Environmental Benefits of Green Concrete

Of the approximately 11 million tonnes of annual solid concrete and demolition waste (C&D) in Canada, concrete accounts for about 52% by weight. However, most of this concrete is used as highway base or sent to landfills for disposal; only a very small portion of the concrete waste is reused in building construction. Considering the fact that usable natural aggregate (NA) supplies are diminishing, there will be a high demand for recycled concrete aggregates (RCA) to be used in the so called ldquogreen concrete (GC)rdquo. Using recycled concrete as aggregate will help reduce the total cost of concrete production because aggregates need not be hauled from remote locations, but obtained locally. The combination of RCA with significant quantities of fly ash or slag as replacement for Portland cement is particularly attractive from both economic and environmental perspectives. GC will reduce the demand for natural resources, the associated energy consumption, and green house gas (GHG) emissions required to produce aggregates and cement. These reductions can be considered as one of the construction industry's major contributions to Canada's GHG emission reduction objective. Although there are some guidelines/specifications established by different countries such as the UK and Japan, currently, there are no established guidelines for producing GC in Canada. This paper presents the environmental and economic benefits of increasing the use of GC in the construction industry and highlights the objectives of an ongoing research by the authors on GC.