Cement is a material used for bonding other materials together, and as a binder in concrete. The term cement is most commonly used to refer more specifically to powdered materials, which develop strong adhesive qualities when combined with water. These materials are more properly known as hydraulic cements. Portland cement is by far the most common and most important hydraulic cement in modern construction. Gypsum plaster and common lime are not hydraulic cements. Using ground granulated blastfurnace slag (GGBS) with three different levels of basicity ranging from 1.63 to 1.90, this study evaluated cement strength development at 10, 20, and 30°C and analyzed the hydration products. The hydration analysis was made by XRD/Rietveld, chemical composition of C-S-H was determined by SEM-EDS, and pore size distribution was measured by MIP. The strength development of cement with lower basicity GGBS was found to improve at higher temperatures and longer ages of curing, showing its higher temperature-dependency compared to that with higher basicity GGBS. The cement paste with lower basicity GGBS was found to have a higher proportion of C-S-H in its hydrates, which suggested a significant contribution of C-S-H formation to the strength enhancement in lower basicity GGBS cement.

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Excessive expansion (overexpansion) may occur in a relatively short period of time when hardened paste of rapid hardening cement is subjected to water absorption after heating. In this study, hardened specimens of rapid hardening cement were prepared in different sizes, heated under different temperatures between 65°C and 120°C, and then immersed in water to investigate their expansion behavior, as well as cracks in appearance and changes in the strength of the hardened cement. It was found that overexpansion was likely to occur when the heating temperature was above 100°C, and that the effect of overexpansion was more significant in the smaller specimens. In the specimens with larger sizes and restrained by steel reinforcement, even when heated at above 100°C, the effect of overexpansion was found to be limited to the vicinity of the surface of the hardened cement, with no significant impairment to the mechanical properties as a structural member.

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 A low-carbon cement was developed in this study as part of development of CCU technologies using cementitious materials. The cement is made low in carbon by adjusting its chemical composition and characterized by its ability to harden during carbonation curing. As an application of the low-carbon cement to precast concrete products, two types of carbonation-cured low-carbon interlocking (IL) blocks were manufactured by carbonation curing in CO₂ gas, and their properties were evaluated. It was found that the IL blocks of ordinary type and of water permeable type satisfied the JIS A 5371 requirements specified for roadway IL blocks and for permeable sidewalk IL blocks, respectively. Evaluation was also made by means of LCA on avoided CO₂ emissions to be achieved by substituting the carbonation-cured low-carbon IL blocks for conventional IL blocks. The results showed that the avoided CO₂ emissions by the use of the carbonationcured low-carbon IL blocks would be 69.1 kg/t. These results of evaluation on the properties and avoided CO₂ emissions indicated the effectiveness of the carbonation-cured low-carbon IL blocks developed in this study as a CCU technology.

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 A slump test is a standard method to evaluate fluidity of fresh concrete as one of the quality control items in concrete production. With an increasing demand for improved productivity in the field of concrete, research has been conducted to establish a technology to predict the slump of concrete from video information of concrete mixing by using AI. However, no sufficient quantitative evaluation has been made on its prediction accuracy and variation. In this study, AI slump prediction was performed by using image data of concrete mixing inside a mixer for training, and the predicted values were analyzed to determine the accuracy rate and statistically evaluate the variation. The results showed that the AI-predicted slump values had a high accuracy rate within the tolerance specified by the JIS, with a smaller variation compared to that in slump test results. After verification at our factory, the AI slump prediction system has been completed as a product of joint development with Pacific System Co., Ltd. and launched under the name of PreSLump AI^Ⓡ in April 2023.

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 A sewage sludge drying system (TTR^Ⓡ-D), which uses hot meal extracted from a cyclone preheater as a heating source, and a waste plastics gasification system (TTR^Ⓡ-G), which also utilizes hot meal, have been commercialized by Taiheiyo Engineering Corporation. This paper describes the two systems, including the technologies and the results we developed. The TTR^Ⓡ technology can be applied to heating and separation technologies, and a brief introduction is also given about such future applications.

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