Study on Properties of Concrete with Ultra-Fine Particles Produced From Fly Ash

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Title: Study on Properties of Concrete with Ultra-Fine Particles Produced From Fly Ash

Author(s): Y. MatsufujiI

Publication: Special Publication

Volume: 132

Issue:

Appears on pages(s): 351-366

Keywords: compressive strength; concretes; fly ash; silica; strength; ultra-fine particles; water-reducing agents; Materials Research

Date: 5/1/1992

Abstract:
Describes the basic properties of concrete containing ultrafine particles, which are produced from fly ash. The ultrafine particles are produced from fly ash with ultra-high temperature treatment. This treatment enables control of the specific surface area, from 20 to 130 mý/g, by controlling the quenching speed. The main chemical component is SiO2, over 60 percent of which is amorphous. Ignition loss, which is 1 to 5 percent with fly ash, is below 0.2 percent. The properties of concrete with these ultrafine particles differ greatly in the specific surface area of the particles. Experiments showed that ultrafine particles with a specific surface area of 71 mý/g develop a compressive strength of approximately 118 MPa (w/c = 25 percent), while plain concrete develops approximately 105 MPa. Ultrafine particles with a specific surface area of 35 mý/g improve the consistency of fresh concrete, especially in a low water/cement (w/c = 20 to 25 percent), enabling concrete to be easily mixed without increasing the dosage of high-range air-entraining (AE) water reducer. Results show ultrafine particles to be highly active and useful as an admix material for high strength concrete.