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Development of Inorganic Silicone Polymers from Silica Fume

Geopolymers, inorganic materials with polymer-like repeating units containing silicon, aluminum, and oxygen, in 1-, 2-, or 3-dimensions, have been gaining popularity. While most research has focused on rigid, higher- strength geopolymers with mechanical properties similar to those of Portland cement concrete, there also exists a silicon-rich class of geopolymers which is more polymer-like, with lower strength and stiffness, and greater strain capacity but still having thermal resistance much superior to traditional carbon polymers. Several industrial wastes are rich in silicon. Depending on various properties of the waste such as such as crystallinity, the actual compounds in which the silicon exists, and the presence of minor compounds, they can be "activated" thermochemically, using alkaline solutions and low-temperature oven curing to obtain inorganic polymers. Silica fume is one example. In this work, a few selected mixtures are presented to discuss the influence of varying the alkalinity the chemical activator (sodium hydroxide) and varying the thermal curing parameters (temperature and duration) on the properties of the polymer obtained. Polymers, softer and harder, porous and non-porous, with contrasting properties which can be useful for different construction applications are developed. Some mechanical and physical properties of these polymers, and their resistance to moisture is discussed.