Development of innovative lightweight shock absorbing cement based composites

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Impact loading is a common occurrence in fast moving traffic, pile driving and aircraft landing. It is specifically associated with gas explosion, earthquakes, and blast events. During such dynamic loads, the built environment intended to withstand these events witnesses a large amount of energy suddenly imparted to the structure. Therefore, protective systems and crash cushions require materials which not merely survive the impact but in fact trap the projectile and absorb the shock. Such materials are essential in applications, both civil (traffic barriers, firing ranges, runways) and military, such as in protective construction by the Canadian Provincial Reconstruction Team in Afghanistan. The inherent softness of composites based on lightweight aggregates and cementitious foams makes them an ideal candidate for shock absorbing systems, provided their response to such severe loading is properly understood. In fact, they make for an environment-friendly alternative with excellent potential for the re-use of industrial waste products as supplementary cementing admixtures (calcined oil-sands tailings from Northern Alberta) and lightweight aggregates (bottom ash from coal fed thermal plants in the vicinity of Edmonton, AB). Unfortunately, we do not fully understand how lightweight cement-based materials respond under impact loading. No predictive models exist and this hinders design and utilization of this decidedly promising class of construction materials. Therefore, there is a tremendous need to characterize the effect of density on the fracture mechanics of cement-based materials at high loading rates. This proposal will optimize and model fiber-reinforced lightweight cementitious composites under impact. Based on this, it will develop shock absorbing cement-based composites for a variety of civil and military applications. In addition, it will explore the possible re-use of industrial waste in the vicinity of Edmonton, AB.