Enhancing Returned Fresh Concrete Reusability Through Digital Monitoring
摘要
Reducing waste in concrete production is crucial for lowering carbon emissions. In the UK, in-situ concrete accounts for about 5% of generated waste, while globally, over 125 million tonnes of fresh concrete is returned to ready-mix plants annually. Conventional disposal and recycling methods pose cost and environmental challenges, making blending returned concrete into new batches a promising circular solution. This case study assesses the feasibility of blending returned fresh concrete at an industrial batch plant, analyzing its impact on key parameters and the role of digital monitoring in deployment. Cement hydration, influenced by ambient conditions and mix composition, determines the workable timeframe for blending. Temperature and maturity-based age tracking are essential in evaluating blending feasibility, especially when incorporating up to 50% returned concrete. Results show that blending up to 25% (≤2 m3 into 8 m3) does not affect compressive strength, eliminating the need for mix adjustments. However, higher blending rates (up to 50%), as per ASTM C1798, require close monitoring due to increased water demand and loss of consistence. Digital truck monitoring, providing real-time data on temperature, batch age, consistence, and volume, ensures blended concrete meets performance standards. Calibration charts and digital monitoring help determine viable time-temperature combinations for successful blending. This approach offers a sustainable, resource-efficient solution to fresh concrete waste, promoting circularity in concrete production.