The impact of aggregates from recycling, discharge time and mixing technique on the consistency of concrete

摘要

Concretes prepared by the application of the triple mixing approach and by the use of both recycled concrete aggregate(RCA)and recycled clay brick aggregate(RBA)were tested in terms of loss of consistency.Fly ash was used to improve the performance of recycled aggregates during mixing-this is a specific aspect of the triple-mixing method.The slump test was performed immediately after mixing, as well as after next 90 minutes.The results were evaluated from the point of view of prolonged discharge time.Concrete consistency changes with time, having the impact on technological processes at construction site.Over the discharge time, the RBA-based concrete achieved the worst result-by 87% slump loss.Discharge time influenced the slump loss more favourably in the case of normal mixing and in the case of using natural aggregate(NA).The substitution of NA with both the RCA and RBA caused the slump loss turned worse, while RCA provided better results than RBA.However, the substitution of NA with both RCA and RBA resulted in more favourable change in the slump loss when concrete was mixed by 3M method.