The U.S. infrastructure is at great risk and in urgent need to be repaired and upgraded, but it is a great challenge to handle the significant amount of concrete waste to be generated by doing so. An ideal solution is complete recycling of the concrete waste and utilization of it in production of new concrete. Currently, however, the recycling of concrete waste in the U.S. is predominately limited to the use of concrete aggregates in low-specification applications such as base course and non-structural fill with the remainder still being landfilled. The few methods proposed for complete recycling of concrete waste require re-clinkering of the hydrated cement in the concrete waste using the standard high temperature cement kiln procedures and thus consume significant amount of energy and release large quantity of CO2. The major goal of this research is to investigate the feasibility of complete recycling of concrete waste using the innovative geopolymerization technology.

Specifically, the proposed research has the following objectives:

– Systematically study the macro-scale behavior of geopolymeric concrete from completely recycled concrete waste by conducting different mechanical tests.

– Investigate the micro/nano-scale structure and characteristics of geopolymeric concrete from completely recycled concrete waste at different conditions.

– Conduct simulations to explore how micro/nano-scale characteristics affect the macro-scale behavior of geopolymeric concrete from completely recycled concrete waste.

The geopolymerization method evaluated in this project can completely recycle concrete waste without using any ordinary Portland cement (OPC). Successful completion of the project will promote complete recycling of concrete waste in a sustainable way, saving the high monetary and environmental costs related to transportation and disposal of concrete waste, reducing the demand for virgin materials that would need quarrying, and decreasing the use of energy-intensive OPC.  Another potential impact is that concrete stockpiled in C&D landfills may be mined for re-constitution via the geopolymerization technique, thus creating a potential revenue source for C&D landfill owners.