Influence of recycled aggregates on mechanical properties of HS/HPC

Recently, aggregates derived from demolished concrete structures were of relatively low strength, and applications were of secondary importance. Since a short time, the necessity of demolition of structures with strong concrete, like building frames or bridge beams, has appeared and created the source of recycled aggregate of quite new generation, Besides of obvious environmental aims recycling of concrete has gained new economical aspects. Concrete in responsible structures, with strength of 40-70 MPa for instance, was originally mixed from aggregate of good quality, e.g. granite or basalt, and with large amount of cement. The aggregate obtained from crushing of such structures retained some binding abilities as may be activated by means of silica fume or fly ash admixtures. Generally, such aggregates are different from natural and, consequently, concrete made with use of them has specific properties. The results of research on mechanical properties of structural recycled high performance concrete (RHPC) are presented. (C) 2002 Elsevier Science Ltd. All rights reserved.