Decreasing natural resources of coarse & fine aggregates and growing issues with trash management assistance the beneficiation of trash materials. The quality and uniformity of the recycled aggregate and the concrete generated from it are clearly influenced by the degree of processing and the original concrete's quality, according to research on recycled aggregate concrete. Adhered mortar on the demolished aggregate is the major factor which influences the reuse of recycled aggregate. Different methods are given in the literature to remove the adhered mortar such as mechanical grinding, thermal treatment, chemical treatment etc.
In the present study, the demolished waste after testing was taken from the waste concrete present in Structure Engineering Laboratory in B.I.E.T., Jhansi. With a 5 kg hammer, pulverized concrete was broken into coarse aggregates that were 20 mm and smaller. This coarse aggregate derived from the demolished waste, was put in the Los Angles abrasion apparatus for3, 5& 8 min duration. It was observed that after 3 minutes, mortar removal was marginal and after 8 min, abrasion causes loss & rough edges of surface to smooth edges. The optimal mortar removal and maintenance of rough edges was observed after 5 minutes abrasion. Now coarse aggregates obtained after mechanical grinding were immersed in the various concentration of lime of 1N, 1.5N, 2N, 2.5N and 3N for different period of time of 3 days and 7 days. Lime treated aggregate was sieved through 10mm and 20mm sieves and washed with clean water and oven dried subsequently for use in concrete mix design. The natural and recycled coarse aggregates were proportioned by replacing natural coarse aggregates at intervals of 10% by weight with recycled coarse aggregates in the M40 grade concrete. These concrete cubes were tested after 7 and 28 days for cube compressive strength.
In this study, It is discovered that RCA concrete has More water is absorbed, the specific gravity is lower, and the bulk density is lower than natural concrete. This results from the existence of adhered mortar on RCA. It is also found that a rise in the % of recycled coarse aggregate decrease the compressive strength of the mix. So RCA is up to 10% can be effectively used to get the compressive strength in order to achieve target strength of the desired design mix.