Effect of the constituents (asphalt, clay materials, floating particles and fines) of construction and demolition waste on the properties of recycled concretes

摘要

The present study explores the viability of reusing mixed recycled aggregate from construction anduddemolition waste as a partial (25 and 50 wt%) replacement for natural coarse aggregate in the manufactureudof concretes with a compressive strength of 30 MPa. It further analyses the effect of some of the constituentsud(asphalt, clay-based materials, floating particles and fines) of these recycled aggregates on theudproperties of recycled concretes. Despite the high asphalt and floating particle content of the recycledudaggregate used, came from waste management plant at Glasgow, it was found to have no adverse effectudon the workability of the new concretes. Hardened concrete density and compressive strength wereudobserved to decline with increasing replacement ratios, at a variable rate depending on the componentsudof the recycled aggregate mix and the thickness of their ITZs (the thicker the weaker). While concreteudwith 25% recycled aggregate exhibited lower sorptivity than the reference concrete, absorption wasudhigher when the replacement ratio was 50%. The findings showed that this type of recycled aggregateudcan be used in concrete manufactured for housing applications and confirmed the importance of goodudconstruction and demolition waste management to deliver high quality recycled aggregate.