| Abstract: | Increasing environmental concerns arising from concrete's high energy consumption and carbon dioxide emissions is generating an interest in improvements in concrete durability, partial replacement of ordinary Portland cement, or creation of new binder chemistries. Cements based on bonds between magnesium and silicon, also found in nature, are less explored and their utilization in construction applications is limited, in part because of insufficient data ascertaining the kinetics of precipitation and the structural mechanisms for strengthening. In this study, in situ and ex situ experiments using atomic force microscopy with mineral substrates (mica, periclase) were performed to produce magnesium silicate hydrates (MSH). The environmental conditions including the magnesium/silicon molar concentration ratios, temperatures (25°-50°C), and reaction durations (1-40 hours) were varied to study their influence on morphology and growth rates of MSH. The MSH precipitates were analyzed using Fourier-transform infrared spectroscopy, Raman spectroscopy, and scanning electron microscopy with energy dispersive X-ray spectroscopy to ascertain their chemical composition. The insights gained from this study will enable the precise chemical synthesis of MSH from abundant magnesium-rich solids and brines, leading to the widespread use of MSH as a binder material for construction purposes and an alternative to ordinary Portland cement. |