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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.

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

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.

Among the major problems facing the concrete industry at the end of the twentieth century are the enormous infrastructural needs of a rapidly urbanizing world, the premature deterioration of many concrete structures, the need to improve concrete durability in a cost-effective way, and increasing public interest in finding ecological solutions for safe disposal of millions of tons of industrial by-products that might be suitable for incorporation into cementitious materials and concrete. In this paper the author has shown that all these problems are interrelated and can be resolved by adopting a holistic approach.

Waste materials may be upgraded to specification standards and occasionally to premium materials for use in the preparation of composites or for use in their own. The treatment for upgrading is a matter of cost and of the potential environmental problems that the treatment can create. The investigation presented in this paper shows an example of the improvements of fly ash properties achieved by a simple physical process, that is, air cyclone separation. This process gives a very line ash with adequate pozzolanic activity and is suitable for producing high performance concrete with excellent durability particularly when exposed to aggressive environments. The paper presents data on the properties of the fine fly ash including lime reactivity, composition, size distribution and shape. The investigation was carried out using two fly ashes obtained by the process of air separation using a prototype small air cyclone separator and an air mini-splitter. The properties of these ashes were compared to the properties of the original raw ash and with the properties of a fly ash processed industrially by the conventional mechanical separation process, which produces a fly ash conforming to the appropriate British specifications for use in the production of structural concrete. In this test programme, high performance concrete made with 0.3 fly ash and 0.7 ordinary Portland cement (by weight) as binder was assessed by measuring strength, porosity, and permeability. These properties were used to evaluate the performance of concrete and potential long term durability.