Title:
Using a Combined CT Scan/Scanning Electron Microscope (SEM/EDX) Protocol to Appraise and Better Understand ASR-Induced Expansion and Deterioration in Concrete
Author(s):
Leandro Sanchez
Publication:
Web Session
Volume:
ws_F23_LeandroSanchez.pdf
Issue:
Appears on pages(s):
Keywords:
DOI:
Date:
10/29/2023
Abstract:
Alkali-silica reaction (ASR) is among the most harmful deterioration mechanisms affecting concrete infrastructure worldwide. ASR is a chemical reaction between the alkali-hydroxides from the concrete pore solution (i.e., Na+, K+ and OH-) and certain unstable mineral phases from the aggregates used to make concrete. ASR generates a secondary product, the so-called ASR gel, which swells upon moisture uptake from the surrounding environment, leading to induced expansion and deterioration of the affected concrete. Over the years, several research programs were conducted with the aim of better understand the mechanism leading to ASR-gel formation and inducing expansion and deterioration. Some microscopic (i.e., scanning electron microscope – SEM coupled with energy dispersive x-ray analysis - EDX, damage rating index – DRI, etc.) and mechanical procedures (i.e., stiffness damage test – SDT, dynamic and static modulus of elasticity - ME) were found suitable to explain ASR-gel formation, along with ASR-induced crack generation/propagation and their implications on the mechanical properties of affected concrete. However, most of those tools have only demonstrated a “portion” of the whole deterioration process since the microscopic tools aforementioned are run on 2D polished sections from selected locations of the affected material while the mechanical procedures do not directly correlate performance with inner microstructure degradation. In this work, one aims to combine 3D-CT scan and SEM/EDX analyses in concrete incorporating highly reactive aggregates (i.e., Springhill coarse aggregate) and doped with barite and cesium nitrate as tracers to detect and follow ASR-gel formation as a function of induced expansion. Thus, concrete specimens containing the above products will be fabricated and stored under conditions (i.e., soaked into 0.4M at 60C) enabling ASR-induced expansion and deterioration.