Fly ash is a well-known supplementary cementitious material that is the by-product of coal-fired thermal power plants. The contribution of fly ash to the enhancement of the mechanical and durability properties of cementitious materials has been documented in concrete technology for many years. In this study, to allow superior mechanical and durability properties, fly ash-based mixtures have been produced after optimization of particle size distribution (PSD) of Class F and Class C fly ash according to the formula of Fuller–Thompson. Different distribution modulus values ranging from 0.3 to 0.6 were used to achieve ideal PSD in accordance with the Fuller–Thompson equation. 30% of F- and C-class fly ash by weight of cement were used to replace with cement in cementitious composites by optimizing PSD with help of air jet sieve. The recommended optimization technique improved the 7-, 28- and 90-day compressive and flexural strength results of mortars. Compressive and flexural strength tests and rapid chloride permeability test of cement-based systems incorporating fly ash up to 15% replacement ratio with optimized PSD at 90-days exhibited better results than those of plain samples owing to the filler effect.
In this study, the effect of sample preparation on the content of clay particles was investigated. Monoionic forms of bentonite from Slovakia were used in an experimental programme. The samples were tested by laser diffraction. The analysis of the results was conducted using the Helos H 2398 SUCEL. The preparation of samples has a significant influence on particle size distribution. The most similar results to those of the areometric analysis were obtained when tests are carried out directly after the preparation of samples by means of the Calgon disperser simultaneously with a mechanical stirrer. This paper was presented at seminar for Ph.D. candidates at Kielce University of Technology.
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