Feature analysis of fly ash was carried out for five different fly ashes (equivalent to JIS Class II) with varied levels of alkali-silica reaction (ASR) suppression effect. The purpose of this study was to identify the chemical and physical characteristics of the fly ashes in relation to their ASR suppression effect. The equipment used was a scanning electron microscope (SEM) combined with backscattered electron (BSE) detector, energy dispersive X-ray spectrometer (EDS) and electron backscattered diffraction (EBSD) system. The authors classified fly ash particles into five phases quantitatively by the feature analysis and determined the volume fraction, particle size distribution and specific surface area of each phase. Several amorphous phases were found in the fly ash particles, and an index calculated from the specific surface area and silica content indicated a negative correlation between the phase with Al₂O₃-SiO₂ and the 14-day expansion of mortar bar determined in accordance with ASTM C 1260. The results suggested that this amorphous phase would be a major determinant factor of the ASR suppression effect of fly ashes.

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 A method of estimating the chemical composition of cement in hardened concrete using an electron probe microanalyzer was studied for identifying the cement types used in the concrete. Concrete specimens were prepared using ordinary Portland cement, and mapping analysis was performed on a square area of 400 micrometers by 400 micrometers on each specimen to quantify the nine major elements of cement. The size of a pixel was fixed to 1 micrometer by 1 micrometer in the analysis. The quantified values of the elements (as oxides) in each pixel were converted to make the sum 97% with the relative proportions kept unchanged to obtain a converted composition. Pixels corresponding to aggregate were excluded based on the values of CaO, and an average of the converted compositions was calculated for the remaining pixels representing cement and hydrates to obtain an estimated composition of the cement. The estimated composition was found close to that determined by fluorescent X-ray analysis. This method was applied to the concrete samples collected from existing structures and demonstrated to be capable of identifying the cement types used in them correctly.

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 The ultra high strength fiber reinforced concrete (UFC) recently developed has high strength, high flowability and high ductility. The use of UFC has made it possible to obtain lightweight and highly durable structural concrete members. However, autogenous shrinkage tends to be larger in UFC due to the lower water-binder ratios and higher curing temperatures as compared to ordinary concrete. The authors prepared reinforced concrete (RC) beam specimens using UFC with shrinkage reducing agents and carried out loading tests on them to verify the effects of shear carrying capacity improvement. The results demonstrated that shrinkage of UFC decreased with the addition of shrinkage reducing agents, increasing the fracture energy and, thereby, improving the shear properties of the RC beams.

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 TAIHEIYO CEMENT CORPORATION installed a potassium salt recycling system at their Kumagaya Plant in Japan for recovering commercial quality salt from chlorine bypass dust.
　However, variable operating costs including those of electricity, fuel oil and chemicals turned out to be so high that the economic viability of the recycling system was brought into question. Modification efforts were made to reduce the operating costs through development and introduction of new techniques. Desired cost reduction was achieved after many trials by eliminating the need for chemicals to remove Ca ions from the bypass dust washing filtrate.
　The newly introduced techniques include the followings: a dissolution tank with a feature of reducing Ca ions dissolved in the chlorine bypass dust slurry; nonchemical removal of dissolved Ca ions from the brine; and a combination of dryer and granulator to replace the conventional electro-dialyzer and evaporative crystallizer for the reduced consumption of electricity and fuel.
　With successful introduction of these new techniques, the operating costs were reduced to only 35% of those before the modification, while the recovered potassium salt exhibited a high quality that completely satisfied the Japanese standards for the use as a fertilizer raw material.
　This paper is a report of detailed features of the new potassium salt recycling system with low operating costs.

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 Immobilization treatment is one of the heavy metal containment technologies specified in the Soil Contamination Countermeasures Act of Japan. There are many recent reports about a magnesia-based material used to treat heavy metal-contaminated soils. However, the pH of the soil treated with the magnesia-based immobilizer is about 10, falling out of the neutral range (pH 5.8 to 8.6) specified by the effluent standards of Japan. The authors developed a new heavy metal immobilizer with soil neutralizing effect DENITE MP^Ⓡ and examined its performance. It was demonstrated in this experiment that the heavy metal immobilization capacity of the new product was equivalent to that of the conventional one, and that the final soil after the treatment had neutral pH levels. The immobilization effect of DENITE MP^Ⓡ was found high with lead, arsenic, selenium, chromium hexavalent and fluorine within the limits of this experiment.
　This study also confirmed that heavy metals in the soil treated with DENITE MP^Ⓡ were stable under acidic or alkaline condition. In addition, the cone index was improved to above 200kN/m² by the treatment with DENITE MP^Ⓡ, irrespective of the soil type.

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 Expanded perlite or obsidian are manufactured by heating perlite or obsidian for expansion, with the particle size controlled. The quality of expanded perlite or obsidian is known to be affected by inadequate heating which can produce unexpanded or incompletely expanded particles. In this study the authors determined the optimum calcination method and established quality improvement technology for each of them whose production methods are different from each other. In addition, use of a fluidized bed furnace was examined for their production and found promising with a possibility of producing high quality product with less unexpanded particles.
　It was also revealed that the differences between perlite and obsidian in their expansion mechanisms and final product qualities were attributable to the differences in their water contents and morphological features of glass.

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