Effect of Admixed Recycled Aggregate Concrete on Properties of Fresh and Hardened Concrete

Recycled aggregate (RA) obtained from crushed concrete rubble, instead of being stored, can be reused in building industry. An attempt has been made to study the possibility of reusing the recycled concrete aggregate from demolished structures in the place of fresh aggregate. Four series of mixes of control concrete with fresh aggregate and recycled concrete aggregate with three different ages of 5,10, and 15 years were prepared for the present study and used with three different combinations, 0% fly ash, 20% fly ash, and 20% fly ash with super plasticizer. The basic properties of aggregates, such as water absorption and specific gravity, mechanical properties, such as abrasion resistance, effect, and crushing values were considered. Workability of fresh concrete and strength parameters of hardened concrete, such as compressive strength and tensile strength, were studied. The preceding properties were tested for three different periods of curing of 7, 14, and 28 days. All these mixes were designed for M25 grade of concrete. In the present work, a comparison was made between the results of a laboratory investigation on various physical properties of concrete made with recycled aggregate concrete with fresh aggregate concrete and found that the results are encouraging to use concrete with RA. DOI: 10.10611(ASCE)MT.1943-5533.0000393. (C) 2012 American Society of Civil Engineers.