFC beams was over the calculated estimation by the method proposed in the JSCE Recommendations for Design and Construction of Ultra High Strength Fiber Reinforced Concrete (UFC) Structures.

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 This study examined the effectiveness of self-curing effects of artificial lightweight aggregate on concrete that has been constructed under hot weather environment. First of all, we had the construction of the test specimens simulating the concrete slab and columnunder hot weather environment of more than 35℃. Types of concrete were normal concrete, the lightweight concrete type 1 and the concrete by replacing the part of the fine aggregate in the artificial lightweight fine aggregate. We evaluated the physical properties and the hydration reactivity of cement inside the hardened concrete. As a result, in comparison with normal concrete, the concrete using the artificial lightweight aggregate was improved in compressive strength and air permeability even in the atmospheric curing condition of the under hot weather environment. With respect to the lightweight concrete type 1, the effect on crack resistance was also observed. The analysis results of the hydration degree of the cement in hardened concrete also indicated that the hydration reaction in concrete using the artificial lightweight aggregate had progressed properly, confirming the effectiveness of the self-curing effect of lightweight aggregates.

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 Refrete system is a suite of repair methods developed for deteriorated concrete structures. RF method and DS method are commonly used nowadays. RF method is suitable for the repair of carbonated or frost-damaged concrete which uses a paint type surface penetrant containing a lithium silicate. On the other hand, DS method is a chloride attack damage repair which uses a paint type nitrite rust inhibitor in combination with a polymer cement mortar paste containing a rust inhibitor. Apart from the above two methods, a water proofing paint named REBORN is available for improving durability of concrete structures in the Refrete systems.
　In this report, experimental verification was performed on the Refrete DS method, and follow-up inspection was made on a practical example of RF REBORN method (a combined application of the DS method and REBORN).
　Experimental and follow-up inspection results showed that the DS and RF-REBORN methods would provide a satisfactory long-term durability.

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 A powder mixture of strontium aluminate and soda-lime glass was melted using the flame fusion method to obtain phosphorescent spherical particles coated with an inorganic glass phase. Some typical products were analyzed by X-ray diffraction (XRD) and X-ray fluorescence (XRF). To characterize the fluorescence property, excitation spectra and emission spectra were measured. In addition, optical microscopic observation and Scanning electron microscope with energy dispersive X-ray spectroscopy (SEM-EDS) analysis were carried out to examine morphological changes. Cross sectional observation and elemental mapping by the SEM-EDS method revealed that: (i)it was impossible to obtain phosphorescent spherical particles fully coated with a glass phase; and, (ii)strontium aluminate powder particles were solely sphericalized, with their afterglow luminance property unchanged.
　The results demonstrated that the SEM-EDS method would be one of the most useful analytical tools to obtain information about the cross sectional structure and high temperature reaction of inorganic fine particles.

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