Microstructural Analysis of Concrete Using Cow Bone Ash for Alkali-Silica Reaction (ASR) Suppression
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Date
2020
Journal Title
Journal ISSN
Volume Title
Publisher
Journal of Casting & Materials Engineering
Abstract
Concrete pavements are prone to microstructural changes and deterioration when exposed to Alkali-Silica Reaction (ASR). ASR
results in strength reduction, cracking, spalling and other defects in the concrete if left unchecked. Supplementary Cementitious
Materials (SCMs) such as Cow Bone Ash (CBA) however can be used to improve concrete performance, hence its use in this
study. Concrete samples were prepared at replacement levels of 0%, 5%, 10%, 15%, 20% and 30% of cement with Cow Bone
Ash. The concrete samples were then subjected to petrographic and Scanning Electron Microscopy (SEM) analysis. Petrographic
examination shows that the minimal and least amount of ASR gels and micro cracking were observed at 15% CBA replacement
of cement in the concrete samples. Scanning Electron Microscopy (SEM) analysis shows that changes in the elemental composition
of the concrete samples is related to the effect of CBA which enhances adhesion in the concrete. SEM analysis show that, in
general, the change in microstructure in the concrete was mainly due to the change in the arrangement of the C-H-S compounds.
The microstructure analysis indicates that CBA in concrete influences the densification of the concrete at the transition zone,
resulting in a much lower porosity. This results in the concrete having a tightly bound layer that repels ingress of water and
thereby inhibiting cracks and gel formation as water is a contributing factor to the ASR in concrete.
Description
Staff Publication
Keywords
petrographic analysis,, Scanning Electron Microscopy,, Cow Bone Ash,, Alkali-Silica Reaction,, concrete pavement