Abstract: A study based upon the analysis of the various experimental results for the fresh and hardened stage of the different concrete mix with different replacement levels of natural coarse aggregate with recycle coarse aggregates is presented in the paper. The recycled coarse aggregate were obtained from mobile crusher plant located in Sangrur (Punjab). The crushed aggregate was that of M30 grade demolished bridge deck slab and pier.Three types of concrete mixture were selected for a testing, i.e. M25, M30 &M35grade. The first two mixtures i.e(M25 &M30)are somewhat same as that of parent concrete (M30) from which recycled coarse aggregate is derived, so they were selected as 1st series where as 3rd mixture M35 was selected as 2nd series. For the first series, concrete was made entirely with natural aggregate as a control specimen and concrete was made with recycle coarse aggregate with 50&100% replacement levels of natural coarse aggregate. For 2nd series, concrete was made entirely with natural coarse aggregate as control specimen and two types of concrete with fly ash (15% and 25% replacement of cement) and recycle coarse aggregate (50% and 100%replacement of natural coarse aggregate) were made. 72 cube specimen and 36 beam specimens were made for testing of basic properties (cubes for compressive strength and split tensile strength; beam specimen for flexural strength) of hardened concrete. The fresh property i.e, the slump value for each investigated concrete type is also presented in the paper. In 1st series (M25 &M30), recycled aggregate concrete did not diverge its properties as compared with the control specimen, regardless of the replacement ratio by recycled aggregates. However for the 2nd series (M35), in order to achieve the desired strength, fly ash was used as the replacement of cement. The test results obtained were somewhat more than that of control sample.
Keywords: recycle coarse aggregate, natural coarse aggregate, fly ash, structural concrete.