DEVELOPMENT OF METHOD AND CRITERIA FOR EVALUATION OF DRY-WASHING EFFICIENCY WITH RE-CON ZERO EVO

Abstract

Society recognises the need for the preservation of nature and the need for better resource utilisation. Integration of good practice in the building industry is mainly targeted at reducing or completely eliminating waste. One of the waste sources in the concrete industry is created in washing facilities and consists of returned concrete, washing water and cement slurry. Concrete trucks are washed with a large amount of water, and the most common treatment of washing water is sedimentation in several interconnected sedimentation pools. Recycled water from the cleaning facility is commonly used again for cleaning or disposed into nature. The sedimented slurry is collected several times a year and disposed at a landfill. Re-Con Zero EVO (RCZ) is a product introduced by Mapei to transform fresh returned concrete into a dry, granular material. Re-Con dry-washing is a subsequent process that was developed to reduce waste, cement slurry, in concrete trucks by using the dry granular material from the RCZ process as an absorbing material for the slurry in the trucks. Its efficiency and benefits are the main subjects of this study. <p> <p>Parameters for dry-washing efficiency evaluation are based on the amount of fine particles left in the truck after Re-Con dry-washing and properties of the Re-Con dry-washing aggregates (Re-Con DWA), especially particle size distribution and water absorption. Two different approaches were developed, and results were compared. The first approach focused on cleaning cement slurry exclusively, and the second approach assumes that there is still concrete in the concrete truck before cleaning. Dry-washing of a slurry was performed with 10, 15 and 20 kg of Re-Con DWA and testing showed the best washing effect at the highest dosage of 20 kg of Re-Con DWA. The second test setup determined the amount of ReCon DWA differently for washing of concrete, and obtained better particle size distribution with lower content of grains over 22.4 mm. The efficiency of dry-washing with Recon Zero EVO was around 70% in both test setups and showed promising results, which needs further investigations.