Keywords and Phrases
Cement-based materials; Dielectric mixing model; Microwave nondestructive techniques
"Since alkali-silica reaction (ASR) was recognized as a durability challenge in cement-based materials over 70 years ago, numerous methods have been utilized to prevent, detect, and mitigate this issue. However, quantifying the amount of produced ASR byproducts (i.e., ASR gel) in-service is still of great interest in the infrastructure industry. The overarching objective of this dissertation is to bring a new understanding to the fundamentals of ASR formation from a microwave dielectric property characterization point-of-view, and more importantly, to investigate the potential for devising a microwave nondestructive testing approach for ASR gel detection and evaluation. To this end, a comprehensive dielectric mixing model was developed with the potential for predicting the effective dielectric constant of mortar samples with and without the presence of ASR gel. To provide pertinent inputs to the model, critical factors on the influence of ASR gel formation on dielectric and reflection properties of several mortar samples were investigated at R, S, and X-band. Effects of humidity, alkali content, and long-term curing conditions on ASR-prone mortars were also investigated. Additionally, dielectric properties of chemically different synthetic ASR gel were also determined. All of these, collectively, served as critical inputs to the mixing model.
The resulting developed dielectric mixing model has the potential to be further utilized to quantify the amount of produced ASR gel in cement-based materials. This methodology, once becomes more mature, will bring new insight to the ASR reaction, allowing for advancements in design, detection and mitigation of ASR, and eventually has the potential to become a method-of-choice for in-situ infrastructure health-monitoring of existing structures"--Abstract, page v.
Donnell, Kristen M.
Fan, Jun, 1971-
Kurtis, Kimberly E.
Stanley, R. Joe
Electrical and Computer Engineering
Ph. D. in Electrical Engineering
National Science Foundation (U.S.)
Missouri University of Science and Technology
Journal article titles appearing in thesis/dissertation
- Comparison of alkali-silica reaction gel behavior in mortar at microwave frequencies
- Effect of humidity on dielectric properties of mortars with alkali-silica reaction (ASR) gel
- Effect of alkali addition on microwave dielectric properties of mortars
- Curing conditions effects on long-term dielectric properties of mortar samples containing ASR gel
- Microwave dielectric properties measurements of sodium and potassium water glasses
- Empirical multi-phase dielectric mixing model for mortars containing alkali-silica reaction (ASR) gel
xiii, 173 pages
© 2016 Ashkan Hashemi, All rights reserved.
Dissertation - Open Access
Concrete -- Deterioration
Reaction mechanisms (Chemistry)
Electronic OCLC #
Hashemi, Ashkan, "Microwave material characterization of alkali-silica reaction (ASR) gel in cementitious materials" (2016). Doctoral Dissertations. 2475.