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Title: Bottom Ash for Use as a Pozzolan in Concrete

Author(s): Cole Spencer

Publication: Web Session



Appears on pages(s):



Date: 4/1/2021

In modern construction it has become standard practice for structural concrete to contain at least one supplementary cementitious material (SCM). This practice has been adopted due to the tangible improvements in durability and cost-efficiency associated with such concrete. However, recent regional and seasonal supply shortages of ordinarily available SCMs, along with increasing variability in SCM quality, have prompted research into previously untapped sources of pozzolanic material. One such candidate to help fulfill this need is pulverized coal bottom ash. Coal bottom ash is a byproduct of coal combustion, and unlike fly ash, has yet to be employed as an SCM within the cement and concrete industry. While previously overlooked due to inherent processing requirements, growth in demand for readily sourced SCMs has provided the motivation to begin researching this untapped resource. This work seeks to investigate the useability of coal bottom ash as an SCM by examining its physical and chemical properties, its performance in cementitious systems in terms of ASR-mitigation, pozzolanic reactivity, and impact on set time, and how that performance compares to fly ash. Additionally, the importance of processing is considered by evaluating the performance of the same coal bottom ashes milled to varying degrees of fineness.