Specific properties of recycled aggregate concrete production technology

Abstract

This state-of-the-art paper deals with the differences in production technology of concrete made with recycled aggregate. The properties of recycled aggregate, as a component for new concrete production, are being analyzed in the first part of the paper as well as its specifics and distinctions in comparison to natural aggregate. Two-stage-mixing approaches, as a way to achieve concrete performance improvement, are also described and the examples of recycled aggregate concrete mixing with the addition of silica fume are given. The influence of variation of concrete component materials dosage is also analyzed. Further more, the examples of mortar component removal from recycled aggregate are described (e.g. with the aid of different acids) with the influence of this process on physical and mechanical properties of new concrete. Also, different ways of preparation of recycled aggregate (air-dried, water-saturated, surface-dry and oven-dried) are discussed. At the end, general guidelines for recycled aggregate concrete mix design are given.

Ovaj pregledni rad govori o specifičnostima tehnologije spravljanja betona na bazi recikliranog agregata. U prvom delu rada analiziraju se svojstva recikliranog agregata kao komponente za spravljanje novog betona, njegove specifičnosti i razlike u odnosu na prirodni agregat. Daju se opisi mešanja iz dve faze koje se primenjuje u cilju poboljšanja performansi novog betona, kao i primeri spravljanja betona na bazi recikliranog agregata sa dodatkom silikatne prašine. Analiziran je i uticaj promene redosleda doziranja sastavnih komponenata betona. Dalje, prikazani su primeri u kojima se opisuju načini uklanjanja malterske komponente sa recikliranog agregata, npr. pomoću različitih kiselina, sa uticajem na fizička i mehanička svojstva novodobijenih betona, a takođe i različiti načini pripreme recikliranog agregata (sušen na vazduhu, sušen u sušnici i vodomzasićen+površinski suv). Na kraju, prikazuju se generalne smernice za proces projektovanja sastava betona na bazi recikliranog agregata.