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SP-178 This Symposium Publication contains the proceedings of the Fourth CANMET/ACI/JCI International Conference held in Tokushima, Japan, in June 1998. Sixty-two refereed papers were accepted for presentation at this conference and for this publication.

A pressurized fluidized bed combustion thermal power plant (PFBC) is a coal-fired thermal s ecially for the enhancement ower plant developed e ficiency and generating the reduction of environmental loads. The physicochemical properties of coal ash produced from this type of power plant (PFBC ash) are different from those of ordinary fly ash, because coal is mixed with crushed limestone and burned at a lower temperature than that in the conventional power generation system. This study explores the feasibility of utilizing PFBC ash as a concrete admixture. It has been found that the coal ash from a secondary cyclone dust collector enhances the strength of concrete a though it cannot improve the fluidity. of chemical anal ses A variety why the coal as were carried out to explain the reason so produced has such effects. The fly ash obtained from a secondary cyclone dust collector was found to enhance mortar strength due to the hydration of sulfur. containing minerals such as gy sum reaction of fine-grain silica. Thus, tK and the pozzolanic concrete admixture has been verified. feasibility of using it as

Pozzolanic materials, either natural or artificial, have long demonstrated their effectiveness in producing high-performance concrete. Artificial pozzolans, such as fly ash and rice husk ash have gained acceptance as supplementary cementing materials in many parts of the world. Perhaps the latest addition to the pozzolanic ash family is palm oil fuel ash, a waste material obtained on burning of palm oil husk and shell in palm oil milling industry. This paper presents laboratory test results on the performance of palm oil fuel ash (POFA) in mortar and concrete containing the ash as a partial replacement of normal portland cement against sulfate attack. Mortar bars having dimensions of 25 x 25 x 2.50 mm, and 100 mm concrete cube specimens were cast with a fixed water-cementitious material ratio of 0.5 where normal Portland cement was replaced by 30% POFA by mass. After 28 days of moist curing the specimens were put into 10% sodium sulfate solution with alternate wetting and drying cycles. During the test period of over one year, the mortar bar specimens were periodically subjected to expansion measurements while the concrete cube specimens were tested for change in mass. Finally, examination of the deteriorated materials through X-ray diffraction analysis was carried out to elucidate the mechanism of deterioration. It has been observed that the specimens with POFA, in general, exhibited significantly higher resistance to the sulfate attack than those prepared with normal portland cement alone.

Using superplasticizers and additions, engineers can deal with a great range of materials combinations to design concrete. But one can never be sure that all the possible compositions will perform as well on site. For example, even with the same cement, the same plasticizer and the same initial slump, these compositions may not have the same slump loss. The testing of 47 ordinary concretes made with, different cement content, addition content (fly ash or limestone filler), superplasticizer content or effective water content. has shown, with the materials tested, that slump loss depends essentially on water content.

Recently, the amount of fly ash generated from electric power plants and other industries in Japan was about 6.4 million tones per year, and it is expected to increase to 12 million tones per year in 2010. Hence, there is a great need to investigate solutions on how to utilize fly ash more effectively. One of the promising solutions is to use high amounts of fly ash in concrete as replacement of the fine aggregate, instead of replacing portland cement. When replacing a part of the cement by a high amount of fly ash, changes in strength development and resistance to carbonation may cause problems in the applications of the concrete to actual building construction in respect to the structural and durability requirement. Though the replacement of a part of fine aggregate by fly ash reduces low strength development, higher rates of carbonation of the concrete may remain as a problem, as calcium hydroxide will be consumed by pozzolanic reaction with the fly ash.This study aims to clarify the effects of high level of replacement of fine aggregate by fly ash on the properties of concrete in the fresh state as well as in the hardened state, and investigate the limit of the replacement in view of the practical application of this type of concrete, Rheological properties, compressive strength and rate of carbonation of mortars of water to portland cement ratio of 0.3, 0.4 and 0.5 in which the fine aggregate was replaced with fly ash at 25 and 50 percent levels were evaluated experimentally. It was found that the rheological constants increased with higher replacement level of fly ash and that, when water to portland cement ratio was maintained the strength development and carbonation properties were improved.