Ngugen, Thang Duc (1996) Development of silane / siloxane emulsions for application in building protection. PhD thesis, Victoria University of Technology.

Abstract

Novel silane/siloxane emulsions for rendering concrete surfaces water repellent have been developed and patented. These novel emulsions were prepared from alkylalkoxysilanes as the base materials. One novel emulsion was composed of an alkylalkoxysilane and a neutralised polyisobutylsiloxane latex. The latex was prepared by the emulsion polymerisation of commercial isobutyltrimethoxysilane. The other novel emulsion was prepared by ·emulsification of a mixture of a silicone fluid and an alkylalkoxysilane in water with an amine soap as surfactant. A particular amine soap was chosen as a deactivatable surfactant to deliver very little negative beading effect at the surface of the substrate. The emulsions developed in this research contain no solvent. Therefore they comply with various regulations regarding volatile organic content (VOC). They are non-toxic and non-flammable, and may be considered as environmentally friendly materials. The novel silane/siloxane emulsions were prepared as concentrates which can be transported and then diluted on site with water for application. They are stable and storable as concentrates over a long period of time. The emulsions are effectively neutral and maintain a high level of original alkylalkoxysilane on long term storage. Experimental results indicated that the emulsions developed by the method of this research were very effective for concrete protection due to their high penetrating power, their stability to the alkaline environment and their ability to protect concrete from the intrusion of water and chloride ion. Their performance was comparable to solvent-based products in terms of stability, beading effect, penetration depth, water repellency, alkali resistance, UV resistance and the efflorescence resistance of the treated concrete. The mechanism of the emulsion polymerisation process of isobutyltrimethoxysilane, the characteristics of the polyisobutylsiloxane latex and the properties of the novel silane/siloxane emulsions were studied in this research.

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