SBIR Phase II: Controlled Foam Injection for the Fracturing of Rock and Concrete

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This Small Business Innovation Research Phase II project is directed towards the study and refinement of anew non-explosive rock excavation and concrete demolition method. The method involves injecting high-pressure foam into pre-drilled holes in the rock or concrete to be broken through a barrel incorporating a new hole bottom sealing method. The high viscosity of the foam (as compared to a gas) combined with its stored energy characteristics (as compared to a liquid) result in very controlled breakage. The Phase I program demonstrated that the method can consistently break rock or concrete at pressures an order of magnitude less than in explosive or propellant based methods. Airblast and flyrock are reduced to very benign levels allowing the method to be applied in a continuous manner and to be used in urban and other sensitive environments. The incremental breakage of the method combined with the simplicity of the requisite hardware make the method highly amenable to automation. The Phase II project will investigate foam formulations to further improve the efficiency of the method, improved hole sealing methods, automation of the drill and break cycle, and integration of the technology with other mining and tunneling operations, such as mucking and ground control. The controlled foam injection method for rock breakage could have many applications in infrastructure development and maintenance. The method would be ideal for developing utility tunnels under existing streets and buildings, providing access tunnels or shafts to existing subway systems, modifying the round bores produced by tunnel boring machines or excavating underground space for buildings. In the area of concrete breakage and stripping the method would be useful for demolishing concrete structures when explosive methods were precluded or where salvage and recycling of building or structure components are desirable.