Date of Award

12-2017

Degree Type

Thesis

Degree Name

Master of Science

Major

Civil Engineering

Major Professor

Z. John Ma

Committee Members

Khalid Alshibli, Yann Le Pape

Abstract

The understanding of irradiation effects on concrete has become urgent due to the possible extension of the operating life of nuclear power plants. Although there are scarcity, uncertainties, and inconsistency in concrete irradiation data, literature indicated that significant reduction in concrete mechanical properties occurred mainly due to the radiation-induced volumetric expansion (RIVE) of aggregate at neutron fluence of 1.0x1019 n.cm-2 (Energy > 10 KeV). This fluence is expected to be reached at 80 years of operation. Therefore, better understanding of aggregate RIVE could be obtained through understanding the RIVE of its mineral composition.A large amount of minerals and aggregates RIVE data were published recently in Russia, and reanalyzed by: (1) finding empirical models for minerals RIVEs; (2) upscaling minerals RIVEs to aggregate scale through homogenization; (3) comparing the upscaled and experimental RIVEs of aggregates to estimate crackings in them.Minerals empirical models were obtained by combining two different interpolation techniques with 90% confidence of RIVE estimation. Further analysis of minerals RIVEs indicated that silicate minerals have the highest RIVEs, and show different susceptibility to irradiation depending on: (1) the dimensionality of SiO4 polymerization; (2) the relative number of Si-O bond per unit cell; and (3) the relative bonding energy of unit cell.The upscaled RIVEs of aggregates were calculated at the same irradiation temperature (T) and neutron fluence (©) of experimental RIVEs. The Inverse Distance Weighting interpolation technique was used to normalize RIVEs at different conditions to a fixed condition of © Æ 1.0x1020n.cm-2 (E > 10 KeV), and T Æ 80±C. A comparison of the two RIVEs showed that mineral composition and texture play a major role in RIVEs of aggregates. RIVEs of silicate-bearing aggregates were higher than RIVEs of carbonate-bearing aggregates. For all aggregates, high plagioclase feldspar content, medium-to-large mineral grain sizes, or both, have higher cracks in experimental RIVEs than other aggregates with similar mineral composition. Further observations indicated igneous intrusive aggregates have high RIVEs that might be due to residual strains stored in those aggregates during their formation under high pressure and temperature.

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