Dissertation
CHARACTERIZATION OF CHLORIDE DIFFUSIVITY, MOISTURE DIFFUSIVITY, AND DRYING SHRINKAGE OF MORTAR AS A FUNCTION OF PORE SYSTEM PARAMETERS
Doctor of Philosophy (PhD), Washington State University
01/2018
Handle:
https://hdl.handle.net/2376/16411
Abstract
The importance of satisfactory durability performance of cement-based materials (CbM) has been recently recognized. As durability distresses typically involve the transfer of water and ions through the pore system, transport properties and pore system parameters determine the durability of CbM. Methods to directly probe these properties are complex and costly; therefore, nondestructive electrical conductivity (σeff) tests deserve investigation as effective alternative methods. To confirm the predictive capabilities of electrical techniques, correlations between σeff and the pore system and transport properties need to be explored.
To address this need, time-dependent tortuosity via Archie’s exponent (m) and formation factor (FF) of 12 mortar mixtures were evaluated using embedded σeff sensors, and correlated with transport properties, chloride diffusivity (DCl) and apparent moisture diffusivity (Da). Using internal relative humidity (h-) profiles two Da(h) models from the literature were optimized. The evaluated Da was used for the poromechanistic computation of drying shrinkage strains (εsh).
The results highlight the usefulness of decrease in water-to-cementitious materials ratio (w/cm) and implementation of supplementary cementitious materials (SCM) to increase pore system intricacy and reduce transport properties. These improvements are evident in increase in m and FF, decrease in DCl and Da, slower drying process, and lower drying shrinkage. To assess the durability of SCM mixtures, in addition to total porosity, other properties such as FF and m should be considered. Strong correlations between m and increase in pore system refinement and non-uniformity of pore sizes inferred from theoretical pore size distributions are identified. Even though Da(h) models include three or four calibration parameters, the parameters that define the transition in Da from liquid- to vapor-dominated transport are found as the most influential. Such parameters exhibit strong correlations with tortuosity. A new procedure to establish the equivalent temperature gradients due to shrinkage (ETGsh) for concrete pavements in four climatic regions using poromechanistic approach was developed as an alternative to the corresponding PavementME design procedure. The proposed module is substantially more sensitive to mixture design parameters and exposure environment compared to PavementME default predictions, signifying the potential for improvements in the current design methodology.
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Details
- Title
- CHARACTERIZATION OF CHLORIDE DIFFUSIVITY, MOISTURE DIFFUSIVITY, AND DRYING SHRINKAGE OF MORTAR AS A FUNCTION OF PORE SYSTEM PARAMETERS
- Creators
- Milena Rangelov
- Contributors
- Somayeh Nassiri (Advisor)Balasingam Muhunthan (Committee Member)Xianming Shi (Committee Member)Nicholas Engdahl (Committee Member)Timothy Ginn (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Civil and Environmental Engineering
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 232
- Identifiers
- 99900581622301842
- Language
- English
- Resource Type
- Dissertation