Economic comparison of recycling over-ordered fresh concrete: A case study approach

Recycling of construction material helps save the limited landfill space. Among various types of materials, concrete waste accounts of about 50% of the total waste generation. Current off-site practices for ready mixed concrete batching plant generate a significant quantity of fresh concrete waste through over-order from construction sites. The use of concrete reclaimer is one of the methods to reclaim these concrete wastes, which separates coarse aggregate, sand and cement from fresh concrete. Although there are some concrete producers in Hong Kong providing concrete reclaimers in their plants, they are only used to flush and dilute the cement slurry from the concrete, which will still be ultimately send all to dumping areas. The reluctance of most concrete producers in reclaiming aggregate from the concrete waste is due to its high cost of treatment and lack of space around the plant. Therefore, this paper puts forth a scheme of economical considerations in recycling over-ordered concrete by concrete reclaimer. A comparative study on costs and benefits between the current practices and the proposed recycling plan is examined. The study shows that the costs of the current practices in dumping over-ordered fresh concrete waste to landfill areas are double that of the proposed aggregate recycling plan. Therefore, the adoption of concrete reclaimer in recycling the over-ordered fresh concrete can provide a cost-effective method for the construction industry and help saving the environment.