Development and Characterization of High Performance Fibre Reinforced Cement Based Foams

密度在300-800 kg/m3之间的水泥基泡沫最常用作非结构性填料和地热绝缘，并且特别地由于其低密度和易于流动而被采用。然而，这类受控的低强度和超轻质水泥基复合材料还没有得到很好的表征，特别是在加拿大北部的极端寒冷地区的应用。此外，高水泥含量和高孔隙率的组合导致广泛的耐久性问题，包括收缩开裂、早期生热和抗硫酸盐侵蚀性差。此外，当波特兰水泥经历水合时，内部蜂窝结构的演变导致固有地依赖于时间的热性能。除了目前在加拿大正在进行的非结构性应用外，水泥基泡沫材料在防撞垫和地震期间抵抗液化方面存在巨大潜力。然而，它在减震中的应用受到阻碍，甚至缺乏最基本的高应变率表征，不像其他脆性多孔固体的数据库。为了利用其优异的上级流变性、多孔结构和耐热性的益处，水泥基泡沫必须i）增韧和ii）使其耐用，伴随着在可变加载速率和温度下其机械、流变、热和运输性能的量化。因此，本提案将开发和表征纤维增强水泥基泡沫，以实现高性能超轻质建筑材料，并推进对基于波特兰水泥系统的脆性多孔固体的基本理解。

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.