Abstract:
The objective of this research was to study instantaneous and long - term deflection of reinforced c oncrete beams
adding steel fibers and using recycled concrete course aggregate under sustained load. Recycled concrete aggregates
were obtained by crashing harden concrete having the compressive strength of 200+10% ksc and 400+10%
ksc and then selecting the aggregate from the retained parts on the standard sieve No.4, 3/8 and 1/2 in. The size
of reinforced concrete beam used in the tests was 10x10x150 cm, and the beams were reinforced with a steel round
bar with 9 mm in diameter. The beams were cured by immersing into water for 28 days. Parameters investigated were
two levels of volume fraction of steel fibers (0.3% and 0.5%), two levels of sustained load (40% and 60% of ultimate
load capacity), and compressive strength of recycle aggregate. The beam tests were divided into 2 parts. The first part
focused on the flexural tests to determine the relationship between an applied moment and midspan deflection. The
second part dealt with the tests to determine the relationship between the deflection at midspan and elapsed time of
sustained loading. The results from the study revealed that the use of recycled concrete aggregate and steel fibers would
affect on both instantaneous and long-term deflection of reinforced concrete beams.