Sustained Service Load Behavior of Concrete Beams with Recycled Concrete Aggregates

8 This paper describes an experimental investigation on the time-dependent sustained 9 service-load behavior of normal strength concrete beams with recycled concrete aggregates 10 (RCA) used as replacement for coarse natural aggregates (NA). Eighteen beams were tested 11 incorporating different aggregate replacement amounts, reinforcing details, concrete age at 12 superimposed loading, and beams with and without cracking upon immediate load application. It 13 is shown that increased amounts of RCA result in significant increases in both the immediate and 14 long-term deflections of concrete beams, but this effect is smaller for beams with increased 15 cracking. Greater creep and shrinkage deformations also cause a greater downward shifting of 16 the neutral axis (i.e., increase of the neutral axis depth) in RCA concrete beams as compared to 17 NA concrete beams. ACI 318 and Eurocode generally gave good design estimates for the 18 immediate deflections of the test specimens. In comparison, the long-term deflections were 19 significantly underestimated for the uncracked beams. For the cracked beams, the long-term 20 deflections were somewhat underestimated by ACI 318 and overestimated by Eurocode by 21 approximately similar percent errors. The ability of the design methods to predict the measured 22 deflections did not differ significantly between the NA concrete and RCA concrete beams. 23