Influence of fly ash on hydration compounds of high-volume fly ash concrete

Abstract

Development of sustainable materials has become one common goal across the globe to meet the ever-increasing demand for the construction materials. High volume fly ash (HVFA) concrete is one such sustainable construction material which utilizes fly ash in concrete as a partial replacement of cement. Though the existing literature focuses abundantly on high volume fly ash concrete, the present work aimed to explore the intricate hydration process thorough a systematic experimental program. A series of experiments including compressive strength, rapid chloride permeability, UPV, acid resistance, X-ray diffraction, SEM and EDAX were performed to examine the effect of varying proportions of fly ash (0%, 20%, 40%, 60%) on cement replacement. Analysis of results indicated formation of hydration compounds in the form of alite, belite, celite, portlandite and tobermorite (C-S-H gel). Results of mechanical and durability tests showed that, to achieve maximum benefits, cement can be replaced to an optimum value of fly ash of 40%. The authors believe that the formation of hydration compounds tobermorite and celite resulted in attaining enhanced durability and strength in high volume fly ash concrete.

Keywords

• hvfa concrete
• compressive strength
• rcpt
• upv
• acid resistance
• x-ray diffraction (xrd) and energy dispersion spectroscopy
• scanning electron microscopy