This study examined strength development and setting time of fly ash cements which were prepared using different base cements with varied mineral compositions, limestone powder contents and fineness levels. Hydration behaviors of these fly ash cements were also analyzed. It was found that alite hydration was accelerated in cements with higher alite contents, higher f-CaO contents and higher fineness, resulting in an increased short term strength. Long term strength was significantly increased by adding limestone powder which accelerated the hydration of fly ash. As a result, the fly ash cements containing the base cements with higher fineness and proper additions of alite, f-CaO and limestone powder exhibited strength and setting time comparable to that of ordinary Portland cement. The fly ash cement containing the base cement with 5% limestone powder was tested over 91 days (at 5, 20 ºC and 30 ºC) and was found to achieve a strength of 92% that of OPC, with the setting time being in a range between those of conventional fly ash cement and OPC. It was also found that the optimized fly ash cement had a lower heat of hydration and higher fluidity as compared to OPC.

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 A large amount of waste is used in the current cement industry as an alternative raw material for cement clinker. However, it is expected that use of waste will decrease with a decrease in cement production in the near future, indicating a need to find new destinations of use for clinker. One of new possible uses of clinker is as alternative aggregate for concrete. Clinker as aggregate in concrete has possibility to improve strength and durability of the concrete by its own reaction. This research investigated the physical properties of mortar using ordinary portland cement clinker and belite-gehlenite clinker as fine aggregate. We also analyzed the interfacial transition zone to investigate the mechanism of the improvement of strength and durability. The results showed that the clinker aggregate was capable of densifying the interfacial transition zone and, accordingly, improving the strength and carbonation resistance of the concrete.

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 There have been many studies on strength development and durability of concrete containing ground granulated blast-furnace slag (BS). Recently, concrete with a high content of BS is studied as a means of carbon-dioxide reduction. However, few studies have been carried out on the shear capacity of reinforced concrete (RC) beams with a high BS content. The purpose of this study was to investigate the shear resisting mechanism of RC beams with a high BS content by shear loading tests. The important findings in this study were as follows: (1) both compressive strength and elastic modulus of concrete containing BS were smaller than those of normal concrete at the age of 28 days; (2) BS concrete exhibited increased shrinkage as compared with normal concrete until the age of 28 days; and (3) shear capacity of the RC beams containing BS was 11% lower than that of normal RC beams with equivalent compressive strength.

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 Seismic retrofitting of buildings in Japan will be accelerated with the 2013 amendment to the Act on Promotion of Seismic Retrofitting of Buildings. The amended Act covers all small buildings and houses including apartments where placement of fresh concrete can be difficult. For use under such conditions, a premixed-type non-shrink grout concrete containing pea gravel was developed. This study evaluated fluidity, hardening properties and durability of the product. We also investigated the effectiveness at site and confirmed that the product could be placed at any time convenient for the site by compact operation using a small scale equipment. The results suggested the capability of the product as an alternative concrete for the use in small-scale casting.

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 Shrimp is one of the most worldwide popular aquaculture species. Shrimp culture is widely spread especially in the Southeast Asian region due to its higher feed conversion efficiency compared to livestock farming or other fishery products. However, deterioration of productivity has become a serious problem due to poor water quality of aquaculture ponds and diseases of shrimp.
　Use of Ceraclean, a porous calcium silicate hydrate product, is becoming common mainly in Southeast Asia for the maintenance of shrimp pond water quality and improvement of productivity. Ceraclean is a water purification material that enhances the activity of useful bacteria, promotes decomposition of sludge at the bottom of ponds and maintains the water environment properly. It is shown in this study that Ceraclean helps diatom become and remain dominant in the aquaculture water by constantly and continuously supplying silicate to the water, while absorbing nitrogen oxides that deteriorate water quality. The study results also show various good effects that diatom has. Diatom is a good feed for shrimp by itself, which contributes to the improvement of feed efficiency. Being dominant in the pond water, it can also help improve the survival rate by suppressing growth of microorganisms responsible for the infectious shrimp diseases which have spread through the farms in Southeast Asia in recent years.

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