Development of Nano-Modified Concrete for Next Generation of Storage Systems
The goal of the research was to develop a superior concrete for the long-term storage of used nuclear fuel by engineering concrete at the nanoscale through the incorporation of nano-sized and nano-structured particles based on enhanced reactivity (not fiber reinforcement). The specific objectives were to determine for nano-modified concrete: 1. The effects of environmental weathering (i.e., wet/dry and ingress of reactive species such as chloride and sulfate from the marine environment or other sources) and exposure to radiation and thermal environments on the structural stability and microstructural evolution of the material; 2. How microstructural and morphological changes from environmental weathering and thermal and radiation damage affect the long-term, macroscale performance of the material; and, 3. Identify formulation envelopes for nanoparticle content and combinations to achieve superior concrete criteria for dry storage systems by integrating and extending existing predictive modeling approaches that couple reactive transport and thermo- chemo- and radiation induced damage. The major findings of this work are summarized as follows. The results are being processed and compiled in manuscripts for peer-reviewed publication. Due to the late access to the gamma irradiation facility, material characterization is continuing. Dispersion/agglomeration of nanoparticles in cement pastes. The dispersion/agglomeration of nanoparticles (NPs) of SiO 2 , TiO 2 , Al 2 O 3 , Fe 2 O 3 , and clay (bentonite and halloysite) in water, with and without polycarboxylate-based high range water reducer (P-HRWR), and in the environment of hydrating cement have been investigated. The intrinsic particle characteristics, surface charge, pH, monovalent and divalent ion concentrations in solution, and modes of interaction of the NPs with P-HRWR influenced the NP behavior in solution.