Evaluation of pozzolanic activity of fly ash by direct and indirect methods

Abstract

     Physical and chemical characteristics of fly ash depend on the origin of the coal as well as itscombustion technology in the power plant. Thus, chemical, mineralogical, physical and activitycharacterizations of the fly ash were considered to evaluate. In this research, two test methods(direct method and indirect method) have been used to assess the pozzolanic activity of fly ash, andthe results from each test is correlated with each other. The direct method was thethermogravimetric analysis test by measuring reacted calcium hydroxide content and the indirectmethod used was the compressive strength activity index test. The obtained results showed that,experimental criterias of the fly ash studied conforming to the requirements of activity mineraladmixture - fly ash for concrete, mortar and cement according to standard TCVN 10302: 2014;Contemporaneously, results of the direct method are the basis for explaining the effect of fly ash inthe development compressive strength by indirect method through the puzzolanic effect.