Development and Characterization of High Performance Fibre Reinforced Cement Based Foams

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Cement based foams with density between 300-800 kg/m3 are used most commonly as non-structural fillers and geothermal insulation, and are particularly employed for their low density and ease of flow. However, this class of controlled low strength and ultra-lightweight cement based composites have not been well characterized, especially for applications in the extreme cold of Canada's north. Additionally, the combination of high cement content and high porosity leads to a wide range of durability issues, including shrinkage cracking, early age heat generation and poor resistance to sulphate attack. Further, as Portland cement undergoes hydration, the evolution of the internal cellular structure leads to thermal properties that are inherently time-dependent. Besides the non-structural applications currently underway in Canada, there exists tremendous potential for cement based foams in crash cushions and to resist liquefaction during earthquakes. However, its use in shock absorption is hindered by the lack of even the most basic high strain rate characterization, unlike the database on other brittle cellular solids. In order to utilize the benefits from its superior rheology, cellular structure and thermal resistance, cement based foams must be i) toughened and ii) rendered durable, with the accompanied quantification of its mechanical, rheological, thermal and transport properties under variable loading rates and temperatures. Therefore, this proposal will develop and characterize fibre reinforced cement based foams to achieve a high performance ultra-lightweight building material and also advance the fundamental understanding of brittle cellular solids that are based on Portland cement systems.