Experimental Study of Recycled Concrete Columns under Large Eccentric Compression

Through experimental tests of 9 groups of recycled concrete specimens under large eccentric compression, issues were discussed concerning the effects of recycled aggregate displacement ratio on recycled concrete column's ultimate load, damage stage, and mid-span deflection under the same eccentricity. It was concluded from the experiment that the ultimate load of recycled concrete column decreased gradually as recycled aggregate's percentage rose from 0 to 80%. However when this percentage maintained 50%, the ultimate load mentioned above increased. Conclusions could also be drawn from the test that recycled concrete large eccentric compression column possessed obvious elastic stage, crack stage and fracturation stage, satisfying plane cross-section assumption in the process of buckling. Its mid-span deflection increased with the increment of recycled aggregate displacement ratio. Tensile area reinforcement basically varied linearly. When load reached 100kN and 200kN, the concrete cracked and the strain of tensile reinforcement increased suddenly. The larger the recycled aggregate displacement ratio, the larger the increment of reinforcement strain, deriving thus the conclusion that the ductility of recycled concrete column was a little bit higher than that of ordinary concrete column, and that the strain of compressive area reinforcement changed linearly before the exertion of ultimate load, and yielded with the exertion of ultimate load. The maximum strain of compressive area reinforcement conformed to that of ordinary concrete column. It was suggested the application of concrete structures with 50% recycled aggregate in engineering.