UC Berkeley

The transport and adsorption phenomena in cement-based materials are the most important processes in the durability of concrete structures or nuclear waste containers, as they are precursors to a number of deterioration processes such as chloride-induced corrosion, sulfate attack, carbonation, etc. Despite this importance, our understanding of these processes remains limited because the pore structure and composition of concrete are complex. In addition, the range of the pore sizes, from nanometers to millimeters, requires the multi-scale modeling of the transport and adsorption processes. Among the various environments that cement-based materials are exposed to, aqueous and saline environments represent the most common types. Therefore, this dissertation investigates the adsorption and transport phenomena of cement-based materials exposed to an aqueous and saline environment from atomic to macro-scales using different arrays of novel spectroscopic techniques and simulation methods, such as scanning transmission X-ray microscopy (STXM), X-ray absorption near edge structure (XANES), molecular dynamics (MD), and finite element method (FEM). The structure and transport of water molecules through interlayer spacing of tobermorite was investigated using MD simulations because the interlayer water of calcium silicate hydrate (C-S-H) gel influences various material properties of concrete. The adsorption processes of cementitious phases interacting with sodium and chloride ions at the nano-scale were identified using STXM and XANES measurements. A mathematical model and FEM procedure were developed to identify the effect of surface treatments at macro-scale on ionic transport phenomena of surface-treated concrete. Finally, this dissertation introduced a new material, calcined layered double hydroxide (CLDH), to prevent chloride-induced deterioration.