Analysis of CO₂ emissions and waste elimination capacity of different recycling strategies applied in ready-mixed concrete plants

Análise das emissões de CO₂ e capacidade de eliminação de resíduos de diferentes estratégias de reciclagem aplicadas em centrais dosadoras de concreto

abstract:

The volume of waste generated by ready-mix concrete (RMC) plants in Brazil is significant. According to Oliveira et al. [1] waste from construction and demolition in Brazil was approximately 45-79 million tons and most of those waste is sent to landfills (79%). This study presents an assessment of the RMC plant waste reduction capacity using 3 different methods: (a) reuse of concrete in the fresh state by using hydration-stabilizing admixtures (HSA); (b) recycling of concrete aggregates by separating the aggregates from the cement paste before the concrete hardens; (c) recycling of hardened concrete as aggregates through the crushing process. Results indicated that concretes with compressive strengths up to 25.0 MPa are more effective in reducing CO₂ emission and consequently CO₂ footprint when using method (b); if evaluating higher resistance classes, method (a) was the most effective.

Keywords:
ready mix concrete waste; CO₂ footprint; field test; recycled aggregate; hydration stabilizing admixtures