International Concrete Abstracts Portal

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

Canada Centre for Mineral and Energy Technology (CANMET) has an ongoing project dealing with the role of supplementary cementing materials in concrete. As a part of this program, a new type of concrete known as high-volume fly ash concrete has been developed. In this type of concrete, the water and cement contents are kept very low, i.e. about 115 and 155 kg/n?, respectively, and the proportion of low-calcium fly ash is about 56 per cent of the total cementitious materials. This type of concrete has excellent mechanical properties and durability characteristics. The objective of this study was to investigate the application of the high-volume fly ash system to the production of structural lightweight concrete. In this study, high-volume fly ash concrete mixtures were made using ASTM Type I portland cement, fly ashes from sources in the U.S.A. and lightweight coarse aggregates from four different producers, three from the U.S.A., and one from the U.K. A reference concrete mixture without fly ash was also made for comparison purposes. A large number of test specimens were cast to determine the mechanical properties and durability characteristics of the concrete. The test results show that the structural high-volume fly ash concrete had mechanical properties similar to those of the reference concrete. The fly ash concrete generated significantly less heat of hydration, and showed noticeably better resistance to chloride-ion penetration than the reference concrete of similar 2%day strength. All concretes investigated demonstrated an excellent resistance to the freezing and thawing cycling

A large proportion of concrete placed in Australia contains one or more supplementary cementing materials (SCM’s; either fly ash, ground granulated blast-furnace slag or silica fume). Despite this, specifications for technically advanced projects often restrict their use even though Australian research data justifying their application dates back to the early 1960’s for fly ash and slag, and the early 1970’s for silica fume. World-wide research on SCM’s in concrete dates back even longer. It is the task of the researcher together with the technical marketer to provide effective transfer of this knowledge to the specifier. In most cases, the specifier is either a civil or structural consultant, or a design team within a major public authority or contracting firm. The specifier increasingly needs to seek up-to-date knowledge in concrete technology, a task that is ever more difficult with imposed time constraints. This study maps the processes whereby research and development data are put into practice. A three-stage process is used to investigate this. First, measurements of the technology transfer process are obtained through targeted surveys of concrete specifiers with the objective of determining their attitudes and knowledge regarding SCM’s Second, recent Australian specifications for SCM concrete comprising Standards, Codes of Practice and selected project specifications are reviewed. Third, the data generated is examined to highlight present shortcomings in the technology transfer process in Australia, specifically relating to the use of SCM’s. It is concluded that many project specifications with respect to the use of SCM’s in concrete can be significantly improved from the standpoint of the supplier, the specifier and the facility owner. This can be facilitated through improved technology transfer. Discussion in the paper focuses on increasing the efficiency of the process for taking research into field application.

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.