Doctoral Dissertations

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.


Zoughi, R.
Donnell, Kristen M.

Committee Member(s)

Fan, Jun, 1971-
Kurtis, Kimberly E.
Stanley, R. Joe


Electrical and Computer Engineering

Degree Name

Ph. D. in Electrical Engineering


National Science Foundation (U.S.)


Funded by the National Science Foundation under award No. 1234151


Missouri University of Science and Technology

Publication Date

Spring 2016

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

Note about bibliography

Includes bibliographic references.


© 2016 Ashkan Hashemi, All rights reserved.

Document Type

Dissertation - Open Access

File Type




Subject Headings

Alkali-aggregate reactions
Concrete -- Deterioration
Dielectric measurements
Nondestructive testing
Microwave measurements
Reaction mechanisms (Chemistry)

Thesis Number

T 10911

Electronic OCLC #