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被用作非结构填料和地热保温材料，特别是由于其低密度和易流动而被使用。然而，这类可控低强度和超轻质水泥基复合材料还没有很好地表征，特别是在加拿大北部极端寒冷的应用中。此外，高水泥含量和高孔隙率的结合导致了广泛的耐久性问题，包括收缩开裂、早期热生成和抗硫酸盐侵蚀能力差。此外，随着硅酸盐水泥的水化，内部细胞结构的演变导致了固有的时间依赖性热性能。除了目前在加拿大进行的非结构应用外，水泥基泡沫在碰撞缓冲垫和地震中抗液化方面也存在巨大的潜力。然而，由于缺乏最基本的高应变率特性，它在减震中的应用受到阻碍，这与其他脆性细胞固体的数据库不同。为了利用其优越的流变性、细胞结构和耐热性的优势，水泥基泡沫必须i)增韧和ii)变得耐用，同时对其在可变加载率和温度下的机械、流变、热学和运输性能进行量化。因此，本提案将开发和表征纤维增强水泥泡沫，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细胞固体的基本理解。

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.