Economic and life cycle assessment of recycling municipal glass as a pozzolan in portland cement concrete production

The environmental and economic qualities associated with processing recycled glass cullet recovered from a municipal solid waste (MSW) materials recovery facility (MRF) into glass powder (GP) to be used as a pozzolanic material in the production of portland cement concrete were assessed. Through an evaluation of life cycle impacts and system costs, the feasibility of a potential pozzolan market was evaluated in comparison to the two most common management strategies for recycled glass cullet: (1) traditional recycling into new glass containers, and (2) disposal to a landfill (including potential use as landfill depression fill material). The investment of a MRF in a GP processing system became feasible if at least 50,000 metric tonnes (tonnes) of cullet were processed annually (based on a 10-year lifespan and 4500 h per year plant operating time). At this annual throughput capacity, a MRF could achieve a processing cost capable of producing GP at a cost competitive with the current retail value of Class F coal fly ash, another known pozzolan. GP processing costs decreased as annual cullet throughput increased. The feasibility of such a GP pozzolan market was further analyzed through an applied case study of MRF cullet availability in North Central Florida, USA.