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Three kinds of inorganic mineral admixtures (silica fume, alumina-type mineral and fly ash) were mixed with cement and aggregates and having water-to(cement + condensed admixture) ratio using high-range water reducing agent. This study clarified both the properties of fresh concrete and adequate concrete mix proportions. This test was made by dividing eight factors and three levels among the orthogonal array of L27, based on test plan method. (1) Flowability using fly ash concrete and alumina-type mineral concrete is increased with increase in dosage of admixture, but that of silica fume concrete is decreased. (2) In order that concrete slump with various admixtures have the same flowability at a slump of 18cm (for concrete without admixture), at a certain dosage of admixture (X1.6), the slump value is about 21cm with silica fume concrete, about 6cm with fly ash concrete and about 16cm with alumina-type mineral concrete. (3) Fly ash concrete and alumina-type mineral concrete show more segregation of aggregate. Silica fume concrete shows less with the passage of time. (4) Unit water content for all cements and aggregates can be determined by ordinary mix proportion. (5) Air-entraining-agent content required to get the same air content increases with increase in the amount of mineral admixture and superplasticizer.

This paper presents the results of an experimental investigtion on the behavior of slurry infiltrated fiber concrete (SIFCON) prisms (beams) subjected to static and cyclic flexural loading. Altogether, 60 prism specimens were tested. The main objective of this investigation was to study the influence of fiber length, fiber volume and silica fume on the strength and ductility of SIFCON under static and cyclic flexural loading. The fibers used were steel fibers with hooked ends. The volume content of fibers varied from 4 percent to 12 percent. The fiber lengths were 30 mm, 40 mm, 50 mm and 60 mm. The slurry was made with and without silica fume. A high-range water reducing admixture (superplastisizer) was used in order to obtain a flowing slurry. The water/cement ratio was maintained at 0.30. The cube strength of slurry with silica fume averaged to 10.36 ksi (71.43 MPa). The slurry without silica fume had an average cube strength of 7.86 k s i (5 4 .2 0 MPa). The results of this investigation indicate that a very high flexural strength, in the order of 10,000 psi (69 MPa) can be obtained using SIFCON. The prisms (beams) are extremely ductile both under static and cyclic loading. The addition of silica fume increases the flexural strength. The percentage (magnitude) of increase is the same as the increase in the compressive strength of the slurry. Silica fume has no noticeable effect on the ductility of the beams.

The effects of the partial replacement of portland cement in grouts with condensed silica fume were studied. Initial experiments examinedthe fluid properties of fresh grouts, using concentric cylinder viscometry. An effective mixing procedure using a high-shear mixer was developed Replacements of up to 20% of the cement by silica fume and with water- solids ratios of 0.3 to 0.6 were examined. Two commercially available superplasticers were used - a sulphonated melamine and a sulphonated naphthalene formaldehyde. To maintain fluidity the admixture dosage needs to be increased approximately proportionally to the silica fume content. The grouts are thixotropic and more stable than plain OPC grouts. The silica fume leads to an enhanced alite peak in the rate off heat output during hydration, but the use of the superplasticiser leads to a masking of changes of the time to the peak. Compressive strength at one day and from three days onwards is increased by incorporating condensed silica fume, with greater proportional effects being obtained at higher water-solids ratios . Dynamic elastic modulus values do not show the same increase, and for equal strengths, grouts containing condensed silica fume are less tiff

An expansive grout, based on Class H cement, an expan- sive admixture consisting essentially of plaster of paris (calcium sulfate hemihydrate), and a Class C fly ash, was proportioned for use underground. Specimens of this grout, and of five modified versions of it, were tested to determine the effects of using two ther fly ashes, with or without silica fume, on compressive strength, volume change, phase composition, and microstructure. Properties were monitored to 960-days age. Up to 365-days age, specimens of the mixture modified with Class F fly ash had lower compressive strengths and generally more expansion than did those of the original composition. At ages of 90 days and greater, the same was true of samples prepared with a second Class C fly ash. Substitution of silica fume for 5 or 10 percent of the cement gave higher early strength, but the combination of the second Class C fly ash and 10 percent silica fume gave the lowest strengths at ages of 90 days and greater. Despite the substitutions, properties were markedly similar, compressive strength from all modifications exceeded 90 MPa at 365 days, and phase composition and microstructures became more similar with time.

This paper describes an investigation of the use of industrial by-products such as bottom ash and silica fume with high silica content, as the admixture for mortar and concrete. The bottom ash used for this investigation was ground in a ball mill. At first, basic tests using mortars were conducted. Subsequently, the concretes containing different proportions of the two by-products were tested for strength development under accelerated curing, drying shrinkage, and water permeability. The results of the mortar strength tests indicate that the proper amount of ground bottom ash is about 5 percent if used to replace cement or 10 percent if used in addition to cement, and that of silica fume is approximately from 5 to 10 percent if used to replace cement and from 10 to 15 percent if used in addition to cement. When steam curing and autoclave curing are used, the concretes containing ground bottom ash and silica fume have higher early compressive strength than concrete without these materials. The coefficients of water permeability of the concretes using ground bottom ash and silica fume are lower than those of concrete without these materials. Paticularly, the water-tightness of silica fume concrete improved remarkably, although the concrete has a little higher drying shrinkage in comparison with concrete without silica fume. The use of these materials in amount of 5 to 10 percent to replace cement is effective for the improvement of concrete properties.