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The purpose of this study was to determine the water permeability of high slag content concrete(HSCC) incorporating large amounts of ground granulated blast-furnace slag (GGBS) of high fineness. The main variables are the replacement level of slag, the fineness of slag and the type of chemical admixtures. The slag content in cement ranged from 0 to 95 percent by weight of total cementitious materials and the fineness of slag ranged from 404 to 1200 m2 /kg. Within the range of this study, the following results were obtained: 1 . The coefficient of water permeability of high slag content (HSC) concrete increased as the content of ground granulated blast-furnace slag(GGBS) was increased. However the water tightness of HSC concretes could be improved by utilizing high fineness slag within the range of 1200 m2/kg, and was further improved by utilizing an air entraining and high range water reducing (AEHW) admixture. 2. Both the total porosity and mean diameter of pores increased by raising the slag content, but decreased as the fineness of slag increased. The water permeability of HSC concretes was closely related to the porosity, with the diameter over the certain threshold value, rather than to the mean diameter of pores.

Effect and mechanism of natural zeolite(NZ) on preventing expansion due to ASR are studied in this paper. The reduction of deleterious expansion by NZ is compared with that of three other cementitious materials: silica fume(SF), fly ash(FA), and blast-fhrnace slag(BFS). The order of effectiveness is SF>NZ>FA>BFS. When 30% zeolite blended cement with an alkali content of 1.82% NazO equivalent is used in concrete, there will be no damage from ASR even ifall the aggregates are reactive. The suppression of ASR by NZ is related to its fineness. The required dosage of NZ is about 20% at a surface area of 7000 cm2/g, and decreases to 15% at 9000 cm’lg with the same effect. Pre-heating of NZ at 500 ‘C increases the preventive effectiveness. The suppressing mechanism of NZ on ASR is decreasing the alkali ion concentration in the pore solution in concrete through ion exchange, adsorption, and pozzolanic reaction of NZ. So the formation of alkali silicate is prevented and the interface is improved.

This paper presents developments in electrical impedance methods to study hydration and reaction kinetics of alkali activated slags and fly ash at room temperature (i.e. 21°C). To highlight the testing methodology, work focuses on monitoring the temporal change in both conductance and capacitance of a typical slag and low-lime fly ash activated with calcium hydroxide. Measurements were taken over time scales extending up to six days hydration. It is also shown that the measured electrical parameters change markedly with frequency of applied electrical field. The latter was found particularly relevant to capacitance measurements.

This report presents the properties of hardened super workable concrete in which ground granulated blast furnace slag was used, and compare these properties with the corresponding properties of ordinary concrete. Two ground granulated blast furnace slags of fineness 4500 cm2/g and 6150 cm2/g were used for this research. The replacement ratio of cement by blast furnace slag were controlled to O%, 30%, 5O%, and 70%. The concrete specimens were cured by four different methods; in air continuously, in water for 3 days and then in air, in water for 7 days and then in air and in water continuously. The super workable concretes, which were cured in water suffciently at early ages, exhibited higher performance in compressive strength, water permeability, resistance to freezing and thawing and carbonation in comparison with ordinary concrete. As for the porosity as well, the total pore volume of these concrete were lower than that of ordinary concrete. This excellent performance was more remarkable in the super workable concrete with BFS of fineness of 6000 cm2/g. But, these properties of: super workable concrete with BFS were more sensitive to initial water curing period than the concrete without BFS.

Various grades of portland blast furnace slag cement (PBFC) and normal portland cement (OPC) concrete have been cured under adiabatic and semi-temperature matched curing conditions. Comparisons of the compressive strength between adiabatic, semi-temperature matched and ambient cured concrete have been made. The results indicated that the curing history had significant influence on the compressive strength development and the in-situ early strength of PBFC concrete is comparable to the same grade of OPC concrete after three days. The high curing temperature (above 65°C) reduced the later-age strength both for PBFC and OPC concrete. The durability of the concrete cured under various conditions was also evaluated by rapid chloride permeability test.