Development of micromechanics models and innovative sensor technologies to evaluate internal frost damage of concrete

Document Type

Article

Publication Date

12-1-2011

Abstract

Internal frost damage is a major problem affecting the durability of concrete in cold regions. Micromechanics models and innovative sensor technologies were used to study the mechanisms of frost damage in concrete. Crystallization pressure resulting from ice nucleation within capillary pores is the primary cause of internal frost damage of concrete. Crystallization pressure of a cylinder pore was formulated with interface energy balance with thermodynamics analysis. Crystallization pressure on the pore wall was input for fracture simulation with the extended finite element model on a homogeneous beam sample with a vertical cylinder pore; this simulation led to a straight line. An image sample was obtained with imaging process and ellipse fitting techniques to capture microstructure of a tested specimen. Crack simulation of this image sample with the same cylinder pore under crystallization pressure matched fracture patterns of the single-edge-notched bending specimen. Extended finite element model simulation results were verified by open-mode fracture behavior in middle-notched single-edge-notched bending and freezing tests. An innovative time-domain reflectometry sensor was developed to nondestructively monitor the freezing process. Data show that sensor signals from time-domain reflectometry can detect the freezing degree, an important input parameter. Studies indicate that the micromechanics models and time-domain reflectometry sensor techniques can help practitioners evaluate internal frost damage of concrete. Future work will incorporate sensor measurements into micromechanics models to predict, in real time, internal frost damage process in concrete specimens. The goal of this study was to provide practical nondestructive testing and computational tools for designing concrete that is resistant to freezing damage.

Publication Title

Transportation Research Record

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